one of the imp topics in ENT that should be understood very thoroughly if u want to pursue as an otologist.I tried to simplify the topic with simple diagrams and models for better understanding .

1. Spaces of middle ear and their
surgical importance
Speaker-DR SOUMYA

2. OVERVIEW
• EMBRYOLOGY
• MIDDLE EAR FOLDS
• MIDDLE EAR SPACES
• SURGICAL IMPORTANCE

3. MIDDLE EAR FOLDS DEVELOPMENT
• 3rd and 7th fetal months -mesenchymal
tissue of the middle ear cleft is gradually
absorbed.
• At the same time, the primitive tympanic
cavity develops by a growth of an
endothelium-lined fluid pouch extending from
the Eustachian tube into the cleft.

4. 4

5. • The terminal end of the tubotympanic recess
buds into four sacci: the saccus anticus, the
saccus medius, the saccus superior, and the
saccus posticus
• These sacci enlarge in the middle ear cleft n
replace the pre-existing mesenchyme.

6. • walls of the pouches- mucosal lining of middle
ear cavity.
• At the plane of contact between two -
pouches, mucosal folds are formed.
• Between the mucosal layers of the folds
remnants of the mesenchyme -transform into
ligaments and blood vessels supplying the
“viscera” of the tympanic cavity.

7. MUCOSAL FOLDS
• Middle ear mucosal folds pass from the walls
of the middle ear to its contents
• carry ligaments
• blood vessels to the ossicles.
• Forms compartment
• Directs cholesteatoma spread
• Not an effective barrier though

8. Embryology of MiddleEar
Compartments
.
• These sacci expand progressively to replace
middle ear mesenchyme and mastoid
mesenchyme.
• 1ST arch cartilage-head of malleus
Body of incus
• 2nd arch cartilage-HOM,Long process of incus
Stapes crurae
Footplate –otic capsule

10. Saccus Anticus:
• anterior pouch of Von Troeltsch
• part of the anterior attic
compartment
• Upward extension is limited
upto semicanal for tensor
tympani, wherein it comes in
contact with the saccus
medius’s anterior saccule part
• This point of contact forms the
Tensor fold, and above this will
be the anterior compartment of
attic

11. Saccus Medius:
• Forms most part of the attic
• Divides into 3 saccules
• Anterior saccule: the anterior
compartment of attic
• Medial saccule: Prussacks
space
• the superior incudal space by
growing over the incus body
• Posterior saccule: extends
posteriorly to the anterior crus
of stapes, medial to the long
process of incus
• pneumatises that part of
mastoid air cells in petrous
bone

12. Saccus superior:
• posterior pouch of Von
Troeltsch
• inferior incudal space
• Extending posteriorly
crosses HOM and long
crus of the incus then
over saccus posticus and
stapedial tendon and
towards antrum
• pneumatises the
squamous part of mastoid

13. Saccus Posticus:
• stapedial folds,
• sinus tympani,
• round window niche
• lower half of oval
window niche
• Extends along the
hypotympanum and
under the stapedial
tendon
• pneumatises the
posterior tympanic sinus

15. KORNER’S SEPTUM
• The plane of fusion between the posterior
saccule of the saccus medius, and the saccus
superior.
• SM- which forms the medial part of mastoid air
cells system
• SS-which forms the lateral part of mastoid air
cells system,
• usually it breaks down.
• If the breakdown fails, a bony septum persists
between the two parts, called the Korner’s
septum

16. Ligaments & folds in the middle ear:
• Malleus
• Superior malleolar fold
• Anterior malleolar fold
• Lateral malleolar fold
• Posterior malleolar fold
• Tensor tympani fold
• Incus
• Superior incudal fold
• Medial incudal fold
• Lateral incudal fold
• Interossicular fold
• Stapes
• Obturator fold and other
stapedial folds
• Posterior incudal ligament
• Superior incudal ligament
• Superior malleolar ligament
• Anterior malleolar ligament
• Posterior malleolar ligament

17. The Posterior Malleal Fold
• inserts on the posterior portion of the neck of
the malleus.
• It involves the upper portion of the handle of
the malleus
• merges superiorly with the lateral
incudomalleal fold.
• It inserts posteriorly on the posterior
tympanic spine and represents the medial wall
of the posterior pouch of von Tröltsch.

18. Anterior Tympano-Malleal Fold
• arises from the anterior portion of the neck of
the malleus and inserts anteriorly on the
anterior tympanic spine.
• It forms the medial wall of the anterior pouch
of von Tröltsch.

19. • ANTERIOR MALLEAL LIGAMENT
• von Tröltsch in 1856
• part of the tympanic diaphragm.
• origin neck of the malleus and extends to the
anterior attic bony wall.
• reflected from the lateral wall of the middle
ear over the anterior process and the anterior
part of the chorda tympani.
It represents the anterior limit of Prussak’s
space

20. LATERAL MALLEAL FOLD
• Helmholtz in 1868.
• Origin: middle portion ofneck of the malleus
• fanlike spread before attaching to the outer attic
wall
• posteriorly, it is confluent with the anterior
portion of the lateral incudomalleal fold
• represents the roof of the Prussak’s space and
the floor of the lateral malleal space.

22. SUPERIOR MALLEAL FOLD
• Origin:superior surface of the malleus head
insertion: the tegmen in a transversal plane.
• Contains superior malleal ligament
• divides the attic into
• 1. anterior mallelolar space
• 2. anterior epitympanic recess
.

24. LATERAL INCUDOMALLEAL FOLD
• Part of the tympanic diaphragm.
• Superior to:lateral malleal ligamental fold
separates the upper lateral attic space from
the lower lateral attic space.
• 1 mm higher than the roof of the Prussak’s
space.
• Anteroinferiorly insertion: neck of the
malleus.

25. • MEDIAL INCUDAL FOLD
• located between the long process of the incus
and the tendon of the stapedial muscle as far
as the pyramidal eminence.
• SUPERIOR INCUDAL FOLD (SIF)
• extends like the superior incudal ligament
from the superior surface of the incudal body
to the tegmen.
• It divides the posterior attic into lateral and
medial attic.

26. • POSTERIOR INCUDAL FOLD
• The posterior incudal fold is the fold that runs
between the fibres of the posterior incudal
ligament

27. TENSOR TYMPANI FOLD (TTF)
• part of the tympanic diaphragm.
• It arises posteriorly from the tensor tympani
tendon, about 1.5 mm lower than the roof of
Prussak’s space.
• It runs anteriorly towards the anterior wall of
the attic inserting into a transverse crest: the
supratubal ridge.

28. • Medially inserts on the bony canal of the TTM
laterally inserts on the anterior malleal
ligament.
• The lateral part of the tensor in close
relationship with anterior portion of chorda
tympani.
• It separates
ANTERIOR EPITYMPANIC RECESS
superiorly from the
SUPRATUBAL RECESS inferiorly.

29. In the majority of ears,
the TTF is incomplete;
this allows a direct
communication from the
Eustachian tube and
supratubal recess to the
anterior epitympanic
recess and then to the
posterior attic

30. Supratubal Recess (STR)
• superior extension of the protympanum
• space lying between the superior border of
the tympanic orifice of the Eustachian tube
and the tensor tympani fold.
• It lies below the anterior attic from which it is
separated by the tensor tympani fold.

41. EPITYMPANIC DIAPHRAGM
• Chatellier and Lemoine introduced the
concept of the “epitympanic diaphragm” in
1946, upon which the modern theories of
tympanic ventilation have been developed.
• Palva et al. revised Chatellier’s concept
.

42. • Comprises of 3 malleolar ligaments:
– Anterior malleolar ligament
– Lateral malleolar ligament
– Posterior malleolar ligament
• The posterior incudal ligament and fold
• Tensor tympani fold
• Lateral incudal fold.
Epitympanic diaphragm:

44. • The tympanic diaphragm is not fully horizontal
because its components are on different
levels.
• It separates the upper unit of the attic
superiorly from the mesotympanum and the
lower unit of the attic, the Prussak’s space,
inferiorly.

45. • Anterior pouch of von Tröltsch: between the
anterior malleal fold
• the pars tensa
• Posterior pouch of von Tröltsch: between the
posterior malleal fold
and the pars tensa

46. • TYMPANIC ISTHMUS
• The Eustachian tube opens in mesotympanum
• , the attic and the mastoid are isolated from
the mesotympanum by the tympanic
diaphragm.
• Attic aeration occurs through a 2.5 mm
opening in the tympanic diaphragm called the
TYMPANIC ISTHMUS.

47. ANTERIOR TYMPANIC ISTHMUS
• TTM anteriorly and the stapes
posteroinferiorly.
• The diameter 1 to 3 mm.
• It is a large open communication with the
anterior epitympanum,
• always present.
• Ventilates anterior epitymanum and upper
unit (superior attic)

48. POSTERIOR TYMPANIC ISTHMUS
• between the short
process of the
incus
and the stapedial
muscle.
• inconsistent.

49. STAPEDIAL FOLDS
• There are five folds around the stapes….
OBTURATOR STAPEDIS (between the crura of the
stapes)
• ANTERIOR STAPEDIAL FOLD (between
promontory and ant crus)
• POSTERIOR STAPEDIAL FOLD (between
promontory and post crus)
• PLICA STAPEDIUS (between the post crus and
pyramidal eminence)
• SUPERIOR STAPEDIAL FOLD (between either of
the crura and facial canal)

50. MIDDLE EAR SPACES
• MIDDLE EAR COMPARTMENTS
. The middle ear cavity divided into five
compartments:
• MESOTYMPANUM in the centre
• EPITYMPANUM superiorly
• PROTYMPANUM anteriorly
• HYPOTYMPANUM inferiorly &
• RETROTYMPANUM posteriorly

51. RETROTYMPANUM
• . The retrotympanum is the site of the highest
incidence of middle ear pathologies especially
retraction pockets and cholesteatoma

53. ANATOMY OF THE RETROTYMPANUM
• four spaces:
• Two spaces medial to the vertical segment of
the FN and the pyramidal eminence two
spaces lie lateral to them.
• These spaces are separated from each other
by the bridges and the eminences of the
posterior wall of the middle ear cavity.
• The pyramidal eminence -fulcrum of the
retrotympanum.

54. • The pyramidal eminence
– The pyramidal eminence is situated at the center of the
posterior wall immediately behind the oval window; it
is about 2 mm height.
• The chordal eminence:
– The chordal eminence is situated lateral to the
pyramidal eminence and 1 mm medial to the tympanic
membrane. The chordal eminence shows a foramen:
the iter chordæ posterius.
• The styloid eminence
– The styloid eminence or Politzer eminence is a
recognized smoothed elevation at the inferior part of
the posterior wall; it represents the base of the styloid
process.
3 Retrotympanum eminences:

55. • The chordal ridge of Proctor
– The chordal ridge runs laterally and transversally from the
pyramidal eminence to fuse with the chordal eminence.
• The pyramidal ridge
– The pyramidal ridge is very prominent. It runs inferiorly from
the base of the pyramidal eminence to the styloid eminence. It
could be absent.
• The styloid ridge
– The styloid ridge connects the styloid prominence to the
chordal eminence.
• Subiculum: A ridge of bone running from the posterior lip of round
window niche to the styloid eminence.
• Ponticulus: a ridge of bone extending from the pyramidal eminence
to the promonotary.
5 Retrotympanum ridges:

58. FACIAL RECESS
• medially facial canal and the pyramidal
eminence
• laterally by the chorda tympani.
• Superiorly incudal buttress, bony boundary of
the incudal fossa, which lodges the short
process of the incus.
• The incudal buttress separates the facial
recess from the aditus ad antrum.

60. • Inferiorly, the facial recess is limited by the
chordo-facial angle ranges from 18° to 30°;
• distance between the origin of the chorda
tympani and the short process of the incus
ranges from 5 to 10 mm.

61. • size is variable among individuals
• it is near adult size at birth.
• It measures about 2 mm at the level of the
round window and 3 mm at the level of the
oval window.

62. • The chordal ridge, which runs
between the pyramidal
eminence and the chordal
eminence, divides the facial
recess into the FACIAL SINUS
superiorly and the LATERAL
TYMPANIC SINUS inferiorly.

63. SURGICAL APPLICATION
• The facial recess serves as a posterior window to
reach the middle ear from the mastoid cavity,
• enables visualization of the OW and ponticulus
superiorly and the RW and subiculum inferiorly.
• It is done by a transmastoid drilling of the
posterior wall of the facial recess, between the
chorda tympani laterally and the facial nerve
medially.
• This surgical approach is called TRANSMASTOID
POSTERIOR TYMPANOTOMY

65. MEDIAL SPACES OF RETROTYMPANUM
• depressions in the posterior wall of the middle
ear between the
• facial nerve and pyramidal eminence laterally
• labyrinth medially….

66. TYMPANIC SINUS
• The ponticulus, which runs from the
promontory to the pyramidal eminence,
divides the tympanic sinus in two spaces:
• POSTERIOR TYMPANIC SINUS
superiorly
• SINUS TYMPANI inferiorly.

67. • POSTERIOR TYMPANIC SINUS Surgical
Application
• present in most middle ears.
• It lies superior to the ponticulus, medial to the
pyramidal eminence and facial nerve.
• It is about 1 mm deep and about 1.5 mm long
• During middle ear surgery, in order to reach
the posterior tympanic sinus, section of the
stapedial tendon and drilling of the pyramidal
process may be required.

68. SINUS TYMPANI
• largest sinus of the retrotympanum.
• It lies medial to the mastoid portion of the
facial nerve,
• lateral to the posterior semicircular canal.
• superiorly :ponticulus and the pyramidal
eminence
• inferiorly :subiculum and the styloid
eminence.

69. • great variability in size , shape and depth.
• Its posterior extension varies between 0.2 and
10 mm with an average of 2 mm.
• 10 % of the population, the sinus tympani and
posterior tympanic sinus form one confluent
recess.

70. Surgical importance
• During cholesteatoma surgery a good
exposition of the medial boundary of the sinus
tympani is very important, because of two
important risks.
1. potential persistence of disease inside the
sinus due to incomplete removal.
2. The second is the increased risk for ossicular
discontinuity and hearing loss due to
cholesteatoma within the ST, which the
surgeon cannot control

71. CLASSIFICATION OF ST BASED ON
MORPHOLOGY
• CLASSICAL SHAPE: when the sinus is located
between the ponticulus and subiculum lying
medial to the facial nerve and to the
pyramidal process.
• CONFLUENT SHAPE: when an incomplete
ponticulus is present and the ST is confluent
to the posterior sinus.

73. • PARTITIONED SHAPE: when a ridge of bone
extending from the third portion of the facial
nerve to the promontory area is present,
separating the sinus tympani into two
portions (superior and inferior).
• RESTRICTED SHAPE: when a high jugular bulb
is present thus reducing the inferior extension
of the sinus tympani.

75. Based on its depth
• classified into three types with an equal
frequency in the general population.
• Type A Small sinus tympani:-
• it is small and does not reach the level of the
vertical portion of the facial nerve posteriorly.
surgical transcanal access to the sinus tympani
is possible.

76. • Type B deep Sinus Tympani
• intermediate depth; it lies medial to the vertical
portion of the facial nerve but does not extend
posteriorly deeper than the level of the facial nerve.
• A total and clear visualization of such sinus tympani
could not be achieved without the use of an
endoscope.
• Any blind dissection in the sinus tympani without
endoscopic visualization carries a risk of residual
disease or a possible injury to a dehiscent facial nerve
or a high jugular bulb.

77. • Type C deep Sinus Tympani with post. Extension;
• it extends posteriorly more deeply than the
vertical portion of the facial nerve.
• This type is frequently seen in a well-
pneumatized mastoid.
• Despite the use of an otoendoscope, the
pathology of such deep sinus could not be
explored entirely from the middle ear; therefore,
access should be obtained through a
TRANSMASTOID RETROFACIAL APPROACH.

79. CLASSIFICATION ST’S
DEPTH BASED ON AXIAL CT SCAN.
• A limited sinus tympani
• B deep sinus tympani with medially
• extension respect the facial nerve
• C deep sinus tympani with posterior extension
respect the facial nerve

80. Anatomy of the Attic(The
Epitympanum)
• The attic is the part of the tympanum situated
above an imaginary plane passing through the
short process of the malleus.
• The attic occupies approximately one-third of
the vertical dimension of the entire tympanic
cavity and lodges the head and neck of the
malleus, the body, and the short process of
the incus.

81. • Upper Unit of the Attic
• lies above the tympanic diaphragm.
• A communication between both spaces for
ventilation purposes is only possible through
an opening of the tympanic diaphragm, called
the tympanic isthmus
• The tympanic isthmus is situated between the
tensor tympani muscle anteriorly and the
posterior incudal ligament posteriorly.

82. BOUNDARIES
• LATERAL WALL – inferiorly by Shrapnell’s membrane
and superiorly by a bony wall, called the outer attic
wall.
• MEDIAL WALL -- part of the medial wall situated
above the tympanic segment of the facial nerve and
tensor tympani muscle. It contains the lateral
semicircular canal.
• POSTERIOR WALL - occupied almost entirely by the
aditus ad antrum. It is 5–6 mm high
• INFERIOR - tympanic diaphragm divides the attic into
an upper unit situated above the tympanic
diaphragm and a lower unit of the attic (the Prussak’s
space), which is below the diaphragm.
• Anteriorly by tympanosquamous suture

83. • Divided into 2 compartments:
– Anterior epitympanum.
– Posterior epitympanum.
• Posterior epitympanum divided into 2:
– Medial portion
– Lateral portion
• Lateral portion again divided to 2 parts:
– Superior lateral attic
– Inferior lateral attic
• Prussak space:
• Anterior pouch of Von Tröltsch :
• Posterior pouch of Von Tröltsch :
Epitypanic spaces:

84. • DIVISION OF UPPER
ATTIC
• several folds and
ligaments in the
perpendicular planes
lead to
further divisions and
spaces of the upper
unit of the attic

86. • Medial Posterior Attic
• It is bounded by the lateral semicircular canal
and the Fallopian canal medially and the
ossicles and the superior incudal fold laterally.
• The distance between the lateral semicircular
canal and the incus body is 1.7 mm.
• larger compartment of the posterior attic.

88. • Lateral Posterior Attic
• Anterior Attic or Anterior Epitympanum
• The anterior epitympanum is divided into two
spaces by the cog.
• The cog is a bony crest that extends inferiorly
from the tegmen; it is superior to the
cochleariform process and anterosuperior to the
malleus head.
• It divides the anterior attic into a small posterior
space, the anterior malleal space, and large
anterior space: the anterior epitympanic recess

90. • Anterior Epitympanic Recess (AER)
• ANTERIOR EPITYMPANIC SINUS / ANTERIOR
EPITYMPANIC SPACE / SINUS EPITYMPANI
• Superiorly: anterior part of the tegmen tympani
– • Anteriorly: zygomatic root
– • Posteriorly: cog
– • Laterally: scutum
– • Medially geniculate ganglion
– • Floor: cochleariform process and the TTF

92. • Lower Unit of the Attic
• Prussak’s space is formed from the posterior
pouch of von Tröltsch as a prolongation of the
superior saccus, replacing the mesenchymal
tissue between the neck of the malleus and
Shrapnell’s membrane.
• The aeration pathway remains the same as
the route of origin which is the posterior
pouch of von Tröltsch.

93. • PRUSSAK’S SPACE
• The Prussak’s space is situated inferior to the
tympanic diaphragm and represents the lower
unit of the attic.
» ROOF is the lateral malleal fold
» FLOOR is formed by the neck of the malleus.
» ANTERIOR LIMIT is the anterior malleal fold.
» LATERAL WALL is formed by the pars flaccida and the
lower edge of the outer attic wall
» POSTERIOR WALL is opened to the posterior pouch of von
Tröltsch and then to the mesotympanum.

94. protympanum
The protympanic space is a pneumatic portion
of the middle ear that lies anteriorly to the
mesotympanum and inferiorly to the AES
• . The cochleariform process and the tensor
fold with the tensor tympani canal represent
the upper limit of protympanic space
• posteriorly promontorium.

95. • less important in middle ear surgery because
chronic disease seldom involve this recess.
• but some important structures are in there.
Tympanic portion of Eustachian tube starts
from the protympanum and is usually 11–12
mm in diameter. It can present different
shapes:
rectangular(35%),
triangular (20%)
irregular shape (45%) [31].

96. • Above and medially to the Eustachian tube
opening runs the internal carotid artery.
• Bone over this structure couldbe thick or
pneumatized with some cells in there
(protympanic cells).
 This variant is important because we can
find a bulging of the carotid artery, in some
cases
could be uncovered.
we find protympanic cells in patients with
cholesteatoma involving the protympanic
space, we have to pay more attention because
these cells might hide the presence of
cholesteatoma persistence.

97. SURGICAL SIGNIFICANCE
COMPARTMENTAL SPREAD OF DISEASE
• By compartmentalisation of the middle ear, these
folds may limit the disease process for a SOME
time in one or more compartments, before
spreading to other regions
• If cholesteatoma is contained in its sac and
compartment, it may be possible to remove the
sac entirely and preserve the underlying mucosal
folds and the Viscera

98. • Surgery can thus be aimed at establishing proper
communication between attic and the
mesotympanum, rather than any radical
procedures, like
1.Removal of the tensor fold often along with
tensor tympani tendon
2.Removal of incus body and leaving incus long
process attached to stapes and medialising the
tympanic membrane over the long process of
incus
If communication is thus reestablished there will
not be the need to remove the mastoid cells in
non suppurating ears

99. PATHWAYS OF SPREAD OF
CHOLESTEATOMA

100. A.POSTERIOR EPITYMPANUM
• 1. prussacks space
Superior incudal
space
aditus
antrum
• 2.floor of prussacks
space
Post.
Space of von troeltsch
mesotympanum

101. .
s
u
p
e
r
i
o
r
i
n
c
1.Black arrow
. superior incudal space
. aditus ad antrum
. mastoid antrum (chol lateral
to ossicles)
. mastoid air cells
2.dotted arrow
post. Mesotympanum (thru
floor of P S into post pouch of
von troeltsch)

102. POSTERIOR MESOTYMPANUM
• SINUS TYMPANI and
FACIAL RECESS
Through posterior tympanic
isthmus
• Inf incudal space
• Aditus and then
antrum
• Extension to mastoid (sac
remains medial to
ossicles)
• FACIAL RECESS
Through posterior tympanic
isthmus
• Inf incudal space
• Aditus and then
antrum
• Extension to mastoid (sac
remains medial to ossicles
heads)

103. ANTERIOR EPITYMPANUM
• Anterior space of von
troelstch
• Mesotympanum
• invagination of
epitympanum ant to
malleus head & neck
creates cholesteatoma
that threatens horizontal
F. N. and geniculate
ganglion leading to 7th N
dysfunction
. Ant to head of malleus, supratubal recess
. Geniculate ganglion of 7th N
involves, facial N dysfunction
. Downward growth into anterior
mesotympanum
(protympanum) via Ant. Pouch of
von troltsch

104. VENTILATORY ANATOMY

106. epitympanum

108. Prussak’s Space Dysventilation & Attic
Cholesteatoma
• The possibility of closure of the posterior
pouch of von Tröltsch following thick mucus
secretion formation during chronic
inflammatory otitis is high.
• This event may cause a selective
dysventilation of Prussak’s space and
development of pars flaccida retraction pocket
with adhesion to the malleus neck.

109. • THANK YOU FOR YOUR PATIENCE