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SKULL BASE 360°
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SKULL BASE 360°-Part 1
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SKULL BASE 360°-Part 2
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[ Dated: 26-10-14 ]
I will update continuosly with date tag at the end as I am getting more
& more information
Great teachers – All this is their work .
I am just the reader of their books .
Prof. Paolo castelnuovo
Prof. Aldo Stamm Prof. Mario Sanna
Prof. Magnan
For Other powerpoint presentatioins
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“ Skull base 360° ”
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getting more & more information
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Below presentation is
SKULL BASE 360°-Part 1
Indetail eloborate description for
each part of skullbase360 done at
www.skullbase360.in
» Presentation by
» Dr. N. Murali Chand DLO MS (ENT) FHM
» Fellowship in HIV medicine, MAMC, New Delhi
» My website = www.integratedmedicine.co.in
• www.skullbase360.in
» Cell= +91 99496 77605
Skull base 360°- part 1
Skull base 360°- part 1
Skull base 360°- part 1
Approach
1. External corridor doesn’t matter except cosmesis , only
internal corridor matters – so in Open approaches of skull
base also use endoscope to get best results – see this video
how the Dr. Dugani Suresh ; Neurosurgeon is using
endoscope in Weber Fergusson incision
https://www.youtube.com/watch?v=Y95Jf3u8S8o&feature=y
outu.be
2. Most of the times “Don’t cross the NERVES”
Prof. Amin Kassam
CORRIDOR SURGERY
• Video 1
https://www.youtube.com/watch?v=J6ji53nKQy
0
Video 2
https://www.youtube.com/watch?v=56Wt4vQ9
KgE
External carotid artery ligation – Note at division of common carotid , external
carotid artery is medial to internal carotid artery – Sometimes the division
may go up very high in neck .
Only to lesion lateral to meridian
of pupil in frontal sinus we have
to do osteoplastic flap
The landmarks for canine fossa
puncture/trephine are the
intersection between a vertical line
through the pupil and a horizontal line
drawn through the floor of the nose.
Enhanced T1-weighted magnetic resonance imaging (MRI),
coronal section demonstrates a right nasoethmoidal lesion (adenocarcinoma)
with an “hourglass” intradural extension through the ethmoidal
roof. Diffuse enhancement of the dural layer (arrowheads) over
the orbital roof is suspicious for neoplastic spread. The vertical lines limit
the area of the dura safely resectable by a pure endoscopic approach.
“Up & below” approach to frontal
sinus
Illustration of the septal incisions necessary to achieve good access to the entire
anterior wall of the maxillary sinus for
tumors either originating from this region or with a significant anterior wall
attachment. (B) Cadaveric image demonstrating the access to
the anterior wall (AW) of the maxillary sinus with a 70-degree diamond drill (D).
Skull base 360°- part 1
(A) The microdebrider blade has been passed through an inferior meatal antrostomy. Note the anterior fulcrum (nasal
vestibule, broken white arrow) and the posterior fulcrum (inferior meatal antrostomy, white arrow). The region of the maxillary
sinus
that can be cleared through this access is shaded. This shaded region is smaller with a middle meatal antrostomy. The single
fulcrum of
the canine fossa puncture is indicated (white arrow) (B,C,D), illustrating how the entire maxillary sinus can be accessed as the
blade
only has a single fulcrum.Medial , posterior & Lateral walls approached through Caldwel-luc
The red arrows demonstrate
the endonasal approach, and the green arrows represents the transmaxillary
approach. The blue rectangle shows the parasellar structures.
A more perpendicular angle of attack is achieved in the transmaxillary
approach, and the distance to the target from this route is equal to or
smaller than that in the endonasal approach. Temp.: temporal.
Note that in the transmaxillary approach the
structures in the lateral wall of the sphenoid sinus are seen in a
more
perpendicular way, facilitating dissection of this region.
Close-up view of the cavernous sinus through the
transmaxillary
approach. Gasser.: gasserian.
The pink and orange lines
demonstrate the possible angles of maneuver in transmaxillary
approach.
In green is emphasized the possibilities of resection through
transmaxillary approach.
General view of the radial endoscopic accesses to the skull
base --- The green arrows represent the endonasal approaches,
the red arrows represent the transmaxillary
approaches, and the purple arrows represent the
subtemporal approaches. Note the multiple possibilities
of combination of these approaches.
Modified denkers approach - Blue dotted line shows
the medial maxillary wall. (B) Panoramic view after removing the medial
maxillary wall. Yellow dotted line shows the connected nasal cavity with maxillary sinus
the maxillary sinus.
Schematic demonstrating how the removal of the lateral
aspect of the piriform overture (in the red circle) enables a wider approach
(the green cone compared with the yellow cone) to the lateral
regions (pterygopalatine and infratemporal fossa).
Use combination of approaches when ever it is necessary -
Combined Transmastoid Middle Cranial
Fossa Approach
Rt lower cranial nerve shwannoma, which approach will be
better ,which approach will be better considering this side is
dominant sinus.
Answer
• Amit Keshri says - eight nerve was normal,so was 7th,removed tumor
completely with retrolab approach and to get space,the sigmoid plate was
decompressed and sinus retracted posteriorly after RMSO [ Retro mastoid
sub-occipital ] craniotomy without opening dura posteriorioly.
• Murali Chand Nallamothu For lower cranial nerve schawnnoma POTS
approach is the best - but here you are saying it is dominent sinus , no
need to sacrifice sigmoid sinus -- so in this case we can use extended
translabyrinthine approach for the AFB area part & at carotid canal area
part of the tumor can be removed by externally which is included in the
lower C - shaped incision
• Murali Chand Nallamothu if the 8 th nerve is good we can try
retrolabyrinthinne & retrosigmoid approach & take the help of endoscope.
• Post-op :
Posterior wall of maxillary sinus
Periosteum after removal of
posterior bony wall of maxillary
sinus – this periosteum must be
removed in JNA
MPP/VN
LPP/V2
Anteriorly MPP & LPP are fused & posterioly only they are divided .
Anteriorly MPP & LPP are fused & posterioly only they are divided .
Skull base 360°- part 1
Erosion of right greater wing of
sphenoid in a case of maxillary
carcinoma
Skull base 360°- part 1
Medial pterygoid is in line with lateral wall of Sphenoid
-- The superior vertical limb represents the paraclival ascending carotid and the
descending vertical limb is represents the medial pterygoid plate. The horizontal bar of
the ‘H’ is represented by the sphenoid sinus floor.
Lateral part of Posterior choanae is MPP
ET is just posterior to MPP
Lateral part of Posterior choanae is MPP
Medial pterygoid is in line with
Paraclival carotid
Tracking of infraorbital nerve leads to V2 & tracking of V2 leads to Trigeminal ganglion/ Middle
cranial fossa [ one of the best way to track middle crannial fossa is to track V 2 ]
Zygomatic nerve [ ZN ]
Infraorbital groove near inferior orbital fissure – If we drill supero-lateral to
infraorbital nerve it is nothing but Inferior orbital fissure .
Infraorbital groove near inferior orbital fissure – If we drill
supero-lateral to infraorbital nerve it is nothing but Inferior
orbital fissure .
Red ring = V2
Inferior orbital foramen continues as pterygomaxillary fissure .
Skull base 360°- part 1
One line along Vidian nerve & another
line along V2
Skull base 360°- part 1
Skull base 360°- part 1
Lateral to LPP & infra-orbital nerve [ or
V2 ] is Infratemporal fossa
One transverse line from Vidian nerve connecting
vertical line of V 2 & another transverse line from V2
The space above transverse line of Vidian nerve is Pterygoid Recess of
sphenoid – Read the CT – scan/ Plane the surgery by using these lines
The space above transverse line of V2 is
Middle cranial fossa ( Meckel’s cave ) –
Read the CT – scan/ Plane the surgery by
using these lines
Skull base 360°- part 1
Pterygo-palatine fossa
Skull base 360°- part 1
Pterygopalatine fossa. A, V2 (blue dotted line) coming out
from the foramen rotundum; B, green-yellow dotted line shows the
pterygopalatine ganglion; C, yellow dotted line shows the vidian
nerve; D, red dotted line shows the sphenopalatine artery; E, light blue
dotted line shows the great palatine nerve; F, white dotted line showing
the infraorbital artery.
EC – Ethmoidal crest – left nose
PVC , VC & FR are in 45 degree angle
line
Skull base 360°- part 1
Skull base 360°- part 1
Endoscopic view of PPG
Tracking of infraorbital nerve leads to V2 & tracking of V2 leads to Trigeminal ganglion/ Middle
cranial fossa [ one of the best way to track middle crannial fossa is to track V 2 ]
Zygomatic nerve [ ZN ]
Skull base 360°- part 1
Endoscopic view of foramen rotundum
area
Infratemporal fossa
Skull base 360°- part 1
Skull base 360°- part 1
Lateral pterygoid muscle devides
internal maxillary artery into 3 parts
1. The maxillary artery & Buccal nerve enters the infratemporal fossa between the
superior and inferior head of the
lateral pterygoid muscles.
2. Lingual nerve & Inferior alveolar nerve comes between medial pterygoid & lateral
pterygoid mucles .
.
Anteriorly lingual nerve & posteriorly Inferior Alveolar
nerve coming lateral to medial pterygoid muscle
Forceps behind IAN Forceps behind LN
IAN = Inferior alveolar nerve
Triangle formed by temporalis muscle ,
MPM & LPM
Mandibulotomy approach Endospic view
Post-maxillectomy “Fat pad” over temporalis muscle – which
is seen as Fat Pad [ FP ] in the triangle formed by temporalis
mucle , MTM & LPM endoscopically
Internal carotid artery going medial & posterior to
medial pterygoid muscle into Parapharyngeal space &
becoming Parapharyngeal carotid
Internal carotid artery going medial & posterior
to medial pterygoid muscle into Parapharyngeal
space & becoming Parapharyngeal carotid
After removing the LPM you will see Tensor veli palatini muscle (TVPM) coming
vertically downwards from anterior surface of ET , protecting parapharyngeal carotid
& after TVPM , thick Stylopharyngeal apneurosis (SPHA ) present ANTERIOR to
Parapharyngeal carotid [ So 2 structures ( TVPM & SPHA ) protecting parapharyngeal
carotid ]
After removing the LPM you will see Tensor veli palatini muscle (TVPM) coming
vertically downwards from anterior surface of ET , protecting parapharyngeal carotid
& after TVPM thick Stylopharyngeal apneurosis present ANTERIOR to Parapharyngeal
carotid -- Attached to this ET cartilage [ TP/ET attachment ] is the tensor palatini
(TP) fibrous aponeurosis (solid white line) with its muscle fibers seen below (broken
white line).
Hand model --
left hand = medial & lateral pterygoid
right hand = index is parapharyngeal
carotid , middle is IJV , ring is styloid &
stylopharyngeal muscles , thumb is
horizontal carotid
Skull base 360°- part 1
Parapharyngeal space
Skull base 360°- part 1
Skull base 360°- part 1
Skull base 360°- part 1
Skull base 360°- part 1
Skull base 360°- part 1
Skull base 360°- part 1
Skull base 360°- part 1
Skull base 360°- part 1
Skull base 360°- part 1
Internal carotid artery going medial & posterior to
medial pterygoid muscle into Parapharyngeal space &
becoming Parapharyngeal carotid
Post-styloid compartment = carotid space
Skull base 360°- part 1
Skull base 360°- part 1
Skull base 360°- part 1
Sphenoid osteum
Sphenoid osteum present at the juction of upper 2/3rd
& lower 1/3rd junction of Superior turbinate – this
became very useful to me in extensive fungal sinusitis
with polyposis & bleeding.
Three sequential indentations are made with the blunt end of the 4-mm
microdebrider blade starting at the medial upper limit of
the posterior bony choana and moving directly superiorly medial to the cut
edge of the superior turbinate.
L-OCR & M-OCR
L-OCR – Triangle
1. Upper boarder – Optic nerve & Opthalmic artery
2. Posterior boarder – Clinoidal carotid
3. Lower boarder – 3rd N. [ COM – Carotico-Occulomotor
membrane seperates 3rd N from Clinoidal carotid ]
[ 6th N. & 4th N. & V1 present inferior to 3rd N. ]
The optic strut has two neural-
facing surfaces( yellow dotted
lines) and one vascular-facing
surface (red dotted line).
[ COM – Carotico-Occulomotor
membrane seperates 3rd N from
Clinoidal carotid ]
Skull base 360°- part 1
The bone of the anterior clinoid (AC) process
has been left in place, positioned within the
lateral opticocarotid recess.
L-ocr is the space in Optic strut - not
the space in Anterior clinoid process
classification of the ophthalmic artery types
http://www.springerimages.com/Images/MedicineAndPublicHealth/1-
10.1007_s10143-006-0028-6-1
a = intradural type,
b = extradural supra-optic strut type [ Optic strut = L-OCR ]
c = extradural trans-optic strut type
on optic nerve, pr proximal ring, cdr carotid dural
ring= upper dural ring , ica internal carotid artery
I think this variation is type c
In both type a = intradural type,
b = extradural supra-optic strut types Opthalmic
foramen is in Optic canal
In Type c = extradural trans-optic strut type , the Opthalmic
foramen in Optic strut
L-ocr is the space in Optic strut - not the space
in Anterior clinoid process
Note Optic strut
Note Optic strut
- Right Optic nerve Anterio-superior view
Pneumatization of anterior clinoid process – in various planes + onodi cell on
both sides of sphenoid [ when transverse septum present in sphenoid it is
onodi cell ] + sphenoid recess on left side between V2 & VN .
The same cadaver photo what you are seeing in CT scan above – Note the supraoptic
pneumatisation [ present in anterior clinoid process ] in an onodi cell .
ICAcl clinoidal portion of the internal carotid artery , The clinoidal
segment of the internal carotid artery faces the posterior aspect of the optic
strut [L-OCR ]
Red ring – Pneumatization in Optic
strut – which is nothing but L-OCR
M-OCR
Sagittal sections and superior views of the sellar region showing the optic nerve and
chiasm, and carotid artery. The prefixed chiasm is located above the tuberculum. The
normal chiasm is located above the diaphragma. The postfixed chiasm is situated
above the dorsum.
1. M-OCR is nothing but Middle Clinoid Process [ indicated by
Green Button in both photos ]
2. M-OCR is the junction point of clinoidal carotid & Supra-
clinoidal carotid
The mOCR is located just medial tothe paraclinoidal-supraclinoidal ICA transition and inferior to
the distal cisternal segment of the ON(Labib et al. 2013 ).
Cl clivus, ICAc cavernous portion of the internal carotid artery, ON optic nerve, PG pituitary
gland, PS planum sphenoidale, TS tuberculum sellae, yellow asterisks upper dural ring, blue
arrowheads lower dural ring, white asterisk lateral optico-carotid recess, white circle medial
optico-carotid recess, white arrow ophthalmic artery, black arrows middle clinoid process, red
arrows lateral tubercular crest, yellow arrows endocranial region corresponding to MCP
1. The mOCR is placed at the confluence of the sella, tuberculum sellae, carotid
protuberance, optic canal and planum sphenoidale. The mOCR corresponds to the
lateral extent of the tuberculum sellae. ---- white asterisk lateral opticocarotid recess,
white circle medial opticocarotid recess ---
2. The mOCR is located just medial to the paraclinoidal-supraclinoidal ICA transition
and inferior to the distal cisternal segment of the ON (Labib et al. 2013 ).
Limits of the bone resection – Inner ring in below photo
• Posterior ethmoidal arteries
• Medial OCRs
SIS & IIS
Pituitary present between “ four blues”
SIS – superior intercavernous sinus &
IIS – inferior intercavernous sinus
1. Note ASIS & PSIS
2. Note Subarachnoid space at antero-superior area , which is the potential
CSF leak area in pituitary surgery .
Usually the DS originates some
millimeters below the TS.
PSIS – Posterior superior intercavernous sinus
ASIS & PSIS together called CIRCULAR SINUS
Cavernous Sinus
Skull base 360°- part 1
Right cavernous sinus dissection. The quadrilateral delimits the right cavernous sinus area.
a Before periosteal layer removal. b After periosteal layer removal. c Cavernous sinus
compartments.
L = Lateral; AI = antero- inferior; PS = posterosuperior compartment of the cavernous sinus (the
medial is a virtual space in continuity with the AI and PS).
CS divided into four virtual compartments:
1. medial,
2. lateral,
3. posterosuperior, and
4. anteroinferior
Medial and posterosuperior compartments are in strict continuity and do not contain nerves,
representing a surgical corridor without risk of neural damage. The anteroinferior and lateral
compartments contain the abducens nerve and, as surgical corridors, they are exposed to the
riskof injury to the VIth nerve.
Clivus
1. Upper Clivus
2. Middle Clivus
3. Lower Clivus
Basi occiput & basi sphenoid
Groove for medulla on Lower Clivus [ =
Basi Occiput ]
The 6 linear landmarks of the PCF superimposed on a midsagittal T1-weighted MR
imaging from a patient with CMI: herniation (HR), McRae line (MC), clivus (CL), Twining
line (TW), cerebellum (CR), and supraocciput (SO).
http://www.ajnr.org/content/34/9/1758.figures-
only?cited-by=yes&legid=ajnr;34/9/1758
1. Upper clivus – Upto 6th nerve entry dorello’s canal (petro-clival junction)
2. Middle clivus – from 6th nerve to jugular foramen
3. Lower clivus – from jugular foramen to foramen magnum
Pneumatization of the sphenoid sinus
The middle third (M. 1/3rd) begins at the sella
floor (SF) and extends to the floor of the sphenoid sinus (SSF), and the lower
third (L. 1/3rd) extends from the floor of the sphenoid
sinus to the foramen magnum (FM).
Pregnant of upper clivus is Sella
Infrapetrous Approach
Carotid-Clival window – Mid clivus
a. Petrosal face
b.Clival face
See the lower clivus relation to the
cochlea
In conchal sphenoid surgical landmarks –
1. posterior end of vomer or
keel of sphenoid tells about
the position of pituitary
2. lateral boarder of
posterior choana [ or MPP
]tells about paraclival carotid
& sellar carotid C-SHAPE
convex is lateral to this line
3. posterior lower boarder of
vomer is at the junction of
middle & lower 1/3rd clivus &
it is exactly at foramen
lacerum –my understanding
See the relationship between lower boarder of posterior end of vomer &
clivus – vomer lower boarder is at junction of mid & lower clivus – my
understanding
http://www.neurosurgicalapproaches.
com/2013/08/25/
Anterior cranial fossa dura Posterior cranial fossa dura
Very rare specimen..The vbj is far
inferior to floor of sphenoid sinus
The foramen lacerum (FL) is located lateral to the floor of the sphenoid sinus
at the level of the
spheno-petro-clival confuence.
JT jugular tubercle, HC hypoglossal canal –
addFig 3.78 also
Infrapetrous Approach
Carotid-Clival window – Mid clivus
a. Petrosal face
b.Clival face
When we are drilling lower clivus – lateral to
hypoglossal canal we get Jugular fossa
Inferior clival line (Fernandez-Miranda et al. 2012 )
The longus capitis and rectus capitis anterior muscle attach on the inferior surface of
the clivus. Below the RCAM the occipito-cervical joint capsule lies. The area of
attachement of the RCAM has been named inferior clival line (Fernandez-Miranda et
al. 2012 ) and correspond to the supracondylar groove (that is a landmark for the
hypoglossal canal).
Transcochlear approach
Note CL [ Lower clivus ] in these
photos after drilling of cochlea
Note CL [Lower clivus ] in these photos after drilling of cochlea
The clivus bone (CL) can be seen
medial to the internal carotid
artery (ICA). JB Jugular bulb
In the lower part of the approach, the
glossopharyngeal nerve
(IX) can be seen. V Trigeminal nerve, VIII Cochlear
nerve, AICA Anterior
inferior cerebellar artery, CL Clivus bone, DV
Dandy’s vein, FN Facial
nerve, FN(m) Mastoid segment of the facial nerve,
FN(t) Tympanic segment
of the facial nerve, GG Geniculate ganglion, ICA
Internal carotid
artery, JB Jugular bulb, MFD Middle fossa dura, SCA
Superior cerebellar
artery, SS Sigmoid sinus
Note CL [Lower clivus ] in these photos
after drilling of cochlea
BT- basal turn of the cochlea Fig. 8.34 The bone medial to the
internal carotid artery (ICA) has been
drilled and the clivus bone (CL) has
been reached. FN Facial nerve,
JB Jugular bulb
Note CL [Lower clivus ] in these photos
after drilling of cochlea
Note cochlear aqueduct [ CA ]
Here ICA is vertical part of carotid infront
to cochlea – this is not paraclival carotid
Note CL [ clivus ] in these photos after
drilling of cochlea
Note CL [Lower clivus ] in these photos
after drilling of cochlea
Note the contralateral vertebral
artery [ CVA ] in below photo
Lower clivus in Infratemporal fossa
approach
Skull base 360°- part 1
Skull base 360°- part 1
PVC – is occupied by Ascending
palatine artery (APA)
Craniopharyngioma removal -
Lilliquest membrane & Basillar artery
V3 & MMA
V 3 falls like niagara falls from middle cranial fossa to infratemporal
fossa 90 degrees away from V1 & V2 – it is anterior to all the 3
structures , Petrous carotid & ET tube & Parapharyngeal carotid
ATN = Auriculotemporal nerve
Skull base 360°- part 1
Skull base 360°- part 1
MMA
Skull base 360°- part 1
IAN = Inferior alveolar nerve
Skull base 360°- part 1
My forceps touched the lingual nerve , posterior to this LN is Inferior
alveolar nerve – These two nerves present in triangle formed by
medial pterygoid , lateral pterygoid & temporalis muscle
Skull base 360°- part 1
Chorda[CT] attached to LN
Chorda[CT] attached to LN
Schematic diagram for infratemporal
fossa approach
Sometimes V3 can be seen in the sphenoid sinus
– in “pneumosinus dilatans multiplex”
The greater wing of sphenoidal is almost completely pnematised.
So is the temporal bone on the left.the Left carotid can be traced
from the middle ear to the sphenoid - in “pneumosinus dilatans
multiplex”
V3 & MMA
V3 & MMA
V3[MN] & MMA & ET in lateral & Anterior skull base – see the
relationship of ET tube which is medial to V3 & MMA
Skull base 360°- part 1
Posterior boarder of Lateral pterygoid bone
leads to Foramen Ovale [ FO ] – Dr.Kuriakose
Posterior boarder of Lateral Pterygoid bone leads to Foramen
Ovale [ FO ] – Dr.Kuriakose
Endoscopically [ Anterior skull base ] if we follow upper end of LPT posteriorly we can
reach V3 [ Posterior boarder of Lateral Pterygoid bone leads to Foramen Ovale –
Dr.Kuriakose ]
In Infratemporal fossa approach- Posterior boarder of Lateral
pterygoid bone leads to Foramen Ovale [ FO ] – Dr.Kuriakose
V3 is anterior (infront) to Horizontal carotid (=
Petrous carotid ) & ET – It cause indentation on the
ET also .
In open approaches in maxillary swing approach as long
as you stay lateral to ET you will not injure the
horizontal part of carotid
Petrous carotid & paraclival carotid is
SADDLE shape – LEG of the rider is V3
V 3 is anteriror to all the 3 structures - Petrous carotid
& ET & Parapharyngeal carotid [ very imp ]
Cochlea in anterior skull base
b is cochlea in middle cranial
fossa – cochlear angle between
GSPN & IAC
V3 is an important landmark
to locate the post-styloid compartment, as it is anterior
to this space (Falcon et al. 2011 ) .
TP & LP
Skull base 360°- part 1
Skull base 360°- part 1
Skull base 360°- part 1
See the relationship of MPP & TP
which is just posterior
Skull base 360°- part 1
Skull base 360°- part 1
Sinus of Morgagni - In nasopharyngeal carcinoma, the tumor may
extend laterally and involve this sinus involving the Mandibular nerve. This produces a
triad of symptoms known as Trotter's triad [ 1) Conductive deafness ( due to
eustachian tube involvement) 2) Ipsilateral immobility of soft palate 3) Neuralgic pain
in the distribution of V3 ]
Skull base 360°- part 1
See the relationship between
LPP & V3 which is just posterior
Skull base 360°- part 1
Eustachian tube
ET is just posterior to MPP [ Lateral part of Posterior choanae is MPP ]
ET is just posterior to MPP
ET is pointing like an ARROW the posterior genu
of internal carotid [ ICAp & CF is parapharyngeal
carotid ]
Sinus of Morgagni - In nasopharyngeal carcinoma, the tumor may
extend laterally and involve this sinus involving the Mandibular nerve. This produces a
triad of symptoms known as Trotter's triad [ 1) Conductive deafness ( due to
eustachian tube involvement) 2) Ipsilateral immobility of soft palate 3) Neuralgic pain
in the distribution of V3 ]
Skull base 360°- part 1
Skull base 360°- part 1
black asterisks medial corridor to ICAp – TVPM attached to
anterior surface of ET – so if we go inbetween MPM & TVPM
we reach to ICAp
Skull base 360°- part 1
Bony-cartilagenous junction of ET tube is at posterior
genu of carotid - ET is pointing like an ARROW the
posterior genu of internal carotid
Yellow arrow - Bony-cartilagenous junction of ET tube is
at posterior genu of carotid - ET is pointing like an
ARROW the posterior genu of internal carotid
V 3 is anteriror to all the 3 structures - Petrous carotid
& ET & Parapharyngeal carotid [ very imp ]
Skull base 360°- part 1
ET tube in SPF [Spheno-petrosal fissure]
At bony-cartilagenous junction of ET tube – Horizonal
carotid & Parapharyngeal carotid is above & below ET -
My understanding
In open approaches in maxillary swing approach as long
as you stay lateral to ET you will not injure the
horizontal part of carotid
Fossa of Rossenmuller apex is laceral carotid [ Foramen Lacerum ]
pharyngeal recess (fossa of Rosenmüller), which projects laterally from the
posterolateral corner of the nasopharynx with its lateral apex facing the internal
carotid artery laterally and the foramen lacerum above;
endonasal approaches to expose the
area between the ICAs belong to the sagittal plane, and the
approaches
around the ICA define the coronal plane modules.
Note that the eustachian tube indicates the carotid canal only approximately. In other words, it lies on
a different CORONAL plane in respect of the vessel, and from an anterior viewpoint, it covers the vessel for all its
length. -- Medially the space between these two CORONAL planes is nothing but Fossa of Rosenmuller [ My understanding ]
Note that the eustachian tube indicates the carotid canal only approximately. In other
words, it lies on
a different CORONAL plane in respect of the vessel, and from an anterior viewpoint, it
covers the vessel for all its
length. -- Medially the space between these two CORONAL planes is nothing but
Fossa of Rosenmuller [ My understanding ]
Surgeons should have in mind that the external orifi ce of the carotid canal is not on
the same
coronal plane of the foramen lacerum (anterior genu). It is by far more posteriorly
located.
Skull base 360°- part 1
SOF [ Superior Orbital Fissure ]
Skull base 360°- part 1
Parts of SOF
1. Lateral part- LFT [ Liver functional tests ] Menumonic – Lacrimal N., Frontal
N.,Trochlear N.
2.Middle part
3. Medial/Inferior part
Parts of SOF
1. Lateral part- LFT [ Liver functional tests ] Menumonic – Lacrimal N., Frontal
N.,Trochlear N.
2.Middle part
3. Medial/Inferior part
Skull base 360°- part 1
Accessing intraconal lesions endonasally requires manipulation of the extraocular
muscles. The nerve branches that supply the oculomotor muscles run in the medial
surface of the muscles. Thus, try to avoid excessive retraction of the extraocular
muscles to avoid inadvertent muscle paresis.
SOF is the space between two Structs – Superiorly OS [
Optic Strut ] & Inferiorly MS [ Maxillary Strut ]
SOF is the space between two Structs – Superiorly OS [
Optic Strut ] & Inferiorly MS [ Maxillary Strut ]
SOF is the space between two Structs – Superiorly OS [
Optic Strut ] & Inferiorly MS [ Maxillary Strut ]
Anterior view of SOF Posterior view of SOF
Skull base 360°- part 1
Skull base 360°- part 1
Yellow line = “nasal” part of SOF
Clinically, the SOF and CS apex
represents a continuum.
endoscopic endonasal viewpoint the nasal window to
SOF is above V2, and below the lateral
optico-carotid recess.
blue-sky arrows SOF ; MS-Maxillary strut ;
MP-Maxillary prominence
Zonule of zinn - inserts on the infraoptic tubercle, which is often
found as a canal located beneath the optic strut .
The structure Infero-lateral to SOF is –
Horizontal part of carotid
Anterior to L-OCR is Superior Orbital
Fissure
SOF - Anterior
SOF - Posterior
MS- Maxillary strut /// Average
distance from the FR at PPF and the vertical segment of ICAc is
35 mm [ 3.5cm ] (Amin et al. 2010 ) .
SOF , Middle Fossa , V3 in line
vertically
GSPN-VIDIAN NERVE
GSPN passes above Horizontal [=petrous] carotid & passes
underneath V3 & crosses petro-paraclival carotid junction at
foramen lacerum before becoming vidian nerve
The bone overlying the internal auditory canal has been removed
and the dura of the canal has been removed near the fundus. The
facial nerve (FN) can be seen entering its labyrinthine segment to form the
geniculate ganglion (GG) more laterally. V Trigeminal nerve, < Acousticofacial
bundle, C Cochlea, ET Eustachian tube, GPN Greater petrosal
nerve, I Incus, IAC Internal auditory canal, ICA Internal carotid artery,
M Malleus, SSC Superior semicircular canal, SV Superior vestibular nerve
Observe the relationship between
GSPN & horizontal carotid
Fig. 2.62 The course of the horizontal segment of the internal carotid
artery (ICAh), as seen from the middle cranial fossa of a left temporal
bone. VI Abducent nerve, C Cochlea, GPN Greater petrosal nerve, IAC
Internal auditory canal, ICA(ic) Intracranial internal carotid, M Mandibular
nerve, MMA Middle meningeal artery, MX Maxillary nerve
Fig. 5.47 The view after completion of the middle crannial fossa approach. AE Arcuate eminence,
BB Bill’s bar, C Cochlea, FN(iac) Internal auditory canal segment
of the facial nerve, FN(t) Tympanic segment of the facial nerve,
G Geniculate ganglion, GPN Greater petrosal nerve, I Body of the incus,
L Labyrinthine segment of the facial nerve, M Head of the malleus,
MFD Middle fossa dura, SVN Superior vestibular nerve
In Infratemporal fossa - Note that the
greater petrosal nerve (GPN) is adherent
to the dura, and that retracting the dura
will lead to stress on the
facial nerve at the geniculate ganglion
(GG) level. Thus, if dural retraction
is needed, cutting the petrosal nerve will
prevent this injury.
In middle cranial fossa – same
point
Foramen lacerum
AFL = Anterior foramen
lacerum
* [ black asterisk ] = foramen
lacerum
Petrolingual area = foramen
lacerum
After elevating V3 anterior[infront] to ET & petrous carotid
observe -- GSPN continues as VN [ VN is lateral to paraclival
carotid ]
GSPN & GSPN groove in Surpra petrous window
ET eustachian tube, GPN greater petrosal nerve, MCFd dura of the middle cranial fossa, MMA
middle meningeal artery, SPS superior petrosal surface, TI trigeminal impression, V3 third
branch of the trigeminal nerve, yellow arrow accessory middle meningeal artery, white
asterisks greater petrosal nerve groove
Vidian nerve is formed by GSPN & Deep petrosal nerve – so GSPN (passes
underneath V3) crosses laterally the Horizontal carotid and paraclival carotid
junction (Prof.Kassam) & continues as Vidian nerve
Blue arrow – LPN &
Yellow arrow – GPN
Trans-pterygoid approch-- Vidian Artery present in 60% & enters at the junction of Horizontal
carotid & paraclival carotid – it is present above the Vidian nerve so while drilling vidian canal in
JNA first we have to drill inferior half and then upper half [the bone around the vidian
canal is drilled along its inferior half (from 3 o’clock to 9 o’clock) until the carotid
artery is identified at the lacerum segment ]
Vidian nerve - lateral to paraclival carotid &
medial to FO [ Foramen Ovale ]- actually it is
GSPN
Vidian canal & Spheno-palatine
foramen are in 90 degrees
Skull base 360°- part 1
Vidian nerve - lateral to paraclival
carotid
Vidian nerve - lateral to paraclival carotid
Vidian nerve - lateral to paraclival
carotid
Vidian nerve - lateral to paraclival carotid
Close vision of the middle cranial
fossa. The gasserian ganglion has been removed
Vidian nerve - lateral to paraclival
carotid
Axial T2-weighted magnetic resonance imaging (MRI) sequence
at the level of the vidian canal: 1, clivus; 2, pterygoid; 3,
horizontal tract
of the internal carotid artery (ICA); 4, vidian canal.
The space between V1 & V 2 and V2 & V3
is sphenoid sinus
Middle cranial fossa approach –
the nerve between V2 & V3 is VN
Anaterior skull base
Infratemporal fossa approach
type C
Middle cranial fossa approach –
the nerve between V2 & V3 is VN
Foramen lacerum
AFL = Anterior foramen
lacerum
* [ black asterisk ] = foramen
lacerum
Petrolingual area = foramen
lacerum
Vidian artery – origin from Laceral
segment
Lateral Recess is the space between V2
& Vidian nerve .
Courtesy – Dr. Satish Jain , Jaipur
Lateral Recess is the space between V2
& Vidian nerve .
Here TI [ trigeminal impression ] is V2
LRSS = Lateral recess of the
sphenoid sinus
Skull base 360°- part 1
Skull base 360°- part 1
Floor of Lateral recess is by ET ----
BS basisphenoid, ET eustachian tube, LRSS lateral recess of the sphenoid sinus, OPPB orbital
process of the palatine bone, PVA(s) palatovaginal artery(ies), RPm rhinopharyngeal mucosa,
SPAib inferior branch of the sphenopalatine artery, SPPB sphenoidal process of the palatine bone,
SS sphenoid sinus, RS rostrum sphenoidale, VN vidian nerve
Skull base 360°- part 1
Surpra petrous window
ET eustachian tube, GPN greater petrosal nerve, MCFd dura of the middle cranial fossa, MMA
middle meningeal artery, SPS superior petrosal surface, TI trigeminal impression, V3 third
branch of the trigeminal nerve, yellow arrow accessory middle meningeal artery, white
asterisks
greater petrosal nerve groove
Skull base 360°- part 1
Carotid nerve
Middle cranial fossa approach
The middle fossa retractor is fixed at the petrous
ridge (PR).
AE Arcuate eminence, GPN Greater petrosal
nerve, M Middle meningeal
artery
The expected location of the internal auditory canal
(IAC).
The bar-shaded areas are the locations for drilling. A
Anterior, AE Arcuate
eminence, GPN Greater petrosal nerve, MMA Middle
meningeal
artery, P Posterior
Petrous apex bone
Skull base 360°- part 1
Petrous apex - Quadrangular area
Petrous apex – Triangular area
Skull base 360°- part 1
Triangles
http://www.slideshare.net/INUB/endoscopic-anatomy-and-approaches-of-the-cavernous-sinus-
cadaver-study - Endoscopic view of the right cavernous sinus and neurovascular relations,
demonstrating the ‘S’ shaped configuration formed by the oculomotor, the abducens and the
vidian nerves. III oculomotor nerve, V1 ophthalmic nerve, V2 maxillary nerve, V3 mandibular nerve, VI
abducens nerve, C clivus, ICA-Sa anterior bend of the internal carotid artery–parasellar segment, ICA-Sp
posterior bend of the internal carotid artery–parasellar segment, ICA-C paraclival segment of the
internal carotid artery, ICA-L lacerum segment of the internal carotid artery, ICA-P petrous segment of
the internal carotid artery, PG pituitary gland, VC vidian canal, VN vidian nerve
6th nerve is parallel to V1 – in the
same direction of V1
6th nerve is parallel to V1 – in the same direction of V1
Skull base 360°- part 1
http://www.slideshare.net/INUB/endoscopic-anatomy-and-approaches-of-the-
cavernous-sinus-cadaver-study- Endoscopic view of the right cavernous sinus and its
neurovascular relations, demonstrating the triangular area formed by the medial
pterygoid process laterally, the parasellar ICA medially and the vidian nerve inferiorly
at the base. III oculomotor nerve, V1 ophthalmic nerve, V2 maxillary nerve, V3
mandibular nerve, VI abducens nerve, C clivus, ICA-Sa anterior bend of the internal
carotid artery–parasellar segment, ICA-Sp posterior bend of the internal carotid
artery–parasellar segment, ICA-C paraclival segment of the internal carotid artery, ICA-
L lacerum segment of the internal carotid artery, ICA-P petrous segment of the
internal carotid artery, PG pituitary gland, VC vidian canal, VN vidian nerve
1.Supra Trochanteric & Infratrochanteric Triangles
2. Upper & lower dural rings
http://www.slideshare.net/INUB/endoscopic-anatomy-and-approaches-of-the-cavernous-
sinus-cadaver-study -Endoscopic view of the right cavernous sinus showing its neurovascular
relations and the main anatomic areas. III oculomotor nerve, V1 ophthalmic nerve, V2
maxillary nerve, V3 mandibular nerve, VI abducens nerve, C clivus, ICA-Sa anterior bend of
the internal carotid artery–parasellar segment, ICA Sp posterior bend of the internal carotid
artery–parasellar segment, ICA-C paraclival segment of the internal carotid artery, ICA-L
lacerum segment of the internal carotid artery, ICA-P petrous segment of the internal carotid
artery, PG pituitary gland, VC vidian canal, VN vidian nerve, STA superior triangular area, SQA
superior quadrangular area, IQA inferior quadrangular area
1.Supra Trochanteric & Infratrochanteric Triangles
2. Upper & lower dural rings
http://www.slideshare.net/INUB/endoscopic-anatomy-and-approaches-of-the-
cavernous-sinus-cadaver-study - Endoscopic view (a), and a drawing (b) of the right
cavernous sinus demonstrating its neurovascular relations. c A drawing of the right
cavernous sinus demonstrating the exposure of the trochlear nerve after retracting
the oculomotor nerve. III oculomotor nerve, IV trochlear nerve, V1 ophthalmic nerve,
VI abducens nerve, ICA internal carotid artery, OA ophthalmic artery, OCh optic
chiasm, ON optic nerve, PG pituitary gland
Triangles of Middle cranial fossa – see Ant. Medial & Ant. Lateral triangles in both photos.
http://www.eneurosurgery.com/surgicaltrianglesofthecavernoussinus.html
Postero-medial Triangle = KAWASE triangle [Prof.KAWASE , JAPAN Neurosurgeon -below photo]
Fig. 22.31 Clinoidal and oculomotor triangles
have been opened and the anterior clinoid removed
up to the optic strut, exposing the carotido-
oculomotor membrane. The optic strut has two
neural-facing surfaces( yellow dotted lines) and one
vascular-facing surface (red dotted line). CN: cranial
nerve; Falc.: falciform; ICA: internal carotid artery;
Inf.:inferior; Lig.: ligament; Pet.: petrosal; V1: first
division; V2: second division; V3: third division of
trigeminal nerve.
ACP anterior clinoid process, APCF anterior
petroclinoid fold, DS dorsum sellae, ICF
interclinoid fold, PF pituitary fossa, PLL
petrolingual ligament (inferior sphenopetrosal
ligament), PPCF posterior petroclinoid fold, PS
planum sphenoidale, SSPL superior
sphenopetrosal ligament (Gruber’s ligament), TS
tuberculum sellae, black asterisk middle clinoid
process
Skull base 360°- part 1
Opticocarotid traiangle by Pterional
approach
Skull base 360°- part 1
CAROTID
KISSING CAROTIDS
1. http://radiopaedia.org/articles/kissing-carotids
2. http://www.ncbi.nlm.nih.gov/pubmed/17607445
• The term kissing carotids refers to
tortuous and elongated vessels which
touch in the midline. They can be be
found in:
• retropharynx 2
• intra-sphenoid 1
– within the pituitary fossa
– within sphenoid sinuses
– within sphenoid bones
• The significance of kissing carotids is
two-fold:
– may mimic intra-sellar pathology
– catastrophic if unknown or unreported
before transsphenoidal / retropharyngeal
surgery
Cervical kissing carotids – here also papaphayrngela kinking
present http://www.radrounds.com/photo/cervical-kissing-
carotids-1
Coronal MIP of aberrant medial course
of the carotids arteries showing the
internal carotids arteries nearly
touching at the C2 level.
An Aberrant Cervical Internal Carotid Artery in the Mouth
http://amjmed.org/an-aberrant-internal-carotid-artery-in-the-mouth/
Intrasellar kissing carotid arteries -This anomaly is particularly
important since it may cause or mimic pituitary disease and also may complicate transsphenoidal
surgery.http://www.scielo.br/scielo.php?script=sci_arttext&pid=S0004-
282X2007000200034&lng=en&nrm=iso&tlng=en
Skull base 360°- part 1
Looping / Kinking of
Parapharyngeal carotid
kinking or looping of the ICAp - when looping present para-pharyngeal carotid
comes to pre-styloid compartment – previously thought that para-pharyngeal
carotid never comes anterior to styloid mucles – which is UNTRUE
Skull base 360°- part 1
The stylopharyngeus and styloglossus
muscles are critical landmarks, being usually placed anterior to the great
vessels (Dallan et al. 2011 ).
Note that the presence of kinking or looping of the ICAp could make this
statement untrue.
Cervical kissing carotids – here also papaphayrngela kinking
present http://www.radrounds.com/photo/cervical-kissing-
carotids-1
Coronal MIP of aberrant medial course
of the carotids arteries showing the
internal carotids arteries nearly
touching at the C2 level.
An Aberrant Cervical Internal Carotid Artery in the Mouth
http://amjmed.org/an-aberrant-internal-carotid-artery-in-the-mouth/
Skull base 360°- part 1
In this kinking of ICA also Prof.Mario
Sanna uses very flexible ICA stents
Relation of Eustachian tube & looping of
parapharyngeal carotid & styloid process
Skull base 360°- part 1
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The external carotid artery passes deeply to the digastric and stylohyoid
muscles, but superficially to the stylopharyngeus and styloglossal muscle
when running toward the parotid gland (Janfaza et al. 2001 ) .
Intratemporal carotid = Horizontal
carotid[= Petrous carotid] + Vertical
carotid
Skull base 360°- part 1
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Endoscopic view of the eustachian tube orifice
(arrow).- Note Internal carotid artery
Skull base 360°- part 1
In Infra-temporal fossa approach
The full course of the intratemporal internal carotid artery has
been freed. AFL Anterior foramen lacerum, CF Carotid foramen, CL
Dura
overlying the clivus area, ICA(h) Horizontal segment of the
internal
carotid artery, ICA(v) Vertical segment of the internal carotid
artery,
MN Stump of the mandibular nerve
Drilling of the clivus has been completed. C Basal
turn of the
cochlea (promontory), FN(m) Mastoid segment
of the facial nerve,
FN(t) Tympanic segment of the facial nerve, GG
Geniculate ganglion,
GPN Greater petrosal nerve, ICA Internal carotid
artery, RW Round window
Pterygoid trigone – just anterior to foramen lacerum in
both photos is Pterygoid trigone
Skull base 360°- part 1
Note the Cochlea basal turn anterior
wall in left photo
Note that the basal turn of the cochlea (BT) starts to curve
superiorly near the internal carotid artery (ICA), a short distance
from
the level of the round window.
In most cases, the medial aspect of the horizontal
portion of the internal carotid
artery is not covered by bone, but simply by dura.
GSPN bisects the Petrous carotid & V3 and
Vertical part of Facial nerve bisects Jugular bulb
In most cases, the medial aspect of the horizontal
portion of the internal carotid
artery is not covered by bone, but simply by dura.
Post-operative vasospasm of laceral segment [ carotid
mobilization done for tumor removal ]
Paraclival carotid
TG ( Trigeminal ganglion ) is lateral to
Paraclival carotid
Infrapetrous Approach
Carotid-Clival window – Mid clivus
a. Petrosal face
b.Clival face
After drilling the carotid canal what we see is endosteal layer ,
not directly the ICA – Dr.Janakiram
Subperiosteal/Subadventitial Dissection
Subperiosteal/subadventitial dissection is accomplished for tumors that involve the ICA to a greater extent,
such as C2 glomus tumors and meningiomas (Fig. 15.24a, b). In general, dissection of the tumor from the
artery is relatively easier and safer in the vertical intrapetrous segment, which is thicker and more accessible
than the horizontal intrapetrous segment. A plane of cleavage between the tumor and the artery should be
found first. In most cases, the tumor is attached to the periosteum surrounding the artery. Dissection is better
started at an area immediately free of tumor. Aggressive tumors may, however, extend even to the adventitia
of the artery and subadventitial dissection may be needed. This should be done very carefully in order to
avoid any tear to the arterial wall, which can become weakened (Fig. 15.25), with the risk of subsequent
blowout.
Fig. 15.25 A case of left glomus jugulare tumor in our early experience.
Subadventitial dissection has been performed because the artery had
been so weakened after the tumor removal. Although the patient had no
relevant complications postoperatively, such excessive manipulation is
better avoided and permanent balloon occlusion or stenting are preferably
tried preoperatively.
Meckels cave - Trigeminal notch at
petrous apex
Carotid nerve
Petrolingual ligament [ PLL ] &
Foramen Lacerum [ FL ]
Lingula of sphenoid
Lingula of sphenoid
Lingula of sphenoid
red asterisk = lingula of the
sphenoid
black arrowhead = lingula of the
sphenoid
PLL- Petrolingual ligament - considered as a
continuation of the periostium of the carotid canal
(Osawa et al. 2008 ) .
Infrapetrous Approach
Carotid-Clival window – Mid clivus
a. Petrosal face
b.Clival face
Skull base 360°- part 1
“Front door” to Meckel’s cave
PLL - It can be considered
the border between the horizontal and cavernous portions of the
internal carotid artery.
Nerves in lateral wall of cavernous in
JNA case
Foramen lacerum - The petrous ICA then curves upward above the
foramen lacerum (FL), thus giving the anterior genu. The segment above the FL is not
truly intrapetrous, and it has been called the lacerum segment by some authors
(Bouthillier et al. 1996 ) . These segments, the anterior genu and the anterior vertical
segment, are placed above the FL, and the artery does not cross the foramen. In this
sense, it is better called the supralacerum segment (Herzallah and Casiano 2007 ) .
Anatomically, the FL is an opening in the dry skull that in life is fi lled by fi
brocartilagineous tissue (fi brocartilago basalis).
AFL = Anterior foramen
lacerum
* [ black asterisk ] = foramen
lacerum
Petrolingual area = foramen
lacerum
Vidian artery – origin from Laceral
segment
1. The foramen lacerum (FL) is located lateral to the floor of the sphenoid sinus at the
level of the spheno-petro-clival confuence.
2. In respect to the FL, the JT is postero-medially located. Therefore to
access the jugular tubercle from anteriorly a complete exposure of the foramen
lacerum is needed.
black asterisk foramen lacerum , JT jugular tubercle, HC hypoglossal canal
PLL = INFERIOR SPHENOPETROSAL LIGAMENT
ACP anterior clinoid process, APCF anterior petroclinoid fold, DS dorsum sellae, ICF interclinoid
fold, PF pituitary fossa, PLL petrolingual ligament (inferior sphenopetrosal ligament),
PPCF posterior petroclinoid fold, PS planum sphenoidale, SSPL superior sphenopetrosal
ligament (Gruber’s ligament), TS tuberculum sellae, black asterisk middle clinoid process
Parasellar carotid
Parasellar carotid – shrimp shaped
It covers four segments of the ICA: (1) the hidden segment; (2) the inferior horizontal segment;
(3) the anterior vertical segment, and (4) the superior horizontal segment. The hidden segment is
located at the level of the posterior sellar floor and includes the posterior bend of the ICA. The
inferior horizontal segment appears short due to the perspective view, but is the longest segment
of the intracavernous ICA. It courses along the sellar floor. The anterior vertical segment
corresponds to the convexity of the C- shaped parasellar protuberance. The superior horizontal
segment includes the clinoidal segment which courses medially to the optic strut, is anchored by
the proximal and distal dural ring and continues in the subarachnoid portion of the vessel.
Retro, Infra, Presellar prominences
A) Cadaveric dissection image taken within the sphenoid sinus, with removal of bone over the lateral sphenoid wall.
The paraclival carotid artery (PCA) enters the base of the sphenoid sinus and runs in a vertical direction. At
approximately the level of the V2 (maxillary division of trigeminal nerve) the carotid artery then enters the cavernous
sinus and becomes the intracavernous carotid artery (CCA). Once the artery enters the cavernous sinus it continues to
ascend for a short distance, called the vertical portion of the CCA (V. CCA), before turning anteriorly at the posterior
genu of the CCA (P. Genu CCA). This posterior genu corresponds to the floor of the sella. The artery then runs
horizontally as the horizontal portion of the CCA (H. CCA), before reaching the anterior
Skull base 360°- part 1
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http://www.slideshare.net/INUB/endoscopic-anatomy-and-approaches-of-the-
cavernous-sinus-cadaver-study- Endoscopic view of the right cavernous sinus and its
neurovascular relations, demonstrating the triangular area formed by the medial
pterygoid process laterally, the parasellar ICA medially and the vidian nerve inferiorly
at the base. III oculomotor nerve, V1 ophthalmic nerve, V2 maxillary nerve, V3
mandibular nerve, VI abducens nerve, C clivus, ICA-Sa anterior bend of the internal
carotid artery–parasellar segment, ICA-Sp posterior bend of the internal carotid
artery–parasellar segment, ICA-C paraclival segment of the internal carotid artery, ICA-
L lacerum segment of the internal carotid artery, ICA-P petrous segment of the
internal carotid artery, PG pituitary gland, VC vidian canal, VN vidian nerve
Skull base 360°- part 1
Skull base 360°- part 1
Branches of cavernous carotid
1. Meningohypophyseal trunk
2. Inferolateral trunk
The anterior lobe of the pituitary gland is mainly fed by the superior hypophyseal
arteries while the posterior lobe is fed mainly by the inferior hypophyseal artery.
Branches of Intracranial
carotid
1. Superior hypophyseal Artery
Superior Hypophyseal Arteries
[ SHAs ]
The anterior lobe of the pituitary gland is mainly fed by the superior
hypophyseal arteries while the posterior lobe is fed mainly by the inferior
hypophyseal artery.
Superior Hypophyseal Arteries [ SHAs ]
- more commonly arise from the paraclinoid ICA - In rare cases SHAs originate
from the intracavernous segment of the ICA
Skull base 360°- part 1
Meningohypophyseal trunk
The MHT is traditionally described as having three branches:
1. the inferior hypophyseal artery, IHA
2. the dorsal meningeal artery (also called the dorsal clival artery) DMA, and
3. the tentorial artery (also called the Bernasconi-Cassinari artery) BCA .
Skull base 360°- part 1
At superior part of Siphon carotid , SHA arises where as
inferior part of Siphon carotid MHT [ Inferior
hypophyseal artery ] arises
DMA main feeder of dorellos
segement of 6th nerve
DMA main feeder of dorellos
segement of 6th nerve
Inferolateral trunk
Inferolateral trunk
In most cases ILT passes superiorly to the
abducens nerve (Inoue et al. 1990 ;
Jittapiromsak et al. 2010 ) .
In most cases ILT passes superiorly to the
abducens nerve (Inoue et al. 1990 ; Jittapiromsak et al. 2010 ) .
Cholesterol granuloma
cholesterol granuloma immediately
behind the ICA
Skull base 360°- part 1
ICA Clin.: clinoid, clinoidal
Dural rings – the ICA between upper
& lower dural ring is Clinoidal ICA
Cl clivus, ICAc cavernous portion of the internal carotid artery, ON optic nerve, PG pituitary
gland, PS planum sphenoidale, TS tuberculum sellae, yellow asterisks upper dural ring, blue
arrowheads lower dural ring, white asterisk lateral optico-carotid recess, white circle medial
optico-carotid recess, white arrow ophthalmic artery, black arrows middle clinoid process, red
arrows lateral tubercular crest, yellow arrows endocranial region corresponding to MCP
Lower dural ring is nothing but COM [ Carotico-occulomotor membrane ] - The dura
lining the inferior aspect of the anterior clinoid process forms the lower
dural ring. This ring is often incomplete on the medial side and often a venous channel
can follow the paraclinoidal ICA to the upper dural ring.
By Fronto temporal approach
lower dural ring - This ring is often incomplete on the medial side and often
a venous channel can follow the paraclinoidal ICA to the upper dural ring.
blue-sky arrow = upper dural ring,
The lower dural ring is given by the COM [ Carotid-oculomotor
membrane ] , that lines the inferior surface of the ACP. It can be visible, through a
transcranial route, only by removing the ACP. The lower dural ring is also called
Perneczky’s ring. Medially the COM blends with the dura that lines the carotid sulcus
(Yasuda et al. 2005 )
Endoscopic supraorbital view with a 30°
down-facing lens -The right portion of the
planum sphenoidale is seen from above.
Right side
Upper & lower dural rings
1.Supra Trochanteric & Infratrochanteric Triangles
2. Upper & lower dural rings
ICAcl clinoidal portion of the
internal carotid artery , The
clinoidal segment of the internal
carotid artery faces the posterior
aspect of the optic strut.
white arrowhead - paraclinoid
portion of the internal carotid
artery – after removal of
anterior clinoidal process
ICA Clin.: clinoid, clinoidal [ Observe here also – posterior border of Optico-
carotid recess is Clinoidal ICA ]
ICA Clin.: clinoid, clinoidal
ICA Clin.: clinoid, clinoidal
ICA Clin.: clinoid, clinoidal
ICA Clin.: clinoid, clinoidal
Intracranial portion of ICA [ICA i]
The mOCR is located just medial to the paraclinoidal-supraclinoidal ICA
transition and inferior to the distal cisternal segment of the ON(Labib et al. 2013 ).
Cl clivus, ICAc cavernous portion of the internal carotid artery, ON optic nerve, PG pituitary
gland, PS planum sphenoidale, TS tuberculum sellae, yellow asterisks upper dural ring, blue
arrowheads lower dural ring, white asterisk lateral optico-carotid recess, white circle medial
optico-carotid recess, white arrow ophthalmic artery, black arrows middle clinoid process, red
arrows lateral tubercular crest, yellow arrows endocranial region corresponding to MCP
Opthalmic artery – Retrograde branch of Intracranial carotid
Branches of the cavernous internal
carotid artery ( ICA ), a rare
variation: ophthalmic
artery passing through the superior
orbital fissure
In the lateral border of the chiasmatic cistern the first part of
the ICAi is visible.
Note Optic tract here which is above
Posterior clinoid process [ PCP ]
Supra-clinoidal carotid=1st part of
intracranial carotid
APAs anterior perforating arteries, ICAi intracranial portion of
the internal carotid artery, OT optic tract, SF Sylvian fi ssure,
ACA anterior cerebral artery, APAs anterior perforating arteries, FOA fronto-orbital artery,
FOV fronto-orbital vein, FPA fronto-polar artery, ICAi intracranial segment of the internal
carotid artery, MCA middle cerebral artery, OlfT olfactory tract, OlfV olfactory vein, ON optic
nerve, PS pituitary stalk, TL temporal lobe, black asterisk anterior communicating artery
ICA dividing into ACA and MCA
Skull base 360°- part 1
Optic tract [ OT ]
Skull base 360°- part 1
Pterional
CRANIOPHARYNGIOMAS-Removal corridors.
Cyst of craniopharyngioma
Skull base 360°- part 1
Surpra petrous approach
Surpra petrous window [ see the GSPN groove here ]
ET eustachian tube, GPN greater petrosal nerve, MCFd dura of the middle cranial fossa, MMA
middle meningeal artery, SPS superior petrosal surface, TI trigeminal impression, V3 third
branch of the trigeminal nerve, yellow arrow accessory middle meningeal artery, white
asterisks greater petrosal nerve groove
Infrapetrous approach
Inferior petrosal sinus is superior to jugular tubercle &
hypoglossal canal is inferior to jugular tubercle
Infratemporal fossa [=intact cochlear
approach – Dr.Morwani ] type B approach
The pontomedullary junction.
1. The exit zones of the hypoglossal and abducent nerves are at
the same level [ same vertical line when view from Transclival
approah ( through lower clivus ) ]
2. The abducent nerve exits from the pontomedullary junction, and ascends
in a rostral and lateral direction toward the clivus.
Skull base 360°- part 1
In infrapetrous approach there are chances of injury to 6th nerve [ in dorello’s
canal medial to paraclival carotid ] & 12th nerve
When we are drilling lower clivus – lateral to
hypoglossal canal we get Jugular fossa
Adenoid cycstic carcinoma clivus -- Just look at the carotid. .The paraclival both sides
360 degree encased..look at the mass eroding Petros apex going above horizontal
carotid above the meckels cave..we need a trans cavernous..trans supra Petros. .infra
Petros. . App..
Sub frontal approach
Fig. 2.1 Drawing showing the skin incision (red line), the craniotomy
and the microsurgical intraoperative view of the subfrontal
unilateral approach. This approach provides a wide intracranial
exposure of the frontal lobe and easy access to the optic
nerves, the chiasm, the carotid arteries and the anterior communicating
complex
Fig. 2.4 Intraoperative microsurgical photograph showing contralateral
extension of the tumor (T) dissected via a unilateral subfrontal
approach. Note on the left side the falx cerebri (F) and
the mesial surface of the left frontal lobe (FL)
Fig. 2.5 Drawing showing the skin incision (red line), the craniotomy
and the microsurgical anatomic view of the subfrontal bilateral
route. This approach provides a wide symmetrical anterior
cranial fossa exposure and easy access to the optic nerves, the
chiasm, the carotid arteries and the anterior communicating arteries
complex
Supraorbital approach - Fig. 3.2 Illustrations comparing the incision and
bony exposure in a supraorbital craniotomy with those in a pterional craniotomy. a
The supraorbital craniotomy utilizes the subfrontal corridor and involves a frontobasal
burr hole and removal of a small window in the frontal bone. b The pterional
craniotomy utilizes a frontotemporal incision and removal of the frontal and temporal
bones andsphenoid wing. The pterional craniotomy primarily exploits the sylvian
fissure
Frontotemporal approach
Fig. 4.6 a Craniotomy. b When the flap has been removed the
lesser wing of the sphenoid is drilled down to optimize the most
basal trajectory to the skull base. c Dural opening. DM dura
mater, FL frontal lobe, MMA middle meningeal artery, LWSB
lesser wing of the sphenoid bone, SF sylvian fissure, TL temporal
lobe, TM temporal muscle, ZPFB zygomatic process of the frontal bone
Fig. 4.8 Intradural exposure; right approach. Before (a) and after (b) opening of the
Sylvian fissure. A1 first segment of the anterior cerebral artery, AC anterior clinoid, FL
frontal lobe, HA Heubner’s artery, I olfactory tract, III oculomotor nerve, ICA internal
carotid artery, LT lamina terminalis, M1 first segment of the middle cerebral artery,
MPAs perforating arteries, ON optic nerve, P2 second segment of the posterior
cerebral artery, PC posterior clinoid, PcoA posterior communicating artery, SF sylvian
fissure, TL temporal lobe, TS tuberculum sellae
Fig. 4.9 Intradural exposure; right approach. a Instruments enlarging the optocarotid
area. b Displacing medially the posterior communicating artery, exposing the
contents of the interpeduncular cistern. AC anterior clinoid, AchA anterior choroidal
artery, BA basilar artery, FL frontal lobe, ICA internal carotid artery, III oculomotor
nerve, OA left ophthalmic artery, ON optic nerve, OT optic tract, P2 second segment of
the posterior cerebral artery, PC posterior clinoid, PcoA posterior communicating
artery, Ps pituitary stalk, SCA superior cerebellar artery, SHA superior hypophyseal
artery, TE tentorial edge, TL temporal lobe
Fig. 4.10 Intradural exposure; right approach; enlarged view. A1 first segment of the anterior
cerebral artery, A2 second segment of the anterior cerebral artery, AC anterior clinoid, AcoA
anterior communicating artery, BA basilar artery, FL frontal lobe, HA Heubner’s artery, ICA
internal carotid artery, III oculomotor nerve, LT lamina terminalis, M1 first segment of the middle
cerebral artery, OA left ophthalmic artery, ON optic nerve, P2 second segment of the posterior
cerebral artery, PC posterior clinoid, PcoA posterior communicating artery, SCA superior cerebellar
artery, SHA superior hypophyseal artery, TE tentorial edge, TL temporal lobe, TS tuberculum sellae
Fig. 4.11 Intradural exposure; right approach; close-up view ofthe interpeduncular fossa. AchA
anterior choroidal artery, BAbasilar artery, DS dorsum sellae, III oculomotor nerve, IV
trochlear nerve, P1 first segment of the posterior cerebral artery,P2 second segment of the
posterior cerebral artery, PC posteriorclinoid, PcoA posterior communicating artery, Ps pituitary
stalk, SCA superior cerebellar artery, TE tentorial edge
Endoscope-assisted microsurgery [ 45° endoscope in a corridor
between the carotid artery and the oculomotor nerve ]-- Fig. 4.12
Intradural exposure; right approach; microsurgical (a) and endoscopic (b–d) views. AchA
anterior choroidal artery, BA basilar artery, C clivus, FL frontal lobe, ICA internal carotid artery, III
oculomotor nerve, ON optic nerve, P1 first segment of the posterior cerebral artery, P2 second
segment of the posterior cerebral artery, PC posterior clinoid, PCA posterior cerebral artery, PcoA
posterior communicating artery, SCA superior cerebellar artery, TE tentorial edge, TL temporal
lobe, Tu thalamoperforating artery; green dotted triangle area for entry of the endoscope into
the interpeduncular fossa
Fig. 4.12 Intradural exposure; right approach; microsurgical (a) and endoscopic (b–d) views.
AchA anterior choroidal artery, BA basilar artery, C clivus, FL frontal lobe, ICA internal carotid
artery, III oculomotor nerve, ON optic nerve, P1 first segment of the posterior cerebral artery, P2
second segment of the posterior cerebral artery, PC posterior clinoid, PCA posterior cerebral
artery, PcoA posterior communicating artery, SCA superior cerebellar artery, TE tentorial edge, TL
temporal lobe, Tu thalamoperforating artery; green dotted triangle area for entry of the
endoscope into the interpeduncular fossa
Fig. 4.13 Intradural exposure; right approach; microsurgical (a)
and endoscopic omolateral (b) and contralateral (c) views. A1 first segment of the anterior
cerebral artery, AC anterior clinoid, ICA internal carotid artery, FL frontal lobe, III oculomotor
nerve, LT lamina terminalis, M1 first segment of the middle cerebral artery, OA left ophthalmic
artery, ON optic nerve, PcoA posterior communicating artery, SHA superior hypophyseal artery, TE
tentorial edge, TS tuberculum sellae
Fig. 4.13 Intradural exposure; right approach; microsurgical (a)
and endoscopic omolateral (b) and contralateral (c) views. A1 first segment of the anterior
cerebral artery, AC anterior clinoid, ICA internal carotid artery, FL frontal lobe, III oculomotor
nerve, LT lamina terminalis, M1 first segment of the middle cerebral artery, OA left ophthalmic
artery, ON optic nerve, PcoA posterior communicating artery, SHA superior hypophyseal artery, TE
tentorial edge, TS tuberculum sellae
Fronto-temporal orbitozygomatic
transcavernous approach
COM= Caratico-occulomotor
membrane , DR = dural ring
Skull base 360°- part 1
Skull base 360°- part 1
Division of PComA
Fig. 4.15 Microsurgical view; extradural anterior
clinoidectomy. a Exposure and drilling of the anterior clinoid process
and optic canal under microscope magnification. b Widened space after complete removal of
the AC. AC anterior clinoid, eON extracranial intracanalar optic nerve, FD frontal dura, ICA
internal carotid artery, iON intraorbital optic nerve, LWSB lesser wing of sphenoid bone, OC optic
canal, OR orbit roof, SOF superior orbital fissure, TD temporal dura
Fig. 4.16 Microsurgical view; intradural anterior clinoidectomy. a, b After the dura above the
anterior clinoid process has been transected in a “T” shape (a), we usually drill always parallel
tothe optic nerve and to the carotid artery (b). c The distal ring is finally exposed. A1
precommunicating anterior cerebral artery, AC anterior clinoid, AchA anterior choroid artery, Ch
optic chiasm, DR distal ring, fl falciform ligament, FL frontal lobe, ICA internal carotid artery, M1
first tract of the middle cerebral artery, ON optic nerve, PC posterior clinoid, PCOA posterior
communicating artery, TS tuberculum sellae
Fig. 4.16 Microsurgical view; intradural anterior clinoidectomy. a, b After the dura above the
anterior clinoid process has been transected in a “T” shape (a), we usually drill always parallel
tothe optic nerve and to the carotid artery (b). c The distal ring is finally exposed. A1
precommunicating anterior cerebral artery, AC anterior clinoid, AchA anterior choroid artery, Ch
optic chiasm, DR distal ring, fl falciform ligament, FL frontal lobe, ICA internal carotid artery, M1
first tract of the middle cerebral artery, ON optic nerve, PC posterior clinoid, PCOA posterior
communicating artery, TS tuberculum sellae
Posterior clinoidectomy
FTOZ – Fronto-temporal
orbitozygomatic approach
FTOZ – Fronto-temporal
orbitozygomatic approach
Subtemporal approach
Fig. 7.13 a Intraoperative photograph shows good exposure of the left tentorial anterior and middle incisura
obtained through the pretemporal and subtemporal corridors. In this patient the
basilar apex is well above the superior margin of the dorsum sellae. b Same patient. A more lateral exposure
showing the pontomesencephalic junction surface and the neurovascular structures in the ambient cistern. c
Intraoperative photograph of another patient showing structures in the left lateral incisural space from the
subtemporal corridor. d Same patient. More lateral view. e Same patient. More posterior exposure. The lifting
of the free edge of the tentorium shows the trochlear nerve entering the tentorium. The junction between the
P2a and P2p segments (P2a, P2p) of the posterior cerebral artery is shown. ACA anterior cerebralartery, AChA
anterior choroidal artery and tiny perforating vessels, BA basilar artery, DS dorsum sellae, FET free edge of
tentorium, ICA internal carotid artery, LM Liliequist’s membrane, LON left optic nerve, ON oculomotor nerve, OT
optic tract, PCA posterior cerebral artery, PComA posterior communicating artery, PLChA posterolateral
choroidal artery arising from the P2a–P2p junction, PS pituitary stalk, RON right optic nerve, SCA superior
cerebellar artery, TN trochlear nerve in the arachnoidal covering
Fig. 7.13 a Intraoperative photograph shows good exposure of the left tentorial anterior and middle incisura
obtained through the pretemporal and subtemporal corridors. In this patient the
basilar apex is well above the superior margin of the dorsum sellae. b Same patient. A more lateral exposure
showing the pontomesencephalic junction surface and the neurovascular structures in the ambient cistern. c
Intraoperative photograph of another patient showing structures in the left lateral incisural space from the
subtemporal corridor. d Same patient. More lateral view. e Same patient. More posterior exposure. The lifting
of the free edge of the tentorium shows the trochlear nerve entering the tentorium. The junction between the
P2a and P2p segments (P2a, P2p) of the posterior cerebral artery is shown. ACA anterior cerebral artery, AChA
anterior choroidal artery and tiny perforating vessels, BA basilar artery, DS dorsum sellae, FET free edge of
tentorium, ICA internal carotid artery, LM Liliequist’s membrane, LON left optic nerve, ON oculomotor nerve, OT
optic tract, PCA posterior cerebral artery, PComA posterior communicating artery, PLChA posterolateral
choroidal artery arising from the P2a–P2p junction, PS pituitary stalk, RON right optic nerve, SCA superior
cerebellar artery, TN trochlear nerve in the arachnoidal covering
Fig. 7.13 a Intraoperative photograph shows good exposure of the left tentorial anterior and middle incisura
obtained through the pretemporal and subtemporal corridors. In this patient the
basilar apex is well above the superior margin of the dorsum sellae. b Same patient. A more lateral exposure
showing the pontomesencephalic junction surface and the neurovascular structures in the ambient cistern. c
Intraoperative photograph of another patient showing structures in the left lateral incisural space from the
subtemporal corridor. d Same patient. More lateral view. e Same patient. More posterior exposure. The lifting
of the free edge of the tentorium shows the trochlear nerve entering the tentorium. The junction between the
P2a and P2p segments (P2a, P2p) of the posterior cerebral artery is shown. ACA anterior cerebralartery, AChA
anterior choroidal artery and tiny perforating vessels, BA basilar artery, DS dorsum sellae, FET free edge of
tentorium, ICA internal carotid artery, LM Liliequist’s membrane, LON left optic nerve, ON oculomotor nerve, OT
optic tract, PCA posterior cerebral artery, PComA posterior communicating artery, PLChA posterolateral
choroidal artery arising from the P2a–P2p junction, PS pituitary stalk, RON right optic nerve, SCA superior
cerebellar artery, TN trochlear nerve in the arachnoidal covering
THE FULLY ENDOSCOPIC SUBTEMPORAL APPROACH [ from
Shahanian book ] - The traditional middle fossa subtemporal approach requires long-
standing placement of retractors on the temporal lobe; therefore, potential injury to the
temporal lobe can occur
(e.g., hematoma and edema resulting in aphasia, hemiparesis, or seizures). This concern should
not be a problem with the described approach because temporal lobe retractors are not used.
(L) a Epidermoid tumor. b Atraumatic
suction. c Brainstem. d Occulomotor (III)
nerve. e Posterior cerebral artery (PCA).
f Superior cerebellar artery (SCA). g
Trochlear (IV) nerve.
(N) a Epidermoid tumor. b Atraumatic suction. c
Left-curved tumor forceps. d Occulomotor (III)
nerve. e Posterior cerebral artery (PCA). f
Posterior communicating (PCOM) artery. g
Superior cerebellar artery (SCA).
h Brainstem. i Trochlear (IV) nerve.
Q) a Occulomotor (III) nerve. b
Internal carotid artery (ICA). c
Posterior cerebral artery (PCA).
d Superior cerebellar artery
(SCA).
(P) a Ipsilateral optic (II) nerve. b
Internal carotid artery (ICA). c
Occulomotor (III) nerve.
d Dura overlying anterior clinoid
process.
Carotid artery bleeding
Skull base 360°- part 1
Skull base 360°- part 1
Skull base 360°- part 1
SKULL BASE 360°
Above presentation is
SKULL BASE 360°-Part 1
For
SKULL BASE 360°-Part 2
Please click or copy/paste in URL or weblink area
http://www.slideshare.net/muralichandnallamoth
u/edit_my_uploads
[ Dated: 19-4-14 ]
I will update continuosly with date tag at the end as I am getting more
& more information

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Skull base 360°- part 1

  • 1. SKULL BASE 360° Below presentation is SKULL BASE 360°-Part 1 For SKULL BASE 360°-Part 2 Please click or copy/paste in URL or weblink area http://www.slideshare.net/muralichandnallamoth u/skull-base-360-part-2-39401703 [ Dated: 26-10-14 ] I will update continuosly with date tag at the end as I am getting more & more information
  • 2. Great teachers – All this is their work . I am just the reader of their books . Prof. Paolo castelnuovo Prof. Aldo Stamm Prof. Mario Sanna Prof. Magnan
  • 3. For Other powerpoint presentatioins of “ Skull base 360° ” I will update continuosly with date tag at the end as I am getting more & more information click www.skullbase360.in - you have to login to slideshare.net with Facebook account for downloading.
  • 4. Below presentation is SKULL BASE 360°-Part 1 Indetail eloborate description for each part of skullbase360 done at www.skullbase360.in » Presentation by » Dr. N. Murali Chand DLO MS (ENT) FHM » Fellowship in HIV medicine, MAMC, New Delhi » My website = www.integratedmedicine.co.in • www.skullbase360.in » Cell= +91 99496 77605
  • 9. 1. External corridor doesn’t matter except cosmesis , only internal corridor matters – so in Open approaches of skull base also use endoscope to get best results – see this video how the Dr. Dugani Suresh ; Neurosurgeon is using endoscope in Weber Fergusson incision https://www.youtube.com/watch?v=Y95Jf3u8S8o&feature=y outu.be 2. Most of the times “Don’t cross the NERVES”
  • 10. Prof. Amin Kassam CORRIDOR SURGERY • Video 1 https://www.youtube.com/watch?v=J6ji53nKQy 0 Video 2 https://www.youtube.com/watch?v=56Wt4vQ9 KgE
  • 11. External carotid artery ligation – Note at division of common carotid , external carotid artery is medial to internal carotid artery – Sometimes the division may go up very high in neck .
  • 12. Only to lesion lateral to meridian of pupil in frontal sinus we have to do osteoplastic flap The landmarks for canine fossa puncture/trephine are the intersection between a vertical line through the pupil and a horizontal line drawn through the floor of the nose.
  • 13. Enhanced T1-weighted magnetic resonance imaging (MRI), coronal section demonstrates a right nasoethmoidal lesion (adenocarcinoma) with an “hourglass” intradural extension through the ethmoidal roof. Diffuse enhancement of the dural layer (arrowheads) over the orbital roof is suspicious for neoplastic spread. The vertical lines limit the area of the dura safely resectable by a pure endoscopic approach.
  • 14. “Up & below” approach to frontal sinus
  • 15. Illustration of the septal incisions necessary to achieve good access to the entire anterior wall of the maxillary sinus for tumors either originating from this region or with a significant anterior wall attachment. (B) Cadaveric image demonstrating the access to the anterior wall (AW) of the maxillary sinus with a 70-degree diamond drill (D).
  • 17. (A) The microdebrider blade has been passed through an inferior meatal antrostomy. Note the anterior fulcrum (nasal vestibule, broken white arrow) and the posterior fulcrum (inferior meatal antrostomy, white arrow). The region of the maxillary sinus that can be cleared through this access is shaded. This shaded region is smaller with a middle meatal antrostomy. The single fulcrum of the canine fossa puncture is indicated (white arrow) (B,C,D), illustrating how the entire maxillary sinus can be accessed as the blade only has a single fulcrum.Medial , posterior & Lateral walls approached through Caldwel-luc
  • 18. The red arrows demonstrate the endonasal approach, and the green arrows represents the transmaxillary approach. The blue rectangle shows the parasellar structures. A more perpendicular angle of attack is achieved in the transmaxillary approach, and the distance to the target from this route is equal to or smaller than that in the endonasal approach. Temp.: temporal.
  • 19. Note that in the transmaxillary approach the structures in the lateral wall of the sphenoid sinus are seen in a more perpendicular way, facilitating dissection of this region.
  • 20. Close-up view of the cavernous sinus through the transmaxillary approach. Gasser.: gasserian.
  • 21. The pink and orange lines demonstrate the possible angles of maneuver in transmaxillary approach. In green is emphasized the possibilities of resection through transmaxillary approach.
  • 22. General view of the radial endoscopic accesses to the skull base --- The green arrows represent the endonasal approaches, the red arrows represent the transmaxillary approaches, and the purple arrows represent the subtemporal approaches. Note the multiple possibilities of combination of these approaches.
  • 23. Modified denkers approach - Blue dotted line shows the medial maxillary wall. (B) Panoramic view after removing the medial maxillary wall. Yellow dotted line shows the connected nasal cavity with maxillary sinus the maxillary sinus.
  • 24. Schematic demonstrating how the removal of the lateral aspect of the piriform overture (in the red circle) enables a wider approach (the green cone compared with the yellow cone) to the lateral regions (pterygopalatine and infratemporal fossa).
  • 25. Use combination of approaches when ever it is necessary - Combined Transmastoid Middle Cranial Fossa Approach
  • 26. Rt lower cranial nerve shwannoma, which approach will be better ,which approach will be better considering this side is dominant sinus.
  • 27. Answer • Amit Keshri says - eight nerve was normal,so was 7th,removed tumor completely with retrolab approach and to get space,the sigmoid plate was decompressed and sinus retracted posteriorly after RMSO [ Retro mastoid sub-occipital ] craniotomy without opening dura posteriorioly. • Murali Chand Nallamothu For lower cranial nerve schawnnoma POTS approach is the best - but here you are saying it is dominent sinus , no need to sacrifice sigmoid sinus -- so in this case we can use extended translabyrinthine approach for the AFB area part & at carotid canal area part of the tumor can be removed by externally which is included in the lower C - shaped incision • Murali Chand Nallamothu if the 8 th nerve is good we can try retrolabyrinthinne & retrosigmoid approach & take the help of endoscope. • Post-op :
  • 28. Posterior wall of maxillary sinus Periosteum after removal of posterior bony wall of maxillary sinus – this periosteum must be removed in JNA
  • 30. Anteriorly MPP & LPP are fused & posterioly only they are divided .
  • 31. Anteriorly MPP & LPP are fused & posterioly only they are divided .
  • 33. Erosion of right greater wing of sphenoid in a case of maxillary carcinoma
  • 35. Medial pterygoid is in line with lateral wall of Sphenoid -- The superior vertical limb represents the paraclival ascending carotid and the descending vertical limb is represents the medial pterygoid plate. The horizontal bar of the ‘H’ is represented by the sphenoid sinus floor.
  • 36. Lateral part of Posterior choanae is MPP
  • 37. ET is just posterior to MPP
  • 38. Lateral part of Posterior choanae is MPP
  • 39. Medial pterygoid is in line with Paraclival carotid
  • 40. Tracking of infraorbital nerve leads to V2 & tracking of V2 leads to Trigeminal ganglion/ Middle cranial fossa [ one of the best way to track middle crannial fossa is to track V 2 ]
  • 42. Infraorbital groove near inferior orbital fissure – If we drill supero-lateral to infraorbital nerve it is nothing but Inferior orbital fissure .
  • 43. Infraorbital groove near inferior orbital fissure – If we drill supero-lateral to infraorbital nerve it is nothing but Inferior orbital fissure .
  • 45. Inferior orbital foramen continues as pterygomaxillary fissure .
  • 47. One line along Vidian nerve & another line along V2
  • 50. Lateral to LPP & infra-orbital nerve [ or V2 ] is Infratemporal fossa
  • 51. One transverse line from Vidian nerve connecting vertical line of V 2 & another transverse line from V2
  • 52. The space above transverse line of Vidian nerve is Pterygoid Recess of sphenoid – Read the CT – scan/ Plane the surgery by using these lines
  • 53. The space above transverse line of V2 is Middle cranial fossa ( Meckel’s cave ) – Read the CT – scan/ Plane the surgery by using these lines
  • 57. Pterygopalatine fossa. A, V2 (blue dotted line) coming out from the foramen rotundum; B, green-yellow dotted line shows the pterygopalatine ganglion; C, yellow dotted line shows the vidian nerve; D, red dotted line shows the sphenopalatine artery; E, light blue dotted line shows the great palatine nerve; F, white dotted line showing the infraorbital artery.
  • 58. EC – Ethmoidal crest – left nose
  • 59. PVC , VC & FR are in 45 degree angle line
  • 63. Tracking of infraorbital nerve leads to V2 & tracking of V2 leads to Trigeminal ganglion/ Middle cranial fossa [ one of the best way to track middle crannial fossa is to track V 2 ]
  • 66. Endoscopic view of foramen rotundum area
  • 70. Lateral pterygoid muscle devides internal maxillary artery into 3 parts
  • 71. 1. The maxillary artery & Buccal nerve enters the infratemporal fossa between the superior and inferior head of the lateral pterygoid muscles. 2. Lingual nerve & Inferior alveolar nerve comes between medial pterygoid & lateral pterygoid mucles .
  • 72. .
  • 73. Anteriorly lingual nerve & posteriorly Inferior Alveolar nerve coming lateral to medial pterygoid muscle
  • 74. Forceps behind IAN Forceps behind LN
  • 75. IAN = Inferior alveolar nerve
  • 76. Triangle formed by temporalis muscle , MPM & LPM Mandibulotomy approach Endospic view
  • 77. Post-maxillectomy “Fat pad” over temporalis muscle – which is seen as Fat Pad [ FP ] in the triangle formed by temporalis mucle , MTM & LPM endoscopically
  • 78. Internal carotid artery going medial & posterior to medial pterygoid muscle into Parapharyngeal space & becoming Parapharyngeal carotid
  • 79. Internal carotid artery going medial & posterior to medial pterygoid muscle into Parapharyngeal space & becoming Parapharyngeal carotid
  • 80. After removing the LPM you will see Tensor veli palatini muscle (TVPM) coming vertically downwards from anterior surface of ET , protecting parapharyngeal carotid & after TVPM , thick Stylopharyngeal apneurosis (SPHA ) present ANTERIOR to Parapharyngeal carotid [ So 2 structures ( TVPM & SPHA ) protecting parapharyngeal carotid ]
  • 81. After removing the LPM you will see Tensor veli palatini muscle (TVPM) coming vertically downwards from anterior surface of ET , protecting parapharyngeal carotid & after TVPM thick Stylopharyngeal apneurosis present ANTERIOR to Parapharyngeal carotid -- Attached to this ET cartilage [ TP/ET attachment ] is the tensor palatini (TP) fibrous aponeurosis (solid white line) with its muscle fibers seen below (broken white line).
  • 82. Hand model -- left hand = medial & lateral pterygoid right hand = index is parapharyngeal carotid , middle is IJV , ring is styloid & stylopharyngeal muscles , thumb is horizontal carotid
  • 94. Internal carotid artery going medial & posterior to medial pterygoid muscle into Parapharyngeal space & becoming Parapharyngeal carotid
  • 95. Post-styloid compartment = carotid space
  • 100. Sphenoid osteum present at the juction of upper 2/3rd & lower 1/3rd junction of Superior turbinate – this became very useful to me in extensive fungal sinusitis with polyposis & bleeding.
  • 101. Three sequential indentations are made with the blunt end of the 4-mm microdebrider blade starting at the medial upper limit of the posterior bony choana and moving directly superiorly medial to the cut edge of the superior turbinate.
  • 103. L-OCR – Triangle 1. Upper boarder – Optic nerve & Opthalmic artery 2. Posterior boarder – Clinoidal carotid 3. Lower boarder – 3rd N. [ COM – Carotico-Occulomotor membrane seperates 3rd N from Clinoidal carotid ] [ 6th N. & 4th N. & V1 present inferior to 3rd N. ]
  • 104. The optic strut has two neural- facing surfaces( yellow dotted lines) and one vascular-facing surface (red dotted line). [ COM – Carotico-Occulomotor membrane seperates 3rd N from Clinoidal carotid ]
  • 106. The bone of the anterior clinoid (AC) process has been left in place, positioned within the lateral opticocarotid recess. L-ocr is the space in Optic strut - not the space in Anterior clinoid process
  • 107. classification of the ophthalmic artery types http://www.springerimages.com/Images/MedicineAndPublicHealth/1- 10.1007_s10143-006-0028-6-1 a = intradural type, b = extradural supra-optic strut type [ Optic strut = L-OCR ] c = extradural trans-optic strut type on optic nerve, pr proximal ring, cdr carotid dural ring= upper dural ring , ica internal carotid artery I think this variation is type c
  • 108. In both type a = intradural type, b = extradural supra-optic strut types Opthalmic foramen is in Optic canal
  • 109. In Type c = extradural trans-optic strut type , the Opthalmic foramen in Optic strut
  • 110. L-ocr is the space in Optic strut - not the space in Anterior clinoid process Note Optic strut Note Optic strut - Right Optic nerve Anterio-superior view
  • 111. Pneumatization of anterior clinoid process – in various planes + onodi cell on both sides of sphenoid [ when transverse septum present in sphenoid it is onodi cell ] + sphenoid recess on left side between V2 & VN .
  • 112. The same cadaver photo what you are seeing in CT scan above – Note the supraoptic pneumatisation [ present in anterior clinoid process ] in an onodi cell .
  • 113. ICAcl clinoidal portion of the internal carotid artery , The clinoidal segment of the internal carotid artery faces the posterior aspect of the optic strut [L-OCR ]
  • 114. Red ring – Pneumatization in Optic strut – which is nothing but L-OCR
  • 115. M-OCR
  • 116. Sagittal sections and superior views of the sellar region showing the optic nerve and chiasm, and carotid artery. The prefixed chiasm is located above the tuberculum. The normal chiasm is located above the diaphragma. The postfixed chiasm is situated above the dorsum.
  • 117. 1. M-OCR is nothing but Middle Clinoid Process [ indicated by Green Button in both photos ] 2. M-OCR is the junction point of clinoidal carotid & Supra- clinoidal carotid
  • 118. The mOCR is located just medial tothe paraclinoidal-supraclinoidal ICA transition and inferior to the distal cisternal segment of the ON(Labib et al. 2013 ). Cl clivus, ICAc cavernous portion of the internal carotid artery, ON optic nerve, PG pituitary gland, PS planum sphenoidale, TS tuberculum sellae, yellow asterisks upper dural ring, blue arrowheads lower dural ring, white asterisk lateral optico-carotid recess, white circle medial optico-carotid recess, white arrow ophthalmic artery, black arrows middle clinoid process, red arrows lateral tubercular crest, yellow arrows endocranial region corresponding to MCP
  • 119. 1. The mOCR is placed at the confluence of the sella, tuberculum sellae, carotid protuberance, optic canal and planum sphenoidale. The mOCR corresponds to the lateral extent of the tuberculum sellae. ---- white asterisk lateral opticocarotid recess, white circle medial opticocarotid recess --- 2. The mOCR is located just medial to the paraclinoidal-supraclinoidal ICA transition and inferior to the distal cisternal segment of the ON (Labib et al. 2013 ).
  • 120. Limits of the bone resection – Inner ring in below photo • Posterior ethmoidal arteries • Medial OCRs
  • 122. Pituitary present between “ four blues” SIS – superior intercavernous sinus & IIS – inferior intercavernous sinus
  • 123. 1. Note ASIS & PSIS 2. Note Subarachnoid space at antero-superior area , which is the potential CSF leak area in pituitary surgery . Usually the DS originates some millimeters below the TS.
  • 124. PSIS – Posterior superior intercavernous sinus ASIS & PSIS together called CIRCULAR SINUS
  • 127. Right cavernous sinus dissection. The quadrilateral delimits the right cavernous sinus area. a Before periosteal layer removal. b After periosteal layer removal. c Cavernous sinus compartments. L = Lateral; AI = antero- inferior; PS = posterosuperior compartment of the cavernous sinus (the medial is a virtual space in continuity with the AI and PS). CS divided into four virtual compartments: 1. medial, 2. lateral, 3. posterosuperior, and 4. anteroinferior Medial and posterosuperior compartments are in strict continuity and do not contain nerves, representing a surgical corridor without risk of neural damage. The anteroinferior and lateral compartments contain the abducens nerve and, as surgical corridors, they are exposed to the riskof injury to the VIth nerve.
  • 128. Clivus 1. Upper Clivus 2. Middle Clivus 3. Lower Clivus
  • 129. Basi occiput & basi sphenoid
  • 130. Groove for medulla on Lower Clivus [ = Basi Occiput ]
  • 131. The 6 linear landmarks of the PCF superimposed on a midsagittal T1-weighted MR imaging from a patient with CMI: herniation (HR), McRae line (MC), clivus (CL), Twining line (TW), cerebellum (CR), and supraocciput (SO). http://www.ajnr.org/content/34/9/1758.figures- only?cited-by=yes&legid=ajnr;34/9/1758
  • 132. 1. Upper clivus – Upto 6th nerve entry dorello’s canal (petro-clival junction) 2. Middle clivus – from 6th nerve to jugular foramen 3. Lower clivus – from jugular foramen to foramen magnum
  • 133. Pneumatization of the sphenoid sinus
  • 134. The middle third (M. 1/3rd) begins at the sella floor (SF) and extends to the floor of the sphenoid sinus (SSF), and the lower third (L. 1/3rd) extends from the floor of the sphenoid sinus to the foramen magnum (FM).
  • 135. Pregnant of upper clivus is Sella
  • 136. Infrapetrous Approach Carotid-Clival window – Mid clivus a. Petrosal face b.Clival face
  • 137. See the lower clivus relation to the cochlea
  • 138. In conchal sphenoid surgical landmarks – 1. posterior end of vomer or keel of sphenoid tells about the position of pituitary 2. lateral boarder of posterior choana [ or MPP ]tells about paraclival carotid & sellar carotid C-SHAPE convex is lateral to this line 3. posterior lower boarder of vomer is at the junction of middle & lower 1/3rd clivus & it is exactly at foramen lacerum –my understanding
  • 139. See the relationship between lower boarder of posterior end of vomer & clivus – vomer lower boarder is at junction of mid & lower clivus – my understanding
  • 141. Anterior cranial fossa dura Posterior cranial fossa dura
  • 142. Very rare specimen..The vbj is far inferior to floor of sphenoid sinus
  • 143. The foramen lacerum (FL) is located lateral to the floor of the sphenoid sinus at the level of the spheno-petro-clival confuence. JT jugular tubercle, HC hypoglossal canal – addFig 3.78 also
  • 144. Infrapetrous Approach Carotid-Clival window – Mid clivus a. Petrosal face b.Clival face
  • 145. When we are drilling lower clivus – lateral to hypoglossal canal we get Jugular fossa
  • 146. Inferior clival line (Fernandez-Miranda et al. 2012 ) The longus capitis and rectus capitis anterior muscle attach on the inferior surface of the clivus. Below the RCAM the occipito-cervical joint capsule lies. The area of attachement of the RCAM has been named inferior clival line (Fernandez-Miranda et al. 2012 ) and correspond to the supracondylar groove (that is a landmark for the hypoglossal canal).
  • 148. Note CL [ Lower clivus ] in these photos after drilling of cochlea
  • 149. Note CL [Lower clivus ] in these photos after drilling of cochlea The clivus bone (CL) can be seen medial to the internal carotid artery (ICA). JB Jugular bulb In the lower part of the approach, the glossopharyngeal nerve (IX) can be seen. V Trigeminal nerve, VIII Cochlear nerve, AICA Anterior inferior cerebellar artery, CL Clivus bone, DV Dandy’s vein, FN Facial nerve, FN(m) Mastoid segment of the facial nerve, FN(t) Tympanic segment of the facial nerve, GG Geniculate ganglion, ICA Internal carotid artery, JB Jugular bulb, MFD Middle fossa dura, SCA Superior cerebellar artery, SS Sigmoid sinus
  • 150. Note CL [Lower clivus ] in these photos after drilling of cochlea BT- basal turn of the cochlea Fig. 8.34 The bone medial to the internal carotid artery (ICA) has been drilled and the clivus bone (CL) has been reached. FN Facial nerve, JB Jugular bulb
  • 151. Note CL [Lower clivus ] in these photos after drilling of cochlea Note cochlear aqueduct [ CA ] Here ICA is vertical part of carotid infront to cochlea – this is not paraclival carotid
  • 152. Note CL [ clivus ] in these photos after drilling of cochlea
  • 153. Note CL [Lower clivus ] in these photos after drilling of cochlea Note the contralateral vertebral artery [ CVA ] in below photo
  • 154. Lower clivus in Infratemporal fossa approach
  • 157. PVC – is occupied by Ascending palatine artery (APA)
  • 158. Craniopharyngioma removal - Lilliquest membrane & Basillar artery
  • 160. V 3 falls like niagara falls from middle cranial fossa to infratemporal fossa 90 degrees away from V1 & V2 – it is anterior to all the 3 structures , Petrous carotid & ET tube & Parapharyngeal carotid
  • 164. MMA
  • 166. IAN = Inferior alveolar nerve
  • 168. My forceps touched the lingual nerve , posterior to this LN is Inferior alveolar nerve – These two nerves present in triangle formed by medial pterygoid , lateral pterygoid & temporalis muscle
  • 172. Schematic diagram for infratemporal fossa approach
  • 173. Sometimes V3 can be seen in the sphenoid sinus – in “pneumosinus dilatans multiplex”
  • 174. The greater wing of sphenoidal is almost completely pnematised. So is the temporal bone on the left.the Left carotid can be traced from the middle ear to the sphenoid - in “pneumosinus dilatans multiplex”
  • 177. V3[MN] & MMA & ET in lateral & Anterior skull base – see the relationship of ET tube which is medial to V3 & MMA
  • 179. Posterior boarder of Lateral pterygoid bone leads to Foramen Ovale [ FO ] – Dr.Kuriakose
  • 180. Posterior boarder of Lateral Pterygoid bone leads to Foramen Ovale [ FO ] – Dr.Kuriakose
  • 181. Endoscopically [ Anterior skull base ] if we follow upper end of LPT posteriorly we can reach V3 [ Posterior boarder of Lateral Pterygoid bone leads to Foramen Ovale – Dr.Kuriakose ]
  • 182. In Infratemporal fossa approach- Posterior boarder of Lateral pterygoid bone leads to Foramen Ovale [ FO ] – Dr.Kuriakose
  • 183. V3 is anterior (infront) to Horizontal carotid (= Petrous carotid ) & ET – It cause indentation on the ET also .
  • 184. In open approaches in maxillary swing approach as long as you stay lateral to ET you will not injure the horizontal part of carotid
  • 185. Petrous carotid & paraclival carotid is SADDLE shape – LEG of the rider is V3
  • 186. V 3 is anteriror to all the 3 structures - Petrous carotid & ET & Parapharyngeal carotid [ very imp ]
  • 187. Cochlea in anterior skull base b is cochlea in middle cranial fossa – cochlear angle between GSPN & IAC
  • 188. V3 is an important landmark to locate the post-styloid compartment, as it is anterior to this space (Falcon et al. 2011 ) .
  • 193. See the relationship of MPP & TP which is just posterior
  • 196. Sinus of Morgagni - In nasopharyngeal carcinoma, the tumor may extend laterally and involve this sinus involving the Mandibular nerve. This produces a triad of symptoms known as Trotter's triad [ 1) Conductive deafness ( due to eustachian tube involvement) 2) Ipsilateral immobility of soft palate 3) Neuralgic pain in the distribution of V3 ]
  • 198. See the relationship between LPP & V3 which is just posterior
  • 201. ET is just posterior to MPP [ Lateral part of Posterior choanae is MPP ]
  • 202. ET is just posterior to MPP
  • 203. ET is pointing like an ARROW the posterior genu of internal carotid [ ICAp & CF is parapharyngeal carotid ]
  • 204. Sinus of Morgagni - In nasopharyngeal carcinoma, the tumor may extend laterally and involve this sinus involving the Mandibular nerve. This produces a triad of symptoms known as Trotter's triad [ 1) Conductive deafness ( due to eustachian tube involvement) 2) Ipsilateral immobility of soft palate 3) Neuralgic pain in the distribution of V3 ]
  • 207. black asterisks medial corridor to ICAp – TVPM attached to anterior surface of ET – so if we go inbetween MPM & TVPM we reach to ICAp
  • 209. Bony-cartilagenous junction of ET tube is at posterior genu of carotid - ET is pointing like an ARROW the posterior genu of internal carotid
  • 210. Yellow arrow - Bony-cartilagenous junction of ET tube is at posterior genu of carotid - ET is pointing like an ARROW the posterior genu of internal carotid
  • 211. V 3 is anteriror to all the 3 structures - Petrous carotid & ET & Parapharyngeal carotid [ very imp ]
  • 213. ET tube in SPF [Spheno-petrosal fissure]
  • 214. At bony-cartilagenous junction of ET tube – Horizonal carotid & Parapharyngeal carotid is above & below ET - My understanding
  • 215. In open approaches in maxillary swing approach as long as you stay lateral to ET you will not injure the horizontal part of carotid
  • 216. Fossa of Rossenmuller apex is laceral carotid [ Foramen Lacerum ] pharyngeal recess (fossa of Rosenmüller), which projects laterally from the posterolateral corner of the nasopharynx with its lateral apex facing the internal carotid artery laterally and the foramen lacerum above;
  • 217. endonasal approaches to expose the area between the ICAs belong to the sagittal plane, and the approaches around the ICA define the coronal plane modules.
  • 218. Note that the eustachian tube indicates the carotid canal only approximately. In other words, it lies on a different CORONAL plane in respect of the vessel, and from an anterior viewpoint, it covers the vessel for all its length. -- Medially the space between these two CORONAL planes is nothing but Fossa of Rosenmuller [ My understanding ]
  • 219. Note that the eustachian tube indicates the carotid canal only approximately. In other words, it lies on a different CORONAL plane in respect of the vessel, and from an anterior viewpoint, it covers the vessel for all its length. -- Medially the space between these two CORONAL planes is nothing but Fossa of Rosenmuller [ My understanding ]
  • 220. Surgeons should have in mind that the external orifi ce of the carotid canal is not on the same coronal plane of the foramen lacerum (anterior genu). It is by far more posteriorly located.
  • 222. SOF [ Superior Orbital Fissure ]
  • 224. Parts of SOF 1. Lateral part- LFT [ Liver functional tests ] Menumonic – Lacrimal N., Frontal N.,Trochlear N. 2.Middle part 3. Medial/Inferior part
  • 225. Parts of SOF 1. Lateral part- LFT [ Liver functional tests ] Menumonic – Lacrimal N., Frontal N.,Trochlear N. 2.Middle part 3. Medial/Inferior part
  • 227. Accessing intraconal lesions endonasally requires manipulation of the extraocular muscles. The nerve branches that supply the oculomotor muscles run in the medial surface of the muscles. Thus, try to avoid excessive retraction of the extraocular muscles to avoid inadvertent muscle paresis.
  • 228. SOF is the space between two Structs – Superiorly OS [ Optic Strut ] & Inferiorly MS [ Maxillary Strut ]
  • 229. SOF is the space between two Structs – Superiorly OS [ Optic Strut ] & Inferiorly MS [ Maxillary Strut ]
  • 230. SOF is the space between two Structs – Superiorly OS [ Optic Strut ] & Inferiorly MS [ Maxillary Strut ] Anterior view of SOF Posterior view of SOF
  • 233. Yellow line = “nasal” part of SOF Clinically, the SOF and CS apex represents a continuum.
  • 234. endoscopic endonasal viewpoint the nasal window to SOF is above V2, and below the lateral optico-carotid recess. blue-sky arrows SOF ; MS-Maxillary strut ; MP-Maxillary prominence
  • 235. Zonule of zinn - inserts on the infraoptic tubercle, which is often found as a canal located beneath the optic strut .
  • 236. The structure Infero-lateral to SOF is – Horizontal part of carotid
  • 237. Anterior to L-OCR is Superior Orbital Fissure
  • 240. MS- Maxillary strut /// Average distance from the FR at PPF and the vertical segment of ICAc is 35 mm [ 3.5cm ] (Amin et al. 2010 ) .
  • 241. SOF , Middle Fossa , V3 in line vertically
  • 243. GSPN passes above Horizontal [=petrous] carotid & passes underneath V3 & crosses petro-paraclival carotid junction at foramen lacerum before becoming vidian nerve
  • 244. The bone overlying the internal auditory canal has been removed and the dura of the canal has been removed near the fundus. The facial nerve (FN) can be seen entering its labyrinthine segment to form the geniculate ganglion (GG) more laterally. V Trigeminal nerve, < Acousticofacial bundle, C Cochlea, ET Eustachian tube, GPN Greater petrosal nerve, I Incus, IAC Internal auditory canal, ICA Internal carotid artery, M Malleus, SSC Superior semicircular canal, SV Superior vestibular nerve Observe the relationship between GSPN & horizontal carotid
  • 245. Fig. 2.62 The course of the horizontal segment of the internal carotid artery (ICAh), as seen from the middle cranial fossa of a left temporal bone. VI Abducent nerve, C Cochlea, GPN Greater petrosal nerve, IAC Internal auditory canal, ICA(ic) Intracranial internal carotid, M Mandibular nerve, MMA Middle meningeal artery, MX Maxillary nerve
  • 246. Fig. 5.47 The view after completion of the middle crannial fossa approach. AE Arcuate eminence, BB Bill’s bar, C Cochlea, FN(iac) Internal auditory canal segment of the facial nerve, FN(t) Tympanic segment of the facial nerve, G Geniculate ganglion, GPN Greater petrosal nerve, I Body of the incus, L Labyrinthine segment of the facial nerve, M Head of the malleus, MFD Middle fossa dura, SVN Superior vestibular nerve
  • 247. In Infratemporal fossa - Note that the greater petrosal nerve (GPN) is adherent to the dura, and that retracting the dura will lead to stress on the facial nerve at the geniculate ganglion (GG) level. Thus, if dural retraction is needed, cutting the petrosal nerve will prevent this injury. In middle cranial fossa – same point
  • 248. Foramen lacerum AFL = Anterior foramen lacerum * [ black asterisk ] = foramen lacerum Petrolingual area = foramen lacerum
  • 249. After elevating V3 anterior[infront] to ET & petrous carotid observe -- GSPN continues as VN [ VN is lateral to paraclival carotid ]
  • 250. GSPN & GSPN groove in Surpra petrous window ET eustachian tube, GPN greater petrosal nerve, MCFd dura of the middle cranial fossa, MMA middle meningeal artery, SPS superior petrosal surface, TI trigeminal impression, V3 third branch of the trigeminal nerve, yellow arrow accessory middle meningeal artery, white asterisks greater petrosal nerve groove
  • 251. Vidian nerve is formed by GSPN & Deep petrosal nerve – so GSPN (passes underneath V3) crosses laterally the Horizontal carotid and paraclival carotid junction (Prof.Kassam) & continues as Vidian nerve Blue arrow – LPN & Yellow arrow – GPN
  • 252. Trans-pterygoid approch-- Vidian Artery present in 60% & enters at the junction of Horizontal carotid & paraclival carotid – it is present above the Vidian nerve so while drilling vidian canal in JNA first we have to drill inferior half and then upper half [the bone around the vidian canal is drilled along its inferior half (from 3 o’clock to 9 o’clock) until the carotid artery is identified at the lacerum segment ]
  • 253. Vidian nerve - lateral to paraclival carotid & medial to FO [ Foramen Ovale ]- actually it is GSPN
  • 254. Vidian canal & Spheno-palatine foramen are in 90 degrees
  • 256. Vidian nerve - lateral to paraclival carotid
  • 257. Vidian nerve - lateral to paraclival carotid
  • 258. Vidian nerve - lateral to paraclival carotid
  • 259. Vidian nerve - lateral to paraclival carotid Close vision of the middle cranial fossa. The gasserian ganglion has been removed
  • 260. Vidian nerve - lateral to paraclival carotid
  • 261. Axial T2-weighted magnetic resonance imaging (MRI) sequence at the level of the vidian canal: 1, clivus; 2, pterygoid; 3, horizontal tract of the internal carotid artery (ICA); 4, vidian canal.
  • 262. The space between V1 & V 2 and V2 & V3 is sphenoid sinus Middle cranial fossa approach – the nerve between V2 & V3 is VN Anaterior skull base
  • 263. Infratemporal fossa approach type C Middle cranial fossa approach – the nerve between V2 & V3 is VN
  • 264. Foramen lacerum AFL = Anterior foramen lacerum * [ black asterisk ] = foramen lacerum Petrolingual area = foramen lacerum
  • 265. Vidian artery – origin from Laceral segment
  • 266. Lateral Recess is the space between V2 & Vidian nerve .
  • 267. Courtesy – Dr. Satish Jain , Jaipur
  • 268. Lateral Recess is the space between V2 & Vidian nerve .
  • 269. Here TI [ trigeminal impression ] is V2
  • 270. LRSS = Lateral recess of the sphenoid sinus
  • 273. Floor of Lateral recess is by ET ---- BS basisphenoid, ET eustachian tube, LRSS lateral recess of the sphenoid sinus, OPPB orbital process of the palatine bone, PVA(s) palatovaginal artery(ies), RPm rhinopharyngeal mucosa, SPAib inferior branch of the sphenopalatine artery, SPPB sphenoidal process of the palatine bone, SS sphenoid sinus, RS rostrum sphenoidale, VN vidian nerve
  • 275. Surpra petrous window ET eustachian tube, GPN greater petrosal nerve, MCFd dura of the middle cranial fossa, MMA middle meningeal artery, SPS superior petrosal surface, TI trigeminal impression, V3 third branch of the trigeminal nerve, yellow arrow accessory middle meningeal artery, white asterisks greater petrosal nerve groove
  • 278. Middle cranial fossa approach
  • 279. The middle fossa retractor is fixed at the petrous ridge (PR). AE Arcuate eminence, GPN Greater petrosal nerve, M Middle meningeal artery The expected location of the internal auditory canal (IAC). The bar-shaded areas are the locations for drilling. A Anterior, AE Arcuate eminence, GPN Greater petrosal nerve, MMA Middle meningeal artery, P Posterior
  • 282. Petrous apex - Quadrangular area
  • 283. Petrous apex – Triangular area
  • 286. http://www.slideshare.net/INUB/endoscopic-anatomy-and-approaches-of-the-cavernous-sinus- cadaver-study - Endoscopic view of the right cavernous sinus and neurovascular relations, demonstrating the ‘S’ shaped configuration formed by the oculomotor, the abducens and the vidian nerves. III oculomotor nerve, V1 ophthalmic nerve, V2 maxillary nerve, V3 mandibular nerve, VI abducens nerve, C clivus, ICA-Sa anterior bend of the internal carotid artery–parasellar segment, ICA-Sp posterior bend of the internal carotid artery–parasellar segment, ICA-C paraclival segment of the internal carotid artery, ICA-L lacerum segment of the internal carotid artery, ICA-P petrous segment of the internal carotid artery, PG pituitary gland, VC vidian canal, VN vidian nerve 6th nerve is parallel to V1 – in the same direction of V1
  • 287. 6th nerve is parallel to V1 – in the same direction of V1
  • 289. http://www.slideshare.net/INUB/endoscopic-anatomy-and-approaches-of-the- cavernous-sinus-cadaver-study- Endoscopic view of the right cavernous sinus and its neurovascular relations, demonstrating the triangular area formed by the medial pterygoid process laterally, the parasellar ICA medially and the vidian nerve inferiorly at the base. III oculomotor nerve, V1 ophthalmic nerve, V2 maxillary nerve, V3 mandibular nerve, VI abducens nerve, C clivus, ICA-Sa anterior bend of the internal carotid artery–parasellar segment, ICA-Sp posterior bend of the internal carotid artery–parasellar segment, ICA-C paraclival segment of the internal carotid artery, ICA- L lacerum segment of the internal carotid artery, ICA-P petrous segment of the internal carotid artery, PG pituitary gland, VC vidian canal, VN vidian nerve
  • 290. 1.Supra Trochanteric & Infratrochanteric Triangles 2. Upper & lower dural rings
  • 291. http://www.slideshare.net/INUB/endoscopic-anatomy-and-approaches-of-the-cavernous- sinus-cadaver-study -Endoscopic view of the right cavernous sinus showing its neurovascular relations and the main anatomic areas. III oculomotor nerve, V1 ophthalmic nerve, V2 maxillary nerve, V3 mandibular nerve, VI abducens nerve, C clivus, ICA-Sa anterior bend of the internal carotid artery–parasellar segment, ICA Sp posterior bend of the internal carotid artery–parasellar segment, ICA-C paraclival segment of the internal carotid artery, ICA-L lacerum segment of the internal carotid artery, ICA-P petrous segment of the internal carotid artery, PG pituitary gland, VC vidian canal, VN vidian nerve, STA superior triangular area, SQA superior quadrangular area, IQA inferior quadrangular area 1.Supra Trochanteric & Infratrochanteric Triangles 2. Upper & lower dural rings
  • 292. http://www.slideshare.net/INUB/endoscopic-anatomy-and-approaches-of-the- cavernous-sinus-cadaver-study - Endoscopic view (a), and a drawing (b) of the right cavernous sinus demonstrating its neurovascular relations. c A drawing of the right cavernous sinus demonstrating the exposure of the trochlear nerve after retracting the oculomotor nerve. III oculomotor nerve, IV trochlear nerve, V1 ophthalmic nerve, VI abducens nerve, ICA internal carotid artery, OA ophthalmic artery, OCh optic chiasm, ON optic nerve, PG pituitary gland
  • 293. Triangles of Middle cranial fossa – see Ant. Medial & Ant. Lateral triangles in both photos. http://www.eneurosurgery.com/surgicaltrianglesofthecavernoussinus.html Postero-medial Triangle = KAWASE triangle [Prof.KAWASE , JAPAN Neurosurgeon -below photo]
  • 294. Fig. 22.31 Clinoidal and oculomotor triangles have been opened and the anterior clinoid removed up to the optic strut, exposing the carotido- oculomotor membrane. The optic strut has two neural-facing surfaces( yellow dotted lines) and one vascular-facing surface (red dotted line). CN: cranial nerve; Falc.: falciform; ICA: internal carotid artery; Inf.:inferior; Lig.: ligament; Pet.: petrosal; V1: first division; V2: second division; V3: third division of trigeminal nerve. ACP anterior clinoid process, APCF anterior petroclinoid fold, DS dorsum sellae, ICF interclinoid fold, PF pituitary fossa, PLL petrolingual ligament (inferior sphenopetrosal ligament), PPCF posterior petroclinoid fold, PS planum sphenoidale, SSPL superior sphenopetrosal ligament (Gruber’s ligament), TS tuberculum sellae, black asterisk middle clinoid process
  • 296. Opticocarotid traiangle by Pterional approach
  • 299. KISSING CAROTIDS 1. http://radiopaedia.org/articles/kissing-carotids 2. http://www.ncbi.nlm.nih.gov/pubmed/17607445 • The term kissing carotids refers to tortuous and elongated vessels which touch in the midline. They can be be found in: • retropharynx 2 • intra-sphenoid 1 – within the pituitary fossa – within sphenoid sinuses – within sphenoid bones • The significance of kissing carotids is two-fold: – may mimic intra-sellar pathology – catastrophic if unknown or unreported before transsphenoidal / retropharyngeal surgery
  • 300. Cervical kissing carotids – here also papaphayrngela kinking present http://www.radrounds.com/photo/cervical-kissing- carotids-1 Coronal MIP of aberrant medial course of the carotids arteries showing the internal carotids arteries nearly touching at the C2 level.
  • 301. An Aberrant Cervical Internal Carotid Artery in the Mouth http://amjmed.org/an-aberrant-internal-carotid-artery-in-the-mouth/
  • 302. Intrasellar kissing carotid arteries -This anomaly is particularly important since it may cause or mimic pituitary disease and also may complicate transsphenoidal surgery.http://www.scielo.br/scielo.php?script=sci_arttext&pid=S0004- 282X2007000200034&lng=en&nrm=iso&tlng=en
  • 304. Looping / Kinking of Parapharyngeal carotid
  • 305. kinking or looping of the ICAp - when looping present para-pharyngeal carotid comes to pre-styloid compartment – previously thought that para-pharyngeal carotid never comes anterior to styloid mucles – which is UNTRUE
  • 307. The stylopharyngeus and styloglossus muscles are critical landmarks, being usually placed anterior to the great vessels (Dallan et al. 2011 ). Note that the presence of kinking or looping of the ICAp could make this statement untrue.
  • 308. Cervical kissing carotids – here also papaphayrngela kinking present http://www.radrounds.com/photo/cervical-kissing- carotids-1 Coronal MIP of aberrant medial course of the carotids arteries showing the internal carotids arteries nearly touching at the C2 level.
  • 309. An Aberrant Cervical Internal Carotid Artery in the Mouth http://amjmed.org/an-aberrant-internal-carotid-artery-in-the-mouth/
  • 311. In this kinking of ICA also Prof.Mario Sanna uses very flexible ICA stents
  • 312. Relation of Eustachian tube & looping of parapharyngeal carotid & styloid process
  • 317. The external carotid artery passes deeply to the digastric and stylohyoid muscles, but superficially to the stylopharyngeus and styloglossal muscle when running toward the parotid gland (Janfaza et al. 2001 ) .
  • 318. Intratemporal carotid = Horizontal carotid[= Petrous carotid] + Vertical carotid
  • 324. Endoscopic view of the eustachian tube orifice (arrow).- Note Internal carotid artery
  • 326. In Infra-temporal fossa approach The full course of the intratemporal internal carotid artery has been freed. AFL Anterior foramen lacerum, CF Carotid foramen, CL Dura overlying the clivus area, ICA(h) Horizontal segment of the internal carotid artery, ICA(v) Vertical segment of the internal carotid artery, MN Stump of the mandibular nerve Drilling of the clivus has been completed. C Basal turn of the cochlea (promontory), FN(m) Mastoid segment of the facial nerve, FN(t) Tympanic segment of the facial nerve, GG Geniculate ganglion, GPN Greater petrosal nerve, ICA Internal carotid artery, RW Round window
  • 327. Pterygoid trigone – just anterior to foramen lacerum in both photos is Pterygoid trigone
  • 329. Note the Cochlea basal turn anterior wall in left photo
  • 330. Note that the basal turn of the cochlea (BT) starts to curve superiorly near the internal carotid artery (ICA), a short distance from the level of the round window.
  • 331. In most cases, the medial aspect of the horizontal portion of the internal carotid artery is not covered by bone, but simply by dura.
  • 332. GSPN bisects the Petrous carotid & V3 and Vertical part of Facial nerve bisects Jugular bulb
  • 333. In most cases, the medial aspect of the horizontal portion of the internal carotid artery is not covered by bone, but simply by dura.
  • 334. Post-operative vasospasm of laceral segment [ carotid mobilization done for tumor removal ]
  • 336. TG ( Trigeminal ganglion ) is lateral to Paraclival carotid
  • 337. Infrapetrous Approach Carotid-Clival window – Mid clivus a. Petrosal face b.Clival face
  • 338. After drilling the carotid canal what we see is endosteal layer , not directly the ICA – Dr.Janakiram Subperiosteal/Subadventitial Dissection Subperiosteal/subadventitial dissection is accomplished for tumors that involve the ICA to a greater extent, such as C2 glomus tumors and meningiomas (Fig. 15.24a, b). In general, dissection of the tumor from the artery is relatively easier and safer in the vertical intrapetrous segment, which is thicker and more accessible than the horizontal intrapetrous segment. A plane of cleavage between the tumor and the artery should be found first. In most cases, the tumor is attached to the periosteum surrounding the artery. Dissection is better started at an area immediately free of tumor. Aggressive tumors may, however, extend even to the adventitia of the artery and subadventitial dissection may be needed. This should be done very carefully in order to avoid any tear to the arterial wall, which can become weakened (Fig. 15.25), with the risk of subsequent blowout.
  • 339. Fig. 15.25 A case of left glomus jugulare tumor in our early experience. Subadventitial dissection has been performed because the artery had been so weakened after the tumor removal. Although the patient had no relevant complications postoperatively, such excessive manipulation is better avoided and permanent balloon occlusion or stenting are preferably tried preoperatively.
  • 340. Meckels cave - Trigeminal notch at petrous apex
  • 342. Petrolingual ligament [ PLL ] & Foramen Lacerum [ FL ]
  • 345. Lingula of sphenoid red asterisk = lingula of the sphenoid black arrowhead = lingula of the sphenoid
  • 346. PLL- Petrolingual ligament - considered as a continuation of the periostium of the carotid canal (Osawa et al. 2008 ) .
  • 347. Infrapetrous Approach Carotid-Clival window – Mid clivus a. Petrosal face b.Clival face
  • 349. “Front door” to Meckel’s cave PLL - It can be considered the border between the horizontal and cavernous portions of the internal carotid artery.
  • 350. Nerves in lateral wall of cavernous in JNA case
  • 351. Foramen lacerum - The petrous ICA then curves upward above the foramen lacerum (FL), thus giving the anterior genu. The segment above the FL is not truly intrapetrous, and it has been called the lacerum segment by some authors (Bouthillier et al. 1996 ) . These segments, the anterior genu and the anterior vertical segment, are placed above the FL, and the artery does not cross the foramen. In this sense, it is better called the supralacerum segment (Herzallah and Casiano 2007 ) . Anatomically, the FL is an opening in the dry skull that in life is fi lled by fi brocartilagineous tissue (fi brocartilago basalis). AFL = Anterior foramen lacerum * [ black asterisk ] = foramen lacerum Petrolingual area = foramen lacerum
  • 352. Vidian artery – origin from Laceral segment
  • 353. 1. The foramen lacerum (FL) is located lateral to the floor of the sphenoid sinus at the level of the spheno-petro-clival confuence. 2. In respect to the FL, the JT is postero-medially located. Therefore to access the jugular tubercle from anteriorly a complete exposure of the foramen lacerum is needed. black asterisk foramen lacerum , JT jugular tubercle, HC hypoglossal canal
  • 354. PLL = INFERIOR SPHENOPETROSAL LIGAMENT ACP anterior clinoid process, APCF anterior petroclinoid fold, DS dorsum sellae, ICF interclinoid fold, PF pituitary fossa, PLL petrolingual ligament (inferior sphenopetrosal ligament), PPCF posterior petroclinoid fold, PS planum sphenoidale, SSPL superior sphenopetrosal ligament (Gruber’s ligament), TS tuberculum sellae, black asterisk middle clinoid process
  • 356. Parasellar carotid – shrimp shaped It covers four segments of the ICA: (1) the hidden segment; (2) the inferior horizontal segment; (3) the anterior vertical segment, and (4) the superior horizontal segment. The hidden segment is located at the level of the posterior sellar floor and includes the posterior bend of the ICA. The inferior horizontal segment appears short due to the perspective view, but is the longest segment of the intracavernous ICA. It courses along the sellar floor. The anterior vertical segment corresponds to the convexity of the C- shaped parasellar protuberance. The superior horizontal segment includes the clinoidal segment which courses medially to the optic strut, is anchored by the proximal and distal dural ring and continues in the subarachnoid portion of the vessel.
  • 357. Retro, Infra, Presellar prominences
  • 358. A) Cadaveric dissection image taken within the sphenoid sinus, with removal of bone over the lateral sphenoid wall. The paraclival carotid artery (PCA) enters the base of the sphenoid sinus and runs in a vertical direction. At approximately the level of the V2 (maxillary division of trigeminal nerve) the carotid artery then enters the cavernous sinus and becomes the intracavernous carotid artery (CCA). Once the artery enters the cavernous sinus it continues to ascend for a short distance, called the vertical portion of the CCA (V. CCA), before turning anteriorly at the posterior genu of the CCA (P. Genu CCA). This posterior genu corresponds to the floor of the sella. The artery then runs horizontally as the horizontal portion of the CCA (H. CCA), before reaching the anterior
  • 365. http://www.slideshare.net/INUB/endoscopic-anatomy-and-approaches-of-the- cavernous-sinus-cadaver-study- Endoscopic view of the right cavernous sinus and its neurovascular relations, demonstrating the triangular area formed by the medial pterygoid process laterally, the parasellar ICA medially and the vidian nerve inferiorly at the base. III oculomotor nerve, V1 ophthalmic nerve, V2 maxillary nerve, V3 mandibular nerve, VI abducens nerve, C clivus, ICA-Sa anterior bend of the internal carotid artery–parasellar segment, ICA-Sp posterior bend of the internal carotid artery–parasellar segment, ICA-C paraclival segment of the internal carotid artery, ICA- L lacerum segment of the internal carotid artery, ICA-P petrous segment of the internal carotid artery, PG pituitary gland, VC vidian canal, VN vidian nerve
  • 368. Branches of cavernous carotid 1. Meningohypophyseal trunk 2. Inferolateral trunk The anterior lobe of the pituitary gland is mainly fed by the superior hypophyseal arteries while the posterior lobe is fed mainly by the inferior hypophyseal artery. Branches of Intracranial carotid 1. Superior hypophyseal Artery
  • 370. The anterior lobe of the pituitary gland is mainly fed by the superior hypophyseal arteries while the posterior lobe is fed mainly by the inferior hypophyseal artery.
  • 371. Superior Hypophyseal Arteries [ SHAs ] - more commonly arise from the paraclinoid ICA - In rare cases SHAs originate from the intracavernous segment of the ICA
  • 374. The MHT is traditionally described as having three branches: 1. the inferior hypophyseal artery, IHA 2. the dorsal meningeal artery (also called the dorsal clival artery) DMA, and 3. the tentorial artery (also called the Bernasconi-Cassinari artery) BCA .
  • 376. At superior part of Siphon carotid , SHA arises where as inferior part of Siphon carotid MHT [ Inferior hypophyseal artery ] arises
  • 377. DMA main feeder of dorellos segement of 6th nerve DMA main feeder of dorellos segement of 6th nerve
  • 380. In most cases ILT passes superiorly to the abducens nerve (Inoue et al. 1990 ; Jittapiromsak et al. 2010 ) .
  • 381. In most cases ILT passes superiorly to the abducens nerve (Inoue et al. 1990 ; Jittapiromsak et al. 2010 ) .
  • 385. ICA Clin.: clinoid, clinoidal
  • 386. Dural rings – the ICA between upper & lower dural ring is Clinoidal ICA
  • 387. Cl clivus, ICAc cavernous portion of the internal carotid artery, ON optic nerve, PG pituitary gland, PS planum sphenoidale, TS tuberculum sellae, yellow asterisks upper dural ring, blue arrowheads lower dural ring, white asterisk lateral optico-carotid recess, white circle medial optico-carotid recess, white arrow ophthalmic artery, black arrows middle clinoid process, red arrows lateral tubercular crest, yellow arrows endocranial region corresponding to MCP
  • 388. Lower dural ring is nothing but COM [ Carotico-occulomotor membrane ] - The dura lining the inferior aspect of the anterior clinoid process forms the lower dural ring. This ring is often incomplete on the medial side and often a venous channel can follow the paraclinoidal ICA to the upper dural ring. By Fronto temporal approach
  • 389. lower dural ring - This ring is often incomplete on the medial side and often a venous channel can follow the paraclinoidal ICA to the upper dural ring.
  • 390. blue-sky arrow = upper dural ring,
  • 391. The lower dural ring is given by the COM [ Carotid-oculomotor membrane ] , that lines the inferior surface of the ACP. It can be visible, through a transcranial route, only by removing the ACP. The lower dural ring is also called Perneczky’s ring. Medially the COM blends with the dura that lines the carotid sulcus (Yasuda et al. 2005 ) Endoscopic supraorbital view with a 30° down-facing lens -The right portion of the planum sphenoidale is seen from above. Right side
  • 392. Upper & lower dural rings
  • 393. 1.Supra Trochanteric & Infratrochanteric Triangles 2. Upper & lower dural rings
  • 394. ICAcl clinoidal portion of the internal carotid artery , The clinoidal segment of the internal carotid artery faces the posterior aspect of the optic strut. white arrowhead - paraclinoid portion of the internal carotid artery – after removal of anterior clinoidal process
  • 395. ICA Clin.: clinoid, clinoidal [ Observe here also – posterior border of Optico- carotid recess is Clinoidal ICA ]
  • 396. ICA Clin.: clinoid, clinoidal
  • 397. ICA Clin.: clinoid, clinoidal
  • 398. ICA Clin.: clinoid, clinoidal
  • 399. ICA Clin.: clinoid, clinoidal
  • 400. Intracranial portion of ICA [ICA i]
  • 401. The mOCR is located just medial to the paraclinoidal-supraclinoidal ICA transition and inferior to the distal cisternal segment of the ON(Labib et al. 2013 ). Cl clivus, ICAc cavernous portion of the internal carotid artery, ON optic nerve, PG pituitary gland, PS planum sphenoidale, TS tuberculum sellae, yellow asterisks upper dural ring, blue arrowheads lower dural ring, white asterisk lateral optico-carotid recess, white circle medial optico-carotid recess, white arrow ophthalmic artery, black arrows middle clinoid process, red arrows lateral tubercular crest, yellow arrows endocranial region corresponding to MCP
  • 402. Opthalmic artery – Retrograde branch of Intracranial carotid Branches of the cavernous internal carotid artery ( ICA ), a rare variation: ophthalmic artery passing through the superior orbital fissure
  • 403. In the lateral border of the chiasmatic cistern the first part of the ICAi is visible. Note Optic tract here which is above Posterior clinoid process [ PCP ]
  • 404. Supra-clinoidal carotid=1st part of intracranial carotid
  • 405. APAs anterior perforating arteries, ICAi intracranial portion of the internal carotid artery, OT optic tract, SF Sylvian fi ssure,
  • 406. ACA anterior cerebral artery, APAs anterior perforating arteries, FOA fronto-orbital artery, FOV fronto-orbital vein, FPA fronto-polar artery, ICAi intracranial segment of the internal carotid artery, MCA middle cerebral artery, OlfT olfactory tract, OlfV olfactory vein, ON optic nerve, PS pituitary stalk, TL temporal lobe, black asterisk anterior communicating artery
  • 407. ICA dividing into ACA and MCA
  • 409. Optic tract [ OT ]
  • 416. Surpra petrous window [ see the GSPN groove here ] ET eustachian tube, GPN greater petrosal nerve, MCFd dura of the middle cranial fossa, MMA middle meningeal artery, SPS superior petrosal surface, TI trigeminal impression, V3 third branch of the trigeminal nerve, yellow arrow accessory middle meningeal artery, white asterisks greater petrosal nerve groove
  • 418. Inferior petrosal sinus is superior to jugular tubercle & hypoglossal canal is inferior to jugular tubercle Infratemporal fossa [=intact cochlear approach – Dr.Morwani ] type B approach
  • 419. The pontomedullary junction. 1. The exit zones of the hypoglossal and abducent nerves are at the same level [ same vertical line when view from Transclival approah ( through lower clivus ) ] 2. The abducent nerve exits from the pontomedullary junction, and ascends in a rostral and lateral direction toward the clivus.
  • 421. In infrapetrous approach there are chances of injury to 6th nerve [ in dorello’s canal medial to paraclival carotid ] & 12th nerve
  • 422. When we are drilling lower clivus – lateral to hypoglossal canal we get Jugular fossa
  • 423. Adenoid cycstic carcinoma clivus -- Just look at the carotid. .The paraclival both sides 360 degree encased..look at the mass eroding Petros apex going above horizontal carotid above the meckels cave..we need a trans cavernous..trans supra Petros. .infra Petros. . App..
  • 425. Fig. 2.1 Drawing showing the skin incision (red line), the craniotomy and the microsurgical intraoperative view of the subfrontal unilateral approach. This approach provides a wide intracranial exposure of the frontal lobe and easy access to the optic nerves, the chiasm, the carotid arteries and the anterior communicating complex
  • 426. Fig. 2.4 Intraoperative microsurgical photograph showing contralateral extension of the tumor (T) dissected via a unilateral subfrontal approach. Note on the left side the falx cerebri (F) and the mesial surface of the left frontal lobe (FL)
  • 427. Fig. 2.5 Drawing showing the skin incision (red line), the craniotomy and the microsurgical anatomic view of the subfrontal bilateral route. This approach provides a wide symmetrical anterior cranial fossa exposure and easy access to the optic nerves, the chiasm, the carotid arteries and the anterior communicating arteries complex
  • 428. Supraorbital approach - Fig. 3.2 Illustrations comparing the incision and bony exposure in a supraorbital craniotomy with those in a pterional craniotomy. a The supraorbital craniotomy utilizes the subfrontal corridor and involves a frontobasal burr hole and removal of a small window in the frontal bone. b The pterional craniotomy utilizes a frontotemporal incision and removal of the frontal and temporal bones andsphenoid wing. The pterional craniotomy primarily exploits the sylvian fissure
  • 430. Fig. 4.6 a Craniotomy. b When the flap has been removed the lesser wing of the sphenoid is drilled down to optimize the most basal trajectory to the skull base. c Dural opening. DM dura mater, FL frontal lobe, MMA middle meningeal artery, LWSB lesser wing of the sphenoid bone, SF sylvian fissure, TL temporal lobe, TM temporal muscle, ZPFB zygomatic process of the frontal bone
  • 431. Fig. 4.8 Intradural exposure; right approach. Before (a) and after (b) opening of the Sylvian fissure. A1 first segment of the anterior cerebral artery, AC anterior clinoid, FL frontal lobe, HA Heubner’s artery, I olfactory tract, III oculomotor nerve, ICA internal carotid artery, LT lamina terminalis, M1 first segment of the middle cerebral artery, MPAs perforating arteries, ON optic nerve, P2 second segment of the posterior cerebral artery, PC posterior clinoid, PcoA posterior communicating artery, SF sylvian fissure, TL temporal lobe, TS tuberculum sellae
  • 432. Fig. 4.9 Intradural exposure; right approach. a Instruments enlarging the optocarotid area. b Displacing medially the posterior communicating artery, exposing the contents of the interpeduncular cistern. AC anterior clinoid, AchA anterior choroidal artery, BA basilar artery, FL frontal lobe, ICA internal carotid artery, III oculomotor nerve, OA left ophthalmic artery, ON optic nerve, OT optic tract, P2 second segment of the posterior cerebral artery, PC posterior clinoid, PcoA posterior communicating artery, Ps pituitary stalk, SCA superior cerebellar artery, SHA superior hypophyseal artery, TE tentorial edge, TL temporal lobe
  • 433. Fig. 4.10 Intradural exposure; right approach; enlarged view. A1 first segment of the anterior cerebral artery, A2 second segment of the anterior cerebral artery, AC anterior clinoid, AcoA anterior communicating artery, BA basilar artery, FL frontal lobe, HA Heubner’s artery, ICA internal carotid artery, III oculomotor nerve, LT lamina terminalis, M1 first segment of the middle cerebral artery, OA left ophthalmic artery, ON optic nerve, P2 second segment of the posterior cerebral artery, PC posterior clinoid, PcoA posterior communicating artery, SCA superior cerebellar artery, SHA superior hypophyseal artery, TE tentorial edge, TL temporal lobe, TS tuberculum sellae
  • 434. Fig. 4.11 Intradural exposure; right approach; close-up view ofthe interpeduncular fossa. AchA anterior choroidal artery, BAbasilar artery, DS dorsum sellae, III oculomotor nerve, IV trochlear nerve, P1 first segment of the posterior cerebral artery,P2 second segment of the posterior cerebral artery, PC posteriorclinoid, PcoA posterior communicating artery, Ps pituitary stalk, SCA superior cerebellar artery, TE tentorial edge
  • 435. Endoscope-assisted microsurgery [ 45° endoscope in a corridor between the carotid artery and the oculomotor nerve ]-- Fig. 4.12 Intradural exposure; right approach; microsurgical (a) and endoscopic (b–d) views. AchA anterior choroidal artery, BA basilar artery, C clivus, FL frontal lobe, ICA internal carotid artery, III oculomotor nerve, ON optic nerve, P1 first segment of the posterior cerebral artery, P2 second segment of the posterior cerebral artery, PC posterior clinoid, PCA posterior cerebral artery, PcoA posterior communicating artery, SCA superior cerebellar artery, TE tentorial edge, TL temporal lobe, Tu thalamoperforating artery; green dotted triangle area for entry of the endoscope into the interpeduncular fossa
  • 436. Fig. 4.12 Intradural exposure; right approach; microsurgical (a) and endoscopic (b–d) views. AchA anterior choroidal artery, BA basilar artery, C clivus, FL frontal lobe, ICA internal carotid artery, III oculomotor nerve, ON optic nerve, P1 first segment of the posterior cerebral artery, P2 second segment of the posterior cerebral artery, PC posterior clinoid, PCA posterior cerebral artery, PcoA posterior communicating artery, SCA superior cerebellar artery, TE tentorial edge, TL temporal lobe, Tu thalamoperforating artery; green dotted triangle area for entry of the endoscope into the interpeduncular fossa
  • 437. Fig. 4.13 Intradural exposure; right approach; microsurgical (a) and endoscopic omolateral (b) and contralateral (c) views. A1 first segment of the anterior cerebral artery, AC anterior clinoid, ICA internal carotid artery, FL frontal lobe, III oculomotor nerve, LT lamina terminalis, M1 first segment of the middle cerebral artery, OA left ophthalmic artery, ON optic nerve, PcoA posterior communicating artery, SHA superior hypophyseal artery, TE tentorial edge, TS tuberculum sellae
  • 438. Fig. 4.13 Intradural exposure; right approach; microsurgical (a) and endoscopic omolateral (b) and contralateral (c) views. A1 first segment of the anterior cerebral artery, AC anterior clinoid, ICA internal carotid artery, FL frontal lobe, III oculomotor nerve, LT lamina terminalis, M1 first segment of the middle cerebral artery, OA left ophthalmic artery, ON optic nerve, PcoA posterior communicating artery, SHA superior hypophyseal artery, TE tentorial edge, TS tuberculum sellae
  • 439. Fronto-temporal orbitozygomatic transcavernous approach COM= Caratico-occulomotor membrane , DR = dural ring
  • 443. Fig. 4.15 Microsurgical view; extradural anterior clinoidectomy. a Exposure and drilling of the anterior clinoid process and optic canal under microscope magnification. b Widened space after complete removal of the AC. AC anterior clinoid, eON extracranial intracanalar optic nerve, FD frontal dura, ICA internal carotid artery, iON intraorbital optic nerve, LWSB lesser wing of sphenoid bone, OC optic canal, OR orbit roof, SOF superior orbital fissure, TD temporal dura
  • 444. Fig. 4.16 Microsurgical view; intradural anterior clinoidectomy. a, b After the dura above the anterior clinoid process has been transected in a “T” shape (a), we usually drill always parallel tothe optic nerve and to the carotid artery (b). c The distal ring is finally exposed. A1 precommunicating anterior cerebral artery, AC anterior clinoid, AchA anterior choroid artery, Ch optic chiasm, DR distal ring, fl falciform ligament, FL frontal lobe, ICA internal carotid artery, M1 first tract of the middle cerebral artery, ON optic nerve, PC posterior clinoid, PCOA posterior communicating artery, TS tuberculum sellae
  • 445. Fig. 4.16 Microsurgical view; intradural anterior clinoidectomy. a, b After the dura above the anterior clinoid process has been transected in a “T” shape (a), we usually drill always parallel tothe optic nerve and to the carotid artery (b). c The distal ring is finally exposed. A1 precommunicating anterior cerebral artery, AC anterior clinoid, AchA anterior choroid artery, Ch optic chiasm, DR distal ring, fl falciform ligament, FL frontal lobe, ICA internal carotid artery, M1 first tract of the middle cerebral artery, ON optic nerve, PC posterior clinoid, PCOA posterior communicating artery, TS tuberculum sellae
  • 450. Fig. 7.13 a Intraoperative photograph shows good exposure of the left tentorial anterior and middle incisura obtained through the pretemporal and subtemporal corridors. In this patient the basilar apex is well above the superior margin of the dorsum sellae. b Same patient. A more lateral exposure showing the pontomesencephalic junction surface and the neurovascular structures in the ambient cistern. c Intraoperative photograph of another patient showing structures in the left lateral incisural space from the subtemporal corridor. d Same patient. More lateral view. e Same patient. More posterior exposure. The lifting of the free edge of the tentorium shows the trochlear nerve entering the tentorium. The junction between the P2a and P2p segments (P2a, P2p) of the posterior cerebral artery is shown. ACA anterior cerebralartery, AChA anterior choroidal artery and tiny perforating vessels, BA basilar artery, DS dorsum sellae, FET free edge of tentorium, ICA internal carotid artery, LM Liliequist’s membrane, LON left optic nerve, ON oculomotor nerve, OT optic tract, PCA posterior cerebral artery, PComA posterior communicating artery, PLChA posterolateral choroidal artery arising from the P2a–P2p junction, PS pituitary stalk, RON right optic nerve, SCA superior cerebellar artery, TN trochlear nerve in the arachnoidal covering
  • 451. Fig. 7.13 a Intraoperative photograph shows good exposure of the left tentorial anterior and middle incisura obtained through the pretemporal and subtemporal corridors. In this patient the basilar apex is well above the superior margin of the dorsum sellae. b Same patient. A more lateral exposure showing the pontomesencephalic junction surface and the neurovascular structures in the ambient cistern. c Intraoperative photograph of another patient showing structures in the left lateral incisural space from the subtemporal corridor. d Same patient. More lateral view. e Same patient. More posterior exposure. The lifting of the free edge of the tentorium shows the trochlear nerve entering the tentorium. The junction between the P2a and P2p segments (P2a, P2p) of the posterior cerebral artery is shown. ACA anterior cerebral artery, AChA anterior choroidal artery and tiny perforating vessels, BA basilar artery, DS dorsum sellae, FET free edge of tentorium, ICA internal carotid artery, LM Liliequist’s membrane, LON left optic nerve, ON oculomotor nerve, OT optic tract, PCA posterior cerebral artery, PComA posterior communicating artery, PLChA posterolateral choroidal artery arising from the P2a–P2p junction, PS pituitary stalk, RON right optic nerve, SCA superior cerebellar artery, TN trochlear nerve in the arachnoidal covering
  • 452. Fig. 7.13 a Intraoperative photograph shows good exposure of the left tentorial anterior and middle incisura obtained through the pretemporal and subtemporal corridors. In this patient the basilar apex is well above the superior margin of the dorsum sellae. b Same patient. A more lateral exposure showing the pontomesencephalic junction surface and the neurovascular structures in the ambient cistern. c Intraoperative photograph of another patient showing structures in the left lateral incisural space from the subtemporal corridor. d Same patient. More lateral view. e Same patient. More posterior exposure. The lifting of the free edge of the tentorium shows the trochlear nerve entering the tentorium. The junction between the P2a and P2p segments (P2a, P2p) of the posterior cerebral artery is shown. ACA anterior cerebralartery, AChA anterior choroidal artery and tiny perforating vessels, BA basilar artery, DS dorsum sellae, FET free edge of tentorium, ICA internal carotid artery, LM Liliequist’s membrane, LON left optic nerve, ON oculomotor nerve, OT optic tract, PCA posterior cerebral artery, PComA posterior communicating artery, PLChA posterolateral choroidal artery arising from the P2a–P2p junction, PS pituitary stalk, RON right optic nerve, SCA superior cerebellar artery, TN trochlear nerve in the arachnoidal covering
  • 453. THE FULLY ENDOSCOPIC SUBTEMPORAL APPROACH [ from Shahanian book ] - The traditional middle fossa subtemporal approach requires long- standing placement of retractors on the temporal lobe; therefore, potential injury to the temporal lobe can occur (e.g., hematoma and edema resulting in aphasia, hemiparesis, or seizures). This concern should not be a problem with the described approach because temporal lobe retractors are not used. (L) a Epidermoid tumor. b Atraumatic suction. c Brainstem. d Occulomotor (III) nerve. e Posterior cerebral artery (PCA). f Superior cerebellar artery (SCA). g Trochlear (IV) nerve. (N) a Epidermoid tumor. b Atraumatic suction. c Left-curved tumor forceps. d Occulomotor (III) nerve. e Posterior cerebral artery (PCA). f Posterior communicating (PCOM) artery. g Superior cerebellar artery (SCA). h Brainstem. i Trochlear (IV) nerve.
  • 454. Q) a Occulomotor (III) nerve. b Internal carotid artery (ICA). c Posterior cerebral artery (PCA). d Superior cerebellar artery (SCA). (P) a Ipsilateral optic (II) nerve. b Internal carotid artery (ICA). c Occulomotor (III) nerve. d Dura overlying anterior clinoid process.
  • 459. SKULL BASE 360° Above presentation is SKULL BASE 360°-Part 1 For SKULL BASE 360°-Part 2 Please click or copy/paste in URL or weblink area http://www.slideshare.net/muralichandnallamoth u/edit_my_uploads [ Dated: 19-4-14 ] I will update continuosly with date tag at the end as I am getting more & more information