MUCOSAL FOLD OF THE MIDDLE EAR BY DR SMRUTI RANJAN SAMAL

1. Mucosal Folds of the Middle
Ear
Dr . Smruti Ranjan Samal
First Year P.G.
Department of E.N.T.,VIMSAR

2. Mucosal Fold Development
 Between 3rd to 7th month of fetal age , the
mesenchymal tissue of middle ear cleft is
absorbed.
 Simultaneously the primitive tympanic cavity
develops by a growth of an endothelium-lined
fluid pouch(Tubo Tympanic Recess) extending
from the ET into the cleft.
 The terminal end of the TTR buds out to form
4 primary sacci- saccus anticus,saccus
medius, saccus superior and saccus posticus
 The sacci or pouches start to enlarge in the
middle ear cleft to replace the pre-existing
mesenchyme.

3.  Walls of the pouches mucosal lining of middle
ear
 Mucosal fold  Plane of contact between two
neighbouring pouches.

5.  Mucosal folds extend from the wall of
middle ear to its content & carry ligaments
and blood vessels to the ossicles.
 These folds orient the progress of middle
ear pathologies but are not true barrier
against their extension.
 Mucosal folds- two types
a) Composite fold: ligament+ lining mucosa
ex:Ant.MLF, Lat.MLF and Post. Incudal
fold
b) Duplicate fold: fusion of two expanding
air sac walls in absence of any
interposing structure. ex: tensor tympani
fold, lateral incudomalleal fold.

6.  Important folds in middle ear:
1. Anterior malleal fold
2. Posterior malleal fold
3. Anterior malleal ligamental fold
4. Lateral malleal ligamental fold
5. Superior malleal fold
6. Superior incudal fold
7. Posterior incudal fold
8. Medial incudal fold
9. Lateral incudomalleal fold
10. Tensor tympani fold

7. Anterior Malleal Fold
 Origin : anterior portion neck of
malleus
 Insertion : anteriorly on ant.
tympanic spine
 Forms: medial wall of ant. Pouch of
Von Troltsch
Posterior Malleal Fold
 Origin : posterior portion neck of
malleus
 Insertion : posteriorly on post.
tympanic spine
 Forms: medial wall of post. Pouch of
Von Troltsch

8. Anterior Malleal Ligamental Fold
 Originates from neck of
malleus & extends to the
anterior attic bony wall.
 Reflected from lateral wall
of middle ear over
- Ant. Process and ligament
of malleus
- Ant. Part of Chorda
Tympani
 Low posterior part is broad
and represents – ant. Limit
of Prussak’s space.

9. Lateral Malleal Ligamental Fold
 Originates from middle portion of
the neck of malleus & attaches to
attic outer wall
 Posteriorly confluent with ant.
Descending portion of Lat. IMF
 Mostly complete, thick fold and
strong , so prevents progression of
pars flaccida retraction
 Represents roof of Prussak’s space
and the floor of the lateral malleal
space

10. Superior Malleal Fold:
 Extends between superior surface of Malleal head
and tegmen.
 Contains Superior Malleal ligament.
 Divides upper unit of attic into anterior and posterior
parts.
Superior Incudal Fold:
 Extends between superior surface incudal body to
tegmen
 Divides posterior attic to lateral and medial part

11. Posterior Incudal Fold
Lies between the
fibres of the post.
incudal ligament
Medial Incudal Fold
Lies between the long
process of the incus
and the tendon of the
stapedial muscle upto
pyramidal eminance

12. Lateral Incudomalleal Fold
Present superiorly in relation to lateral
malleal ligamental fold
Divides upper lateral attic space from
the lower lateral attic space
It has 2 extensions:
1. Posteriorly it horizontally extends to insert
medially onto body of the incus &
incudomalleal joint.
2. Laterally , it insert onto the medial surface
of the bony wall of scutum

13.  Ant. Portion of the this fold bends inferiorly
towards the neck of malleus & merges with post.
portion of lat. MLF representing the post. limit of
Lat. Malleal space
 Level is about 1mm higher than the roof of
Prussak’s space

14. Tensor Tympanic Fold
 Part of tympanic diaphragm
 Arises posteriorly from the tensor tympani
tendon
 Anteriorly inserts into a transverse
crest(supratubal ridge) of anterior wall of
the attic
 Medially insert on the bony canal of the
TTM
 Laterally insert on anterior malleal
ligament
 Separates the anterior epitympanic
recess superiorly from the supratubal
recess inferiorly

15.  TTF results from fusion of saccus
anticus & anterior saccule of the
saccus medius
 Inclination angle of the TTF varies bet.
800 -1000 depending on the variable
growth of each saccule
 Determines the size of Supra Tubal
Recess and Anterior Epitympanic
Recess

16.  TTF complete -total separation between ant.
epitympanum and protympanum
 But in majority of population TTF is incomplete.
Resulting in direct communication between ET
to ant. Epitympanic recess and then to
posterior attic. Hence prevents attic
dysventilation.

17. Tympanic Diaphragm
formed by
- Three malleal ligamental folds
- The posterior incudal fold
- The Tensor Tympani Fold
- The lateral incudomalleal fold
- Incus and Malleus
As theses components are on different level
Tympanic Diaphragm is not fully Horizontal
 Separates the upper unit of attic superiorly
and lower unit of attic, the Prussak’s space
inferiorly from mesotympanum

18. Tympanic Isthmus
- Attic and mastoid are isolated from
mesotympanum by Tympanic Diaphragm
- Attic aeration occurs through a 2.5 mm
opening in the tympanic diaphragm 
Tympanic Isthmus
- Anteriorly - extends from tensor tympani
muscle
- Posterosuperiorly – post. Incudal ligament
- Posteroinferiorly – pyramidal eminence
- Medially – limited by attic bone
- Laterally – limited by body and short process
of incus and head of malleus

19. Tympanic isthmus divided by the medial
incudal fold into 2 portion
1. The Anterior Tympanic Isthmus
Between TTM anteriorly & the stapes posteriorly
2. The Posterior tympanic Isthmus
Between short process of incus & stapedial muscle

20. Clinical Correlation
- In long standing COM, granulation tissue and webs - block the
tympanic isthmus – failure of attic ventilation even in presence of
normal ET and well aerated mesotympanum
- This is called selective attic dysventilation
- Results in chronic attic inflammation, attic retraction pockets and
attic cholesteatoma
- Incomplete TTF allows good ventilation from the protympanic
space to anterior attic and prevents attic dysventilation even in
case of tympanic isthmus blockage
- This signifies the importance of TTF removal during surgical
treatment of middle ear disease to ensure a good ventilation of
the attic region

21. MIDDLE EAR SPACES
anterior posterior

22. THE EPITYMPANUM (ATTIC)
 Situated above the imaginary line passing through the
lateral process of malleus
 Lodges the
- head and neck of malleus
- body and short process of incus
 Boundaries
Lateral wall – shrapnell’s membrane (inf)
- scutum (sup)
Posterior wall – almost entirely by aditus
ad antrum

23. Medial wall- part of medial wall situated above
the tympanic segment of the facial nerve &
Tensor Tympani Muscle.
- it contains lateral semicircular canal
- this wall may pneumatized by
supralabrynthine tract
Posterior wall: by Aditus ad antrum
Inferiorly: Tympanic Diaphragm divides attic
into upper unit & lower unit ( Prussak”s space)

25. Upper Unit of Attic
- Above the tympanic diaphragm
- Medially – tympanic diaphragm separates upper
unit from mesotympanum almost entirely except
at tympanic isthmus
- Laterally – tympanic diaphragm separates the
upper unit of attic from lower unit (Prussak’s
space)
- Posteriorly – communicates with mastoid cavity
through aditus
- Superior Malleal fold in coronal orientation divide
- posterior attic (larger)

27. POSTERIOR ATTIC
- Contains mainly – post. part of the head of
malleus,
- body and short process of
incus
- Distance from tip of incus to attic roof is 6 mm
- Superior Incudal fold – sagittal plane. Divides into
- medial posterior (larger)
-lateral posterior attic (smaller)
Medial posterior attic
- Also called as Medial Incudal space
- Medially – lateral semicircular canal and fallopian
canal
- Laterally – ossicles and superior Incudal fold

28. Lateral Posterior Attic
- Narrower
- Laterally – outer attic wall
- Medially – malleus head, incus body, superior
Incudal fold
Divided into 3 spaces
1.Upper lateral attic –Superior Incudal
space,lateral Malleal space and 2.Lower lateral
attic – inferior Incudal space
 Superior Incudal space
- Lies in a more superior position in relation to
lateral Malleal space
- Inferiorly – incudomalleal fold (separates from
inf. Incudal space)

31. Lateral Malleal space
Lies above the lateral malleal fold
Medially: malleus head & neck
Laterally: outer attic wall
Anterior : Anterior malleal fold
Posteriorly: downward turning end of
incudomalleal fold
* Superiorly opened to superior incudal space

32. Lower Lateral Attic: Inferior Incudal Space
Lies between short process and body of Incus
medially & scutum laterally
Anterior Attic or Anterior Epitympanum
Anterior to the head of malleus and superior
Malleal fold
 Cog – bony crest that extends inferiorly from
the tegmen
- superior to cochleariform process
- anterosuperior to malleus head
Divides anterior attic into
1. posterior (small) – Anterior Malleal Space
2. anterior (large) – Anterior Epitympanic
Recess

33. Anterior Malleal Space
Variable size
Situated between head of malleus posteriorly
and cog anteriorly

34. Anterior Epitympanic Recess
Anterior epitympanic sinus/ Anterior
epitympanic space/ sinus epitympani
Superiorly – Anterior part of tegmen tympani
Anteriorly – Root of zygoma
Posteriorly – Cog
Laterally – Scutum
Medially – ant. portion of the tympanic portion
of facial nerve and geniculate ganglion
Floor - cochleariform process and tensor
tympani fold

35. AER is highly important in cases of
1. recurrent otorrhea with central or anterior
perforation not responding to medications
2. middle ear effusion that persists or recurs
despite repetitive myringotomies with tube
insertion
3. anterosuperiorly oriented retraction pocket
In these cases if the TTF is complete – blocks
aeration of anterior epitympanum from antero-
superior mesotympanum creating
dysventilation syndrome
These patients will not respond to posterior
atticotomy alone
Resection of the cog and TTF is fundamental

36. Lower unit of attic (Prussak’s space)
Formed from posterior pouch of Von Troltsch as a
prolongation of Superior Saccus
Boundaries
Roof – lateral Malleal fold
Floor – neck of malleus
Anterior – anterior Malleal fold
Laterally – pars flaccida and lower edge of scutum
Posteriorly – opened to post. Pouch of Von Troeltsch,
posterior malleal fold
- Ventilation route is independent of the upper unit of
attic
- Ventilation through posterior pouch of Von Troeltsch –
rough and narrow when compared to tympanic
isthmus

37. Prussak’s space dysventilation and attic
cholesteatoma
 COM – thick mucus secretion – closure of
post. Pouch of Von Troeltsch
- selective dysventilation of Prussak’s space
– pars flaccida retraction pocket with adhesion
to malleus neck
- Initially sac of the retraction pocket remains
small and superficial to ossicles
- Continued retraction and keratin accumulation
– enlargement of sac and expansion via
pathways of least resistance

39. PROTYMPANUM
Lies ant. to a frontal line drawn through the ant.
Margin of tympanic annulus
Anteriorly – Eustachian tube
Posteriorly – Mesotympanum
Laterally – Lateral lamina ( separates PT from
mandibular fossa)
Medially – cochlea posteriorly and carotid canal
anteriorly
Roof – bony semicanal for Tensor tympani muscle and
TTF
SUPRATUBAL RECESS
- Superior extension of protympanum
- Lies between superior border of tympanic
orifice of ET and TTF

40. Hypotympanum
Lies below a horizontal plane from inf. margin of fibrous
annulus to inferior margin of cochlear promontory
Five walls
Anterior wall – carotid canal medially and
dense bone laterally
Posterior wall – inferior part of styloid complex
and vertical segment of facial nerve canal
(may contain retrofacial cells)
Outer wall – tympanic bone
Medial wall – lower part of promontory and
petrous bone
Inferior wall – thin bony plate separating from
jugular bulb

41. RETROTYMPANUM
Posterior part of tympanic cavity medial &
posterior to the tympanic annulus
Vertical segment of Facial Nerve & the PE
divides it-
1. The Lateral Space( Facial Recess)
Medially – facial canal and pyramidal eminence
Laterally – chorda tympani
Superiorly – Incudal buttress
Inferiorly – chordo-facial angle (180 - 300)
Chordal ridge – divides facial recess into
- Facial sinus (superiorly)
- Lateral tympanic sinus (inferiorly)

43. 2. The Medial Space
Also called as the Tympanic sinus
Ponticulus divides tympanic sinus to
a. Posterior Tympanic Sinus(Superiorly)
b. Sinus tympani( Inferiorly)- Largest sinus of
Retrotymp.
• In 10% population the sinus tympani and
posterior tympanic sinus form one confluent
recess
• Based on depth sinus tympani is of 3 type
i) Type A(Shallow)
ii) Type B(intermediate)
iii) Type C(very deep)

44. Mesotympanum
Narrowest & biggest compartment
Boundaries
 Medially – promontory
 Laterally – pars tensa
 Anteriorly – protympanum
 Posteriorly – retrotympanum
 Inferiorly – hypotympanum
 Superiorly – Tympanic diaphragm
Acts like a channel allowing air coming from ET
to pass through the Tympanic Isthmus upward
to provide aeration of whole attic

45. TYMPANIC MEMBRANE POUCHES
1. Anterior pouch of Von Troeltsch
- Situated between Anterior Malleal fold and
pars tensa
- Communicates with supratubal recess and
protympanum
2. Posterior pouch of Von Troeltsch
- Situated between posterior Malleal fold and
pars tensa
- Develops posteroinferiorly and opens in the
most cranial portion of mesotympanum
- Main route of ventilation of Prussak’s space