1. IPS 360°
24-4-2016
1.47am

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

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4. IPS & HVP hypoglossal
venous plexus
Cadaveric dissection image showing the
hypoglossal nerve exiting the hypoglossal
foramen with its corresponding vein that
communicates the internal jugular vein
with the basilar plexus

5. JT = jugular tubercle separates the hypoglossal
canal from Jugular foramen

6. The petrous portion of the temporal
bone or pyramid is pyramidal

7. the anterior petrosectomy with preoperative embolization of the inferior
petrosal sinus is a time-conserving approach giving one of the best routes to
reach the ventral brainstem while working in front of the cranial nerves and
preserving hearing.
http://www.worldneurosurgery.org/article/S0090-3019(00)00271-8/fulltext

8. The Petro-occipital Fissure- contains IPS

9. The Petro-occipital Fissure- contains
IPS

10. Exocranial & Endocranial views of Jugular Foramen : Within the JF
area 2 venous compartement can be identified: a large postero-
lateral_SIGMOID_venous channel and a small antero-medial_PETROSAL_venous
channel which can receive the drainage of the inferior petrosal sinus (IPS). An
intermediary neural compartment is located between the venous ones and houses
lower cranial nerves (IX, X, XI).
CC carotid canal, CR carotid ridge, ESF endolymphatic sac fossa, FS foramen spinosum, IAM internal acoustic
meatus, JT jugular tubercle, OC occipital condyle, PCF petroclival fi ssure, SAF subarcuate fossa, SP styloid
process, SSG sigmoid sinus groove, TB tympanic bone, VPTB vaginal process of the tympanic bone, white
arrow intrajugular process of the temporal bone, red arrow external ori fi ce of the hypoglossal canal, violet
arrow petroclival fi ssure, blue-sky arrow tubal isthmus, black arrow endocranial orifice of the hypoglossal
canal, orange arrow trigeminal impression, green arrow pyramidal fossa, black asterisks intrajugular ridge,
black circle intrajugularprocess of the occipital bone

11. Usually inferior petrosal sinus
opens into jugular bulb
Sometimes along with jugular
bulb opening , it opens into
internal jugular vein also [ lower
single arrow in below photo ]

12. Inferior petrosal sinus

13. a. IPS inferior to nerve IX and
superior to nerves X and XII.
b. IPS inferior and medial to all
four nerves.
c. IPS superior and lateral to all
four nerves
d. A second IPS joining the
internal jugular vein passing
medial to IX and lateral to X,
XI, and XII

14. An anatomical classification according to the level of the inferior
petrosal sinus–internal jugular vein junction has been developed
1. Junction at the level of the
jugular bulb
2. Junction at the level of the anterior
condylar vein junction (extracranial
opening of the hypoglossal canal)

15. 3. Junction at the level of the
lower extracranial jugular vein
• CoC - level of the condylar
canal
• IJV- internal jugular vein
• JF- level of the jugular
foramen
• SS- sigmoid sinus
• VVP- vertebral venous
plexus

16. 4. Multiple junctions: upper junction at the level of the jugular bulb and
lower junction at the level of the anterior condylar vein
a )Multiple upper junctions at the level of the jugular bulb (JB).
b )Multiple junctions: upper junctions at the level of the jugular bulb and lower
junction at the level of the anterior condylar vein.
c) No connection between the internal petrosal sinus and the internal jugular vein. The
sinus drains in the vertebral venous plexus.

18. In Transcochlear approach

19. In infratemporal fossa [=intact
cochlear approach –
Dr.Morwani ] type B
approach
See IPS in Kawase approach

20. 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

21. See IPS & SPS in below photo
A dissection from the superior aspect of the temporal bone. The horizontal portion of the
internal carotid artery (ICA) is identified and its anterior medial part is covered by the gasserian
ganglion (GsG). The greater superficial petrosal (gspn) nerve runs on the superolateral aspect of
the artery.

22. Right sided anterior petrosectomy on a cadaver dissection: intradural exposure
and operative field. PCA Petrous carotid artery; DPA drilled petrous apex; IPS
inferior petrosal sinus; BA basilar artery; VI 6th cranial nerve; AICA anterior inferior
cerebellar artery; P pons; V 5th cranial nerve

23. NOTE Inferior petrosal sinus at CLIVUS
ICAc cavernous portion of the internal carotid artery, IPS inferior petrosal sinus, PAp petrous
apex, SPCG sphenopetroclival gulf, cVIcn cisternal segment of the abducens nerve, gVIcn gulfar
segment of the abducens nerve, pVIcn petrosal segment of the abducens nerve, white asterisks
dura of the posterior cranial fossa

24. In infrapetrous approach there are chances of injury to 6th nerve [ in dorello’s
canal medial to paraclival carotid ] & 12th nerve

25. In middle cranial fossa approach

26. In middle cranial fossa approach

27. ITFA with Transcondylar
Transtubercular approach
Here Transcondylar is through Occipital Condyle ;
Transtubercular is through Jugular tubercle

28. * occipital condyle , IJV internal jugular vein , IPS inferior petrosal sinus
, JB jugular vein , PCV posterior condylar vein , SS sigmoid sinus

29. Note the relationship among the sigmoid sinus, jugular bulb, posterior condylar vein, vertebral
artery, and lower cranial nerves. C1 atlas , C2N C2 nerve , JB jugular bulb , PCV posterior
condylar vein SS sigmoid sinus , TP transverse process of C1 , VA vertebral artery , X vagus nerve
, XI spinal accessory nerve

30. The posterior condylar vein crossing the occipital condyle is noted.
ICA internal carotid artery , JB jugular bulb , PCV posterior condylar vein
IX glossopharyngeal nerve , XI spinal accessory nerve

31. After removal of the posterior condylar vein and further removal of the occipital condyle (OC),
the hypoglossal nerve (XII) is noted. , ICA internal carotid artery , JB jugular bulb
JT jugular tubercle , OC occipital condyle , VA vertebral artery , XI spinal accessory nerve , XII
hypoglossal nerve

32. The lower cranial nerves have an intimate relationship with the jugular tubercle (three black
arrows). When the occipital bone and jugular tubercle are being drilled, careful attention should be paid
to avoiding damage to the lower cranial nerves. , Cbl cerebellum , ICA internal carotid artery , OC occipital
condyle , TP transverse process of the C1 vertebra , VA vertebral artery , VIII cochleovestibular nerve , IX
glossopharyngeal nerve , XI spinal accessory nerve

33. For Other powerpoint presentatioins
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“ Skull base 360° ”
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