6. PINNA
• Single piece elastic
cartilage
• Covered with
perichondrium and
skin(except lobule and
outer part of external
auditory canal)
• Ligaments
• Muscles (supplied by
facial nerve),
• Muscles are not well
developed in human
7.
8. INCISURA TERMINALIS
◦ Endaural approach-inscion made
on this area will not cut through
the cartilage in surgery of EAC
or Mastoid
PINNA Contd.
9. APPLIED ANATOMY
Tragal cartilage, perichondrium
from tragus, concha, fat from
lobule – reconstruction
surgery for middle ear
Conchal cartilage – correct
depressed nasal bridge
Composite graft of skin &
cartilage from pinna – repair the
defects of nasal ala
10. NERVE SUPPLY - PINNA
Greater auricular nerve
◦ most of the medial
surface of pinna
◦ posterior part of
lateral surface
Lesser occipital
◦ upper part of
medial surface
Auriculo temporal
◦ tragus
◦ crus of helix
◦ adjacent part of helix
11. Auricular branch of vagus
◦ concha
◦ corresponding eminence on medial surface
Facial nerve
◦ distributed with fibers of auricular branch of
vagus
◦ concha
◦ retroauricular groove
NERVE SUPPLY – PINNA Contd
15. EXTERNAL AUDITORY
CANAL
Outer part(cartilaginous) directed
upwards, backwards & medially
Inner part (bony) directed
downwards, forwards & medially
Pinna pulled upwards,
backwards &
laterally(make it straight)
16. CARTILAGINOUS PART
Outer 1/3rd &
8mm canal
Continuation of cartilage which forms
the frame work of pinna
◦ Fissures of Santorini
◦ Through them parotid or superficial mastoid
infection can appear in the canal or vice versa
17. Skin covering the cartilaginous canal is
thick and contains appendages like
1.CERUMINOUS (wax)
2.PILOSEBACEOUS GLANDS
3.HAIR
Skin of Cartilaginous Part
18. BONY PART
Inner 2/3rd & 16mm
Skin
thin
continuous over the TM
No skin appendages
Hair
Ceremonious Glands
ISTHMUS
About 6mm lateral to TM
19. Anterior recess
anteroinferior part of deep meatus
Pool for discharge & debris
Foramen of Huschke
Antero inferior part ofbony canal
Deficiency in children up to ageof 4
Sometimes in adults
Permitting infection to & from parotid
20. NERVE SUPPLY -EAC
Auriculo temporal nerve(V3)
◦ anterior wall & roof
Auricular branch of vagus(X)
◦ posterior wall & floor
Posterior wall of auditory canal also
receives sensory fibres of CNVII through
auricular branch of vagus
21. TYMPANIC MEMBRANE
Forms partition between EAC & middle ear
Obliquely set – 45deg with floor of EAC
Posteriosuperiorpart more lateral than
Anterioinferior part
9-10 mm tall
8-9 mm wide
0.1 mm thick
25. PARS TENSA
Forms most of TympanicMembrane
Periphery is thickened to form afibro
cartilaginous ring –ANNULUSTYMPANICUS,
which fits in tympanicsulcus
Central part of pars tensa is tentedinwards at
the level of tip of malleus – UMBO
Bright Coneof Light – seenradiating fromthe
tip of malleus to periphery in anterioinferior
quadrant
26. PARS FLACIDA
Situated above lateral process of malleus
between the notch of rivinus & anterior &
posterior malleolar fold
Appear slightly Pinkish
27. LAYERS OF TYMPANIC MEMBRANE
Outer Epithelial layer
◦ continuous with skin lining themeatus
Inner mucosallayer
◦ continuous with mucosa of middleear
Middle fibrous layer
◦ encloses the handle of malleus
◦ 3 types of fibres
Radial
Circular
Parobolic
◦ Parsflacida – not organized(FibrousLayers)
28. Mixture of secretions of ceruminous and sebaceous
glands
Two types dry and wet
Dry wax – yellowish or grey, dry and white
Wet wax – yellowish brown, wet and sticky
Contains amino acids, fatty acids, lysozymes and
immunoglobulins.
Has a bactericidal activity
Migrates outside but may get impacted
31. • 36 mm long in adults
• Directed anteriorly, inferiorly & medially from
anterior wall of M.E., forming angle of 450 with
horizontal & sagittal planes
• Enters naso-pharynx 1.25 cm behind posterior
end of inferior turbinate
Page 31
32. Lateral 1/3 is bony
Medial 2/3 is fibro-
cartilaginous.
Junction b/w 2 parts
is isthmus,
narrowest part of
Eustachian Tube.
Page 32
33. Anatomy of
cartilaginous part:
Cartilage plate lies
postero-medially &
consists of medial +
lateral laminae
separated by elastin
hinge. Fibrous tissue +
Ostmann’s fat pad lie
antero-laterally.
Page 33
34. CHARACTERISTIC ADULT INFANT
Length 36 mm 18mm
Angle with horizontal 45° 10°
Lumen Narrow Wide
Angulation at Isthmus Present Absent
Cartilage Rigid Flaccid
Elastic recoil Effective Ineffective
Ostmann’s fat More Less
Difference in adult & infant<7years ET
Page 34
35. Blood supply of ET:
• Ascending pharyngeal artery
• Middle meningeal artery
• Artery of pterygoid canal
• Veins drain into pterygoid venous plexus
Page 35
36. Pearly white semi-
translucent membrane
Obliquely placed faces
laterally,inferiorly
,anteriorly
• 2 parts : pars tensa &
pars flaccida
• 3 layers of pars tensa
: outer epithelial,
middle fibrous & inner
mucosal
Page 36
37. • Fibrous layer is
disorganized in pars
flaccida (Sharpnell’s
membrane)
• Pars tensa thickened
peripherally into
fibrocartilagenous annulus
called annulus tympanicus
which fits into tympanic
sulcus of temporal bone.
• Annulus deficient
superiorly in pars flaccida
and is called notch of
Rivinus
Page 37
38. Nerve supply of TM:
Page 38
• Anterior half of lateral surface :
Auriculo temporal nerve
• Posterior half of lateral surface :
Auricular branch of vagus
• Medial surface :
Tympanic branch of
glossopharyngeal nerve(jacobson
nerve)
V
X
40. Page 15
Walls of the tympanic cavity:
Lateral
Medial
Posterior
Anterior
Floor
41. ROOF
Page 41
• Thin plate of bone called TEGMEN
TYMPANI .
• It also extends posteriorly to form the roof
of the aditus and antrum.
• It seperates tympanic cavity from the
middle cranial fossa.
42. The floor
Page 42
• Thin plate of bone which seperates
tympanic cavity from the jugular bulb.
• 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
43. Page 18
The anterior wall
Lower part
• Thin plate of bone which separates the
cavity from the internal carotid artery.
44. Page 19
The anterior wall
Upper part
• Canal of tensor tympani muscle.
• Eustachian tube opening
47. The promontory
rounded elevation
occupying much
of the central
portion of the
medial wall.
Formed by basal
turn of cochlea.
Oval Window
Round Window
Facial Canal
Grooves- tympanic plexus
Page 47
48. Oval Window
lies Behind and above the promontory
A kidney- shaped
opening that
connects the tympanic cavity with the
vestibule.
Close by a footplate of the stapes.
Its size average 3.25 mm long
and 1.75 mm wide.
Page 48
50. Round window
Page 50
• Lies below and behind the
oval window
• Separated by subiculum
(post extension of
promontory)
• Ponticulus.another ridge
above subiculum and runs to
pyramid on the posterior wall
• Sinus tympani is where
ponticulus and subiculum
meet
• RWM is 2.3×1.9.
• It is placed at right angles to
plane of stapes foot plate
51. Facial nerve canal
Page 51
• The facial nerve canal (or Fallopian canal) runs
above the promontory and oval window in an
anteroposterior direction.
• The facial nerve canal is marked anteriorly by the
processus cochleariformis, a curved projection
of bone, concave anteriorly, which houses the
tendon of the tensor tympani muscle as it turns
laterally to the handle of the malleus.
• The region above the level of the facial nerve canal
forms the medial wall of the epitympanum.
• Behind the oval window, the facial canal starts to
turn inferiorly as it begins its descent in the
posterior wall of the tympanic cavity.
53. • The dome of the lateral semicircular canal
is the major feature of the posterior portion
of the epitympanum, lying posterior and
extending a little lateral to the facial canal
Page 53
54. Posterior wall
Page 54
• Aditus ad antrum
• Fossa incudis for short process of incus
• Bulge produced by lateral semicircular canal
• Pyramidal eminence for stapedius tendon
• Buldge produced by vertical part of facial
nerve
• Sinus tympani
• Facial recess
56. The posterior wall is wider above than below.
Upper part a large irregular opening - the aditus ad antrum,
that leads back from the posterior epitympanum into the
mastoid antrum.
Below the aditus is a small depression, the fossa incudis,
which houses the short process of the incus and its
suspensory ligament.
Below the fossa incudis and medial to the opening of the
chorda tympani nerve is the pyramid, a small hollow conical
projection with its apex pointing anteriorly.
This houses the stapedius muscle and tendon, which inserts
into the posterior aspect of the head of stapes.
The canal within the pyramid curves downwards and
backwards to join the descending portion of the facial nerve
canal.
Page 56
57. Facial Recess
Page 57
runs The
medial
chorda always
to the tympanic
membrane.
The facial recess is a groove which lies between the pyramid with facial
nerve, and the annulus of the tympanic membrane .
The facial recess is bounded:
– Medially by the facial
nerve and
– Laterally by the tympanic
annulus,
– with the chorda tympani
nerve running obliquely
through the wall between
the two.
58. Facial Recess
Page 58
The angle between the facial nerve and the chorda allows a posterior
tympanotomy, allowing access to the middle ear from the mastoid
without disruption the tympanic membrane.
59. Sinus tympani
Page 59
Boundaries:
– Superior: Ponticulus
– Inferior: Subiculum
– Lateral: Mastoid
Segment of Facial
Nerve
– Medial: Posterior
semicircular canal
It evades direct surgical
visualization during
surgery. Site for
cholesteatoma recurrence
63. MUSCLE ORIGIN INSERTION NERVE
SUPPLY
ACTION
Tensor
typmani
Cartilaginous
part of ET, its
own bony
canal
Upper part of
handle of
malleus
Branch from
mandibular
nerve [V3]
tensing
tympanic
membrane to
reduce the
force of
vibrations in
response to
loud noises
Muscles of the middle ear
Page 63
65. Page 40
THE CHORDA TYMPANI NERVE
It enters the tympanic cavity from
the posterior canaliculus at the
junction of the lateral and
posterior walls.
It runs across the medial surface
of the tympanic membrane
between the mucosal and fibrous
layers.
Then passes medial to the upper
portion of the handle of the
malleus above the tendon of
tensor tympani.
leaves thorough petrotympanic
fissure.
carries taste sensation from the
anterior two-thirds of the same
secretomotor fibres to
side of the tongue and
the
submandibular gland.
66. Mastoid air cells
Page 66
• Vary considerably in number, form & size
• Interconnected & lined by squamous non-ciliated
epithelium
• Mastoid processes
can be pneumatic,
sclerosed or mixed
• Mastoid process
develops by the age
of 2 yrs
• Antrum is well
developed at birth
• Aditus ad antrum is
the opening in the
posterior wall of
middle ear and leads
posteriorly to antrum
67. Page 43
Mastoid antrum
and horizontal semicircular canal
• Posteriorly :
communicate by several
openings with mastoid air cells.
Important surgical marks to
mastoid antrum is the
MacEwen’s Triangle
• The roof of mastoid antrum (tegmin antri) separate
it from middle cranial fossa.
• The lateral:
formed by squamous
temporal bone
• Medial wall:
related with the posterior
68. MacEwen’s Triangle
Page 68
• Superior: temporal line
• Anterior: postero-superior
margin of bony external
auditory canal opening
• Posterior: tangent drawn to
mid-point of posterior wall
of external auditory canal
• Contains spine of Henle
• Mastoid antrum lies 12-15
mm deep to triangle
69. Mucosa Of Middle Ear Cleft
Page 69
• Mucus membrane of the nasopharynx is
continuous with that of middle ear ,aditus and
antrum.
• Mucus secreting
• Respiratory type
• Cilia bearing
• Lines the bony wall of the tympanic cavity
and wraps the middle ear structure_ossicles
,muscles ligaments and nerves like
peritoneum wraps viscera of the abdomen.
70. Blood supply
Page 70
• Arteries :
Middle ear is supplied by the following
1)Two main arteries
a) Anterior tympanic branch of maxillary artery
b) Stylomastoid branch of posterior auricular artery
2)Four minor arteries
a)Petrosal branch of middle meningeal artery
b)Superior tympanic branch of middle meningeal artery
c)Branch of artery of pterygoid canal
d)Tympanic branch of internal carotid
• Veins :
Pterygoid venous plexus
Superior petrosal sinus
73. • Meatal segment : 8-10 mm
• Labyrinthine segment : 4 mm
• Tympanic segment : 11 mm
• Mastoid segment : 13 mm
Page 73
74. • Gives 3 branches
in intratemporal
part.
1. Greater
petrosal
nerve
2. Nerve to the
stapedius
3. Chorda
tympani
Page 74
75. Surgical landmarks of facial nerve
Page 75
• Processus cochleariformis
• Oval window and horizontal canal
• Short process of the incus
• Pyramid
• Digastric ridge: just deep to or medial to
the mastoid tip anterior to that is the tip of
the facial nerve
76. • Cartilaginous pointer: sharp triangular
piece of cartillage of pinna and points to
the nerve which lies 1 cm deep .
Page 76
77. INNER EAR
INNER EAR exists within the temporal
bone (petrious portion).
• It is a complex structure. It is located in a
bony cavity called the BONY LABYRINTH
(“maze”).
• It is filled with a fluid called PERILYMPH,
which is similar to CSF.
79. Inner Ear
• Within the bony labyrinth is the MEMBRANOUS
LABYRINTH, filled with ENDOLYMPH.
• One of the membranous structures is the
COCHLEA (“snail shell”). This is responsible for
hearing.
• The other structure is responsible for balance
and consists of three parts:
– Semicircular Canals
– Utricle
– Saccule
81. Inner Ear
Instead of drawing the cochlea curled up,
I’ve drawn it laying out straight.
82. Inner Ear: Cochlea
• Inside the cochlea are special neurons
called HAIR CELLS; their axons form CN
VIII.
• The stapes is attached to the OVAL
WINDOW, and vibrations cause the
perilymph to vibrate; the hair cells here
transmit this vibration.
• Therefore the HAIR CELLS in this region
are receptors for HEARING.
84. Choclea
• Low frequencies (like the longer strings of
a piano) cause a response in the tip of the
cochlea.
• High frequencies cause a response at the
larger end of the cochlea.
85. • The hair cells are connected to CN VIII,
the VESTIBULAR COCHLEAR NERVE,
which takes the signals to the brain.
• Therefore, the cochlea is where the
hearing receptors are located, so the
cochlea is responsible for all of the
hearing of sounds.
• However, the ear does more than just
hear; it is also responsible for balance and
equilibrium.
86. VESTIBULAR SYSTEM
• This system regulates balance.
• It is also within the inner ear.
• SEMI-CIRCULAR CANALS (Three of
them, all in different planes) determine
movement in three planes.
• Within each semi-circular canal is
endolymph and hair cells, which connect
to nerves that go to the cerebellum.
87. • When you move in one direction, like
sliding across the room, the fluid sloshes
like a cup of coffee, and it makes the hair
cells move.
88. Utricle and Saccule
•
•
•
•
•
•
Attached to the semi-circular canals are two joined
structures called the UTRICLE and the SACCULE.
These also contain HAIR CELLS and ENDOLYMPH.
Within the endolymph here are OTOLITHS (“ear rocks”)
which are calcium deposits.
When you stand perfectly upright, these otoliths fall
directly down and bend the HAIR CELLS (a special type
of neuron) on the lower cells. When you tip your head to
the side, they will stimulate the hairs on that side.
The otoliths stimulate the hair cells to tell you what
position your head is in and give you a sense of
equilibrium.
Therefore, the HAIR CELLS in this region are receptors
for equillibrium and the OTOLITHS are an essential
component of this process.
91. Ear Problems
• Inflammation of the semi-circular canals
give you a sense of motion when you’re
not moving = VERTIGO (dizziness) or
LABYRINTHITIS.
• This can be debilitating.
• Sometimes only one canal is affected, so
you only get dizzy if you turn your head
one way.
