The ear is divided into three parts - external, middle, and inner ear. The external ear includes the auricle and external auditory canal. The middle ear, or tympanic cavity, contains the three ossicles (malleus, incus, stapes) and two small muscles (tensor tympani and stapedius). It is separated from the inner ear by the oval and round windows. The complex anatomy of the middle ear, including its walls, spaces, folds, and vascular and neural supply, allow it to efficiently transmit sound vibrations from the outer to inner ear.

1. Anatomy of Ear
DR SAFIKA ZAMAN, PGT, DEPT OF ENT &HEAD NECK SURGERY
VIMS,RKMSP

2. Introduction
 A three-dimensional
appreciation of the
complex temporal bone
anatomy is crucial for the
understanding of both the
pathophysiology and
surgery of the Ear.
 Ear is divided into three
parts – external, middle
and internal.

3. The external Ear
 Auricle: The auricle is formed
from elastic fibrocartilage.
 Auricle is a continuous plate
except for a narrow gap
between the tragus and the
anterior crus of the helix.
 cartilage of the auricle is
connected to the temporal bone
by two extrinsic ligaments. The
anterior ligament And the
posterior ligament.

4. Arterial supply
 Two branches of the
external carotid artery, the
posterior auricular artery
and the superficial
temporal artery, are the
sources of arterial blood
supply to the pinna and
EAC.

5. Innervation of Auricle
 The Auriculo temporal branch of
the trigeminal nerve,
 Greater auricular nerve {a branch
of C3),
 Lesser occipital nerve (ofC2 and
C3 derivation),
 Auricular branch of the Vagus
nerve(Arnold's nerve), and twigs
from the facial nerve.

6. The external auditory canal
 2.4 cm long.
 Lateral 1/3rd is made up of
cartilage, medial 2/3 of bone.
 Have two narrow
constrictions.
 Fissure of Santorini.
 Two sutures lines :
tympanosquamous and
tympanomastoid

7. Cont…
 The external canal is lined with
keratinizing stratified squamous
epithelium
 ceruminous and sebaceous glands
 The arterial supply of the external
meatus is derived from branches of
the external carotid.
 1.The auricular branches of the
superficial temporal artery.
 2 The deep auricular branch of the
first part of the maxillary artery.

8. Innervation of external auditory canal
 The external
auditory canal
receives its
sensory
innervation
from the
trigeminal,
facial,
glossopharyng
eal and vagus
nerves

9. Relationships of the external
auditory canal.

10. The Middle ear cleft
 The middle ear cleft
consists of the
tympanic cavity, the
Eustachian tube and
the mastoid air cell
system.

11. The tympanic membrane
 It is slightly oval in shape.
 Forms an angle of about 55°
with the floor.
 Its longest diameter is 9–10
mm,
 Shortest diameter is 8–9 mm.
 The tympanic annulus,
 The tympanic sulcus.
 The notch of Rivinus

12. The Tympanic membrane
 Pars tensa
 Pars flaccida
 Arrangement of fibres:

13. The tympanic cavity
 The tympanic cavity is traditionally
divided into three compartments:
the epi tympanum (upper), the
mesotympanum (middle) and
hypotympanum (lower).

14. The lateral wall
 The lateral wall of the tympanic cavity is
formed by the bony lateral wall of the
epitympanum superiorly, the tympanic
membrane centrally and the bony lateral
wall
 Two holes are present in the bone of the
medial surface
 The petrotympanic fissure gives passes
to tympanic branch of internal maxillary
artery.
 canal of Huguier: corda leaves the cavity.

15. The Roof
Tegmen tympani:
Cog: which divides the
larger posterior
epitympanic space from
the smaller anterior
epitympanic space, where
residual cholesteatoma
may be left .

16. The floor
 The floor separates the hypo
tympanum from the dome of the
jugular bulb and its thickness can
vary according to the height of the
jugular fossa.
 Occasionally, the floor is deficient.
 inferior tympanic canaliculus,
 that allows the entry of the tympanic
branch of the glossopharyngeal nv.

17. The anterior wall
 The lower third of the anterior
wall consists of a plate of bone
covering the carotid artery.
 This plate, which can be wafer
thin or upto to 3 mm thick,
perforated by the superior and
inferior caroticotympanic nerves
and by tympanic branches of the
internal carotid artery.

18. Cont…
 The middle third of the anterior
wall comprises the tympanic orifice
of the Eustachian tube.
 Just above this is a canal
containing the tensor tympani
muscle.

19. The medial wall
 The medial wall separates the tympanic
cavity from the internal ear
 The promontory is a rounded elevation.
 oval window: This is a nearly kidney-
shaped opening that connects the
tympanic cavity with the vestibule, Its
size on average it is 3.25 mm long and
1.75 mm wide.
 The oval window niche: depression in
between the facial nerve superiorly, and
the prominence of the promontory.

20. Cont…
 The round window niche lies
below and a little behind the
oval window niche
 subiculum: posterior extension
of bony promontory separating
round window from oval
window.
 The ponticulus: leaves the
promontory above the
subiculum and runs to the
pyramid.

21. Cont…
 Sinus tympani:
 The facial nerve canal (or
Fallopian canal) runs above the
promontory and oval window in
an anteroposterior direction.
 processus cochleariformis: a
curved projection of bone,
which houses the tendon of the
tensor tympani

22. The posterior wall
 upper part a large irregular
opening – the aditus and antrum.
 the fossa incudis, lies below the
aditus which houses the short
process of the incus and its
suspensory ligament.
 the pyramid,lies below fossa
incudis houses the stapedius
muscle and tendon,

23. The content of middle ear
 The ear ossicles
 The muscles- tensor tympani and the stapedius.
 The middle ear mucosal folds and spaces.
 Vessels of middle ear.
 Nerves of middle ear.

24. Middle ear ossicles
The malleus, the most lateral of the
ossicles, has a head Manubrium or handle
of malleus, neck, and anterior and lateral
processes.
The anterior ligament of the malleus,
extending from the anterior process,
passes through the petrotympanic fissure
and, with the posterior incudal ligament,
creates the axis of ossicular rotation.

25. The incus
 The incus, the largest of the
three ossicles.
 The incus has a body and
three processes:a long, a
short, and a lenticular.

26. The stapes
 The stapes is the smallest and
most medial of the ossicles.
 footplate sits in the oval
window, surrounded by
 the stapedio vestibular
ligament. The arch of the
stapes, composed of an
anterior and a posterior crus.

27. The muscles of the middle ear
 THE STAPEDIUS
MUSCLE
 The stapedius arises
the pyramid, A slender
tendon emerges from
the apex of the pyramid
and inserts into the
stapes.
 The muscle is supplied
by a small branch of the
facial nerve.

28. The Tensor tympani muscle
 arising from the walls of the bony canal lying above the
Eustachian tube.in middle ear it hooks processus
cochleariformis and insert intothe malleus handle.
 The muscle is supplied from the mandibular nerve.

29. The mucosa of middle ear
 The Mucous Membrane of the Tympanic Cavity is continuous with
that of the pharynx, through the auditory tube.
 It invests the auditory ossicles, and the muscles and nerves
contained in the tympanic cavity; forms the medial layer of the
tympanic membrane, and the lateral layer of the secondary
tympanic membrane, and is reflected into the tympanic antrum
and mastoid cells, which it lines throughout.

30. The mucosa of middle ear
 The middle ear mucosa is
essentially mucus-secreting
respiratory mucosa bearing cilia on
its surface.
 Three distinct mucocilary
 pathways can be identified –
epitympanic,promontorial and
hypotympanic,
 These pathways coalesces at the
tympanic orifice of the Eustachian
tube.

31. Middle ear mucosal folds
 Anatomically and functionally, attic and mesotympanum are
divided by epitympanic diaphragm.
 Epitympanic diaphragm consists of four ligamental folds and two
membranous folds along with the malleus and incus
 Attic and mesotympanum are communicated through small holes
that are present in epitympanic diaphragm— tympanic isthmi.

32. Middle ear mucosal folds
The ligamental folds of epitympanic
diaphragm include the following:
1. Posterior malleolar ligament.
2. Lateral malleolar ligament.
3. Anterior malleolar ligament.
4. Posterior incudal ligament.
The membranous folds of epitympanic
diaphragm include the following:
1. Lateral incudo malleolar fold. 2. Tensor
fold.

33. Middle ear mucosa
Lateral Malleolar Ligament:
It attaches malleus at the junction of
the head and neck and radiates
upward to attach entire bony rim of
notch of Rivinus. Forms prussaks
space.
Lateral Incudomalleolar fold starts
from lateral portion of posterior
incudal fold and continues directly
anteriorly between incus short
process and lateral attic wall up to
the posterior edge of malleus.

34. Middle ear mucosal folds
 Anterior Malleolar Ligament :
This ligament posteriorly attaches the
neck and anterior malleolar process of
malleus to the anterior tympanic spine.
Posterior Incudal Ligament:
Tip of the short process of incus is
firmly fixed to the surrounding bone
laterally and medially by posterior
incudal ligament.

35. Middle ear mucosal folds
 Tensor Fold Tensor fold is variable
anatomic position. It is superiorly a
convex membrane extending medial to
lateral from tensor tympani canal to
lateral part of attic. Posteriorly, it is
attached to the tensor tendon and
cochleariform process, whereas its
anterior attachment is to the roof of
zygoma.

36. Cont..
The posterior malleolar ligament and forms the
medial boundary of posterior pouch of Von
Troeltsch, whereas the lateral boundary is
formed by the tympanic membrane.
Posterior pouch is the main route of ventilation
to Prussak’s space. By its regular contraction,
posterior malleolar ligament encourages air
passage and helps to ventilate Prussak’s space.

37. Middle ear spaces
 Tympanic Isthmus The tympanic isthmus is a narrow elongated
space in the tympanic diaphragm that connects the attic to
mesotympanum. The entire attic is ventilated through the
tympanic isthmus.
 Anterior Tympanic Isthmus The anterior tympanic isthmus is a
very important route for aeration and is situated between the
tensor tympani tendon anteriorly and incudostapedial joint
posteriorly.
 Posterior Tympanic Isthmus The posterior tympanic isthmus is
less important space situated between the short process of incus
and the stapedial muscle.

38. Blood supply of middle ear

39. Nerve of middle ear
Tympanic plexus is formed by the
tympanic nerve, by an anastomotic
branch of the facial nerve, and by
sympathetic branches coming from
the internal carotid plexus,
supplies the mucosa of the middle
ear, the mastoid cells, and the
auditory tube, and gives off the
lesser petrosal nerve to the otic
ganglion.

40. Mastoid ear cell system

41. Relationship of mastoid antrum

42. Anatomy of inner ear
The inner ear is located within
the petrous part of the temporal bone.The
inner ear has two main components – the
bony labyrinth and membranous labyrinth.
Bony labyrinth – consists of a series of
bony cavities within the petrous part of
the temporal bone. It is composed of the
cochlea, vestibule and three semi-circular
canals.
Membranous labyrinth – lies within
the bony labyrinth. It consists of the
cochlear duct, semi-circular ducts, utricle
and the saccule.

43. The vestibule
 The vestibule is the central part of
the bony labyrinth. It is separated
from the middle ear by the oval
window, and communicates
anteriorly with the cochlea and
posteriorly with the semi-circular
canals. Two parts of the
membranous labyrinth;
the saccule and utricle, are located
within the vestibule.

44. cochlea
 The cochlea houses the cochlea duct of
the membranous labyrinth – the auditory
part of the inner ear. It twists upon itself
around a central portion of bone called
the modiolus,
 Scala vestibuli: Located superiorly to the
cochlear duct. As its name suggests, it is
continuous with the vestibule.
 Scala tympani: Located inferiorly to the
cochlear duct. It terminates at the round
window.

45. Semi circular canals
 There are three semi-circular canals; anterior, lateral and
posterior. They contain the semi-circular ducts, which are
responsible for balance (along with the utricle and saccule).
 The canals are situated supero posterior to the vestibule, at right
angles to each other. They have a swelling at one end, known as
the ampulla.

46. Cont…

47. Cochlear Duct
The cochlear duct is located within the bony
scaffolding of the cochlea. It is held in place
by the spiral lamina. The cochlear duct can
be described as having a triangular shape:
 Lateral wall –thickened periosteum,
known as the spiral ligament.
 Roof – Reissner’s membrane.
 Floor – the basilar membrane.

48. Organ of corti
The organ of Corti is composed of
both supporting cells and mechano
sensory hair cells. The arrangement
of mechano sensory cells are into
inner and outer hair cells along rows
. There is a single row of inner hair
cells and three rows of outer hair
cells which are separated by the
supporting cells. The supporting
cells are also named Dieters or
phalangeal cells.

49. Cont….
 The hair cells within the organ of Corti have sterocilia that attach
to the tectorial membrane. Shifts between the tectorial and
basilar membranes move these sterocilia and activate or
deactivate receptors on the hair cell surface.

50. Arterial supply of inner ear
 he labyrinthine artery is the main
supplier of oxygenated blood to
the cochlea and therefore the
organ of Corti. This artery is also
known as the auditory artery or
internal auditory artery. The
labyrinthine artery most commonly
originates from the anterior
inferior cerebellar artery.

51. Internal auditory meatus
The internal auditory meatus provides a
passage through which the CN VIII, CN VII, and
the labyrinthine artery.
It also contains the vestibular ganglion.

52. Thank you