Simple way for approaching anatomy of middle ear. Reference : Dhingra Gray's anatomy

1. Presented by:
Ayush Bakhrel
Anuj Banjara

2. What is Middle Ear?
Middle Ear is an air-filled,
mucous membrane lined space
in the temporal bone between
the tympanic membrane
laterally and the lateral wall of
the internal ear medially .

3. Embryology
First pharyngeal pouch
Pharyngotympanic tube
Middle ear cavity
Mastoid antrum
First pharyngeal arch
Malleus
Incus
Tensor tympani muscle
Ligament of malleus

4. Embryology
Second pharyngeal arch
Stapes
Stapedius muscle
First pharyngeal membrane
Tympanic membrane

6. Division of Middle Ear

7. Epitympanum
Hypotympanum
Mesotympanum
MIDDLE EAR
Pars tensa

9. • Epitympanum(Attic)- Lying above pars tensa
but medial to the Shrapnell’s membrane and
bony lateral attic wall)
• Mesotympanum- Lyinng opposite to the pars
tensa
• Hypotympanum – lying below the level of Pars
tensa
Division of Middle Ear

10. Tympanic Cavity

11. Boundaries of Middle Ear
Middle Ear consists of
1. Roof
2. Floor
3. Anterior wall
4. Posterior Wall
5. Medial Wall
6. Lateral Wall

14. Roof ( Tegmental wall)
The tegmental wall (roof) of
the middle ear consists of a
thin layer of bone, which
separates the middle ear
from the middle cranial
fossa. This layer of bone is
the tegmen tympani on the
anterior surface of the
petrous part of the temporal
bone.

16. ROOF(TEGMENTAL WALL)
= TERRACE= TEGMEN TYMPANI

17. • Floor (Jugular wall)
Jugular wall (floor) of the
middle ear consists of a
thin layer of bone that
separates it from the
internal jugular vein.
• Near the medial border of
the floor is a small
aperture,through which
the tympanic branch from
the glossopharyngeal
nerve [IX] enters the
middle ear.

19. ROOF(TEGMENTAL WALL)
= TERRACE= TEGMEN TYMPANI
FLOOR ( JUGULAR WALL)
Internal Jugular
Vein

20. Membranous wall
(Lateral wall)
The membranous (lateral) wall of
the middle ear consists almost
entirely of the tympanic
membrane, but because
the tympanic membrane does
not extend superiorly into
the epitympanic recess , the
upper part of the membranous
wall of the middle ear is the bony
lateral wall of the epitympanic
recess.

21. ROOF(TEGMENTAL WALL)
= TERRACE= TEGMEN TYMPANI
FLOOR ( JUGULAR WALL)
Internal Jugular
Vein
Lateral Wall
= Tympanic
membrane

23. Mastoid wall(Posterior)
The mastoid (posterior) wall of the
middle ear is only partially complete. The
lower part of this wall consists of a bony
partition between the tympanic cavity
and mastoid air cells . Superiorly, the
epitympanic recess is continuous with
the aditus to the mastoid antrum .
Associated with the mastoid wall are :
• the pyramidal eminence, a small
elevation through which the tendon of
the stapedius muscle enters the middle
ear
• the opening through which the chorda
tympani nerve, a branch of the facial
nerve [VII] , enters the middle ear.

25. ROOF(TEGMENTAL WALL)
= TERRACE= TEGMEN TYMPANI
FLOOR ( JUGULAR WALL)
Internal Jugular
Vein
Lateral Wall
= Tympanic
membrane
Mastoid antrum
Pyramidal
eminence(Staped
ius muscle enters
middle ear)
Chorda
tympani

26. Anterior wall
The anterior wall of the middle ear is only
partially complete. The lower part consists
of a thin layer of bone that separates the
tympanic cavity from the internal carotid
artery. Superiorly, the wall is deficient
because of the presence of:
• a large opening for the entrance of the
pharyngotympanic tube into the middle ear
• a smaller opening for the canal containing
the tensor tympani muscle.
The foramen for the exit of the chorda
tympani nerve from the middle ear is also
associated with this wall

28. ROOF(TEGMENTAL WALL)
= TERRACE= TEGMEN TYMPANI
FLOOR ( JUGULAR WALL)
Internal Jugular
Vein
Lateral Wall
= Tympanic
membrane
Mastoid antrum
Pyramidal
eminence(Staped
ius muscle enters
middle ear)
Chorda
tympani
Pharyngotympanic
tube
Tensor tympani
Internal Carotid
Artery
Chorda
tympani

29. Labyrinthine wall(Medial
wall)
The labyrinthine (medial) wall of the
middle ear is also the lateral wall of
the internal ear
•A prominent structure on this wall
is a rounded bulge (the promontory)
produced by the basal coil of the
cochlea, which is an internal ear
structure involved with hearing.

30. Labyrinthine wall
Associated with the mucous
membrane covering the promontory
is a plexus of nerves (the tympanic
plexus) .
Additionally, a branch of the
tympanic plexus (the lesser petrosal
nerve) leaves the promontory and
the middle ear,
travels across the anterior surface
of the petrous part of the temporal
bone, and leaves the middle cranial
fossa through
the foramen ovale .

31. ROOF(TEGMENTAL WALL)
= TERRACE= TEGMEN TYMPANI
FLOOR ( JUGULAR WALL)
Internal Jugular
Vein
Lateral Wall
= Tympanic
membrane
Mastoid antrum
Pyramidal
eminence(Staped
ius muscle enters
middle ear)
Chorda
tympani
Pharyngotympanic
tube
Tensor tympani
Internal Carotid
Artery
Promontory
Chorda
tympani

32. Oval window and Round Window

33. Oval Window
The oval window is
posterosuperior to the
promontory.
It is the point of attachment
for the base of the stapes
(footplate), and ends the
chain of bones that transfer
vibrations initiated by the
tympanic membrane to the
cochlea of the internal ear.

34. ROOF(TEGMENTAL WALL)
= TERRACE= TEGMEN TYMPANI
FLOOR ( JUGULAR WALL)
Internal Jugular
Vein
Lateral Wall
= Tympanic
membrane
Mastoid antrum
Pyramidal
eminence(Staped
ius muscle enters
middle ear)
Chorda
tympani
Pharyngotympanic
tube
Tensor tympani
Internal Carotid
Artery
Promontory
Oval window
(Posterosuperiorly)
Chorda
tympani

35. The round window is posteroinferior to the
promontory.
Posterior and superior to the oval window is
the
prominence of the facial canal which is a ridge
of bone produced by the facial nerve
as it passes through the temporal bone.
Above and posterior to the prominence of the
facial canal is a prominence of the lateral
semicircular canal produced by the lateral
semicircular canal.

37. ROOF(TEGMENTAL WALL)
= TERRACE= TEGMEN TYMPANI
FLOOR ( JUGULAR WALL)
Internal Jugular
Vein
Lateral Wall
= Tympanic
membrane
Mastoid antrum
Pyramidal
eminence(Staped
ius muscle enters
middle ear)
Chorda
tympani
Pharyngotympanic
tube
Tensor tympani
Internal Carotid
Artery
Promontory
Oval window
(Posterosuperiorly)
Round window
Prominence of
facial canal
Prominence of lateral
semicircular canal
Chorda
tympani

38. Mastoid Area
Posterior to the epitympanic recess of the middle ear is
the auditus to the mastoid antrum, which is the opening
to the mastoid antrum .
The mastoid antrum is a cavity continuous with
collections of air-filled spaces (the mastoid cells) ,
throughout the mastoid part of the temporal bone,
including the mastoid process.
The mastoid antrum is separated from the
middle cranial fossa above by only the thin tegmen
tympani.
The mucous membrane lining the mastoid air cells is
continuous with the mucous membrane throughout the
middle ear. Therefore infections in the middle ear can
easily spread into the mastoid area.

40. Pharyngotympanic tube
The pharyngotympanic tube connects the
middle ear with the nasopharynx and equalizes
pressure on both sides of the tympanic
membrane. Its opening in
the middle ear is on the anterior wall. It
consists of:
• a bony part (the one-third nearest the middle
ear)
• a cartilaginous part (the remaining two-thirds
) .

42. Auditory Ossicles
Consists of 3 main ear ossicles:
1. Malleus (hammer)
2. Incus(anvil)
3. Stapes(stirrup)

43. Malleus(Hammer, largest)
Largest of the auditory ossicles.
It is attached to the tympanic membrane.
Its part are:
•Head
•Neck
•Anterior and lateral process
•Handle
The anterior process is attached to the anterior
wall of the middle ear by a ligament.
• The lateral process is attached to the anterior
and posterior malleolar folds of the tympanic
membrane.

45. Incus
It consist of :
• Body of the incus
• Long and short limbs
• The enlarged body of the
incus articulates with the
head of the malleus.
• The long limb extend
downward and articulated
with the stapes.
• The short limb extends
posteriorly and attached by
a ligament to upper
posterior wall of middle ear.

46. Stapes(Smallest)
It is the most medial bone
-it is attached to the oval window.
- It consists of:
- Head
- Anterior and Posterior limb
- Base
• The head : directed laterally and
articulates with the long process of
the incus.
• The two limbs separate from each
other and attach to the oval base.
• The base of the stapes fits into the
oval window .

47. Muscle Origin Insertion Innervation Function
Tensor
tympani
Cartilaginous part of
pharyngotympanic
tube,
greater wing of
sphenoid, its
own bony canal
Upper part of
handle of
malleus
Branch from
mandibular
nerve [V3]
Contraction pulls
handle of
malleus medially,
tensing tympanic
mem brane
Stapedius Attached to inside of
pyramidal eminence
Neck of stapes Branch of
facial nerve
[VII]
Contraction pulls
stapes posteriorly,
preventing
excessive
oscillation

48. • Major vessels
– Anterior tympanic branch of maxillary artery –
tympanic membrane
– Stylomastoid branch of posterior auricular artery –
middle ear and mastoid air cells
• Minor vessels
– Petrosal and superior tympanic branch of middle
meningeal
– Branch of artery of pterygoid canal
– Tympanic branch of internal carotid
Arterial Supply

49. Venous Supply
• Pterygoid venous plexus
• Superior petrosal sinus
Lymphatic Drainage
Retropharyngeal nodes—upper jugular chain

50. • Function
– Couples sound energy to cochlea
– Physical protection for cochlea
– Impedance matching
• Hydraulic action of tympanic membrane
• Lever action of ossicles
• Eustachian tube-equalizes pressure and keep tympanic
membrane in neutral positon
– Attenuation of sound.
Physiology

52. • CSOM(Chronic Suppurative Otitis Media)
– Perforated tympanic membrane with persistent
drainage from the middle ear (lasting >3months )
– Conductive hearing loss
• Cholesteatoma
– Abnormal, noncancerous skin growth that can
develop in the middle section of your ear, behind the
eardrum
– Acquire ear infections repeatedly early in life
Clinical Aspect

53. • Gray’s anatomy for student
• Guyton and Hall Text Book of Physiology(13th
edition)
• Ear, Nose and Throat – PL Dhingra(6th edition)