in this ppt you will be able to know more about the anatomical structure of the ear and its parts .

1. Dr. Hoda Hassan
Ass. prof. of anatomy & embryology
(2nd year) – (Academic year 2020-2021)

2. •Anatomy of the ear
External ear
Middle ear
•Facial nerve
•Vestibulo-cochlear nerve

4. • The ear is subdivided into: external, middle and internal ear.
• It lie within the temporal bone on the lateral aspect of the skull.
• Each ear is a distance receptor for complex waves of sound.
• It also contains the receptors for hearing and balance.

5. • The external ear has an
auricle, an external
auditory meatus and ear
drum.
THE EXTERNAL EAR

6. Has a characteristic shape
collects air vibrations
consists of a thin plate of yellow
elastic cartilage covered by skin.
(except lobule devoid of cartilage)
Parts: helix, antihelix, concha,
tragus, antitragus, intertragic
notch and lobule
The auricle

7. Muscles: Numerous intrinsic and
extrinsic muscles are associated with
the auricle:
the intrinsic muscles pass between
the cartilaginous parts of the auricle
such as helicis major and minor,
tragicus, antitragicus, transversus
auriculae and obliquus auriculae;
the extrinsic muscles, the anterior,
superior, and posterior auricular
muscles, pass from the scalp or skull
to the auricle and may also play a
role in positioning of the auricle.
The auricle

8. Nerve supply:
• Motor by facial nerve
• Sensory by auriculotemporal,
lesser occipital, great
auricular and auricular branch
of vagus nerves
The auricle

9. • Deeper parts (root) of the auricle are
supplied by branches from the facial nerve
[VII] and the vagus nerve [X].

10. Arterial supply:
• Superficial temporal a
• Posterior auricular a

11. is a curved tube conducts sound waves
from the auricle to the tympanic
membrane.
the outer third is elastic cartilage and
directed upward and backward,
the inner two thirds is bone and
directed downward and forwards
The meatus is lined by skin, and its outer
third is provided with hairs and
sebaceous and ceruminous glands. The
latter are modified sweat glands that
secrete a yellowish brown wax. The hairs
and the wax provide a sticky barrier that
prevents the entrance of foreign bodies.
The external auditory meatus

12. Sensory nerve supply of the lining skin
is derived from the auriculotemporal
nerve and the auricular branch of the
vagus nerve.
The external auditory meatus

13. Separate the external auditory meatus from middle ear cavity
Lies obliquely, downward, forward and laterally
Semi translucent membrane (skin, fibrous tissue and mucous membrane)
EAR DRUM (tympanic membrane)

14. Parts: Pars tensa (all parts contain fibrous tissue) except upper part which is
known as Pars flaccida
EAR DRUM (tympanic membrane)

15. Features:
Ant. and post. malleolar folds
separate Pars tensa and flaccida
Handle of maleus
Con of light (ant inf quadrant)
EAR DRUM (tympanic membrane)

16. Sensory nerve supply
The lining skin is derived from the auriculotemporal nerve and the auricular
branch of the vagus nerve.
Inner surface supplied by tympanic branch of glossopharyngeal n.
EAR DRUM

17. MIDDLE EAR

18. The tympanic cavity
is an irregular,
laterally compressed
space
in the petrous part of the
temporal bone.
lined with mucous
membrane
The cavity is bounded
laterally by the tympanic
membrane and medially
by the lateral wall of the
internal ear.
Middle Ear

19. The space within the
middle ear can be
subdivided into:
1.tympanic cavity
proper, opposite the
tympanic membrane,
2.epitympanic recess
above the level of
the membrane.
Middle Ear

20. Middle Ear
Boundaries of tympanic cavity:
1. ROOF
2. FLOOR
3. Lateral Wall
4. Medial wall
5. Anterior wall
6. Posterior wall
Roof
Floor
Ant. wall
post.
wall lateral wall
Medial wall

21. Middle Ear
ROOF:
The roof of the middle ear cavity is formed by the tegmen
tympani.
It separates the middle ear cavity from the dura of the middle
cranial fossa and temporal lobe of cerebrum.

22. Middle Ear
Floor (jugular wall):
The jugular wall of the
middle ear consists of
a thin layer of bone
that separates it from
the internal jugular
vein. (IJV).
At the junction of the
floor and the medial
wall there is a small
opening which allows
the entry of tympanic
branch of
glossopharyngeal
nerve to pass into the
middle ear.
Floor
IJV
Anterior
Posterior
Medial wall

23. Middle Ear
Lateral Wall:
is partly bony and partly membranous. It consists of the tympanic
membrane & bony lateral wall of the epitympanic recess

24. Middle Ear
Posterior Wall: from above downward
Aditus leading to the mastoid antrum
Pyramid (origin of stapedius muscle)
Opening of chorda tympani nerve
Vertical canal of facial nerve medial to pyramid

25. Middle Ear
Medial Wall:
1. Promontory produced by the 1st turn of the cochlea, Associated with the mucous
membrane covering the promontory is a plexus of nerves (the tympanic plexus) and
branches from the internal carotid plexus.
2. Oval window: posterior superior to the promontory
3. Round window: posterior inferior to the promontory;
4. prominence of horizontal part of facial canal, posterior and superior to the oval
window
5. prominence of lateral semicircular canal just above and posterior to the prominence
of facial canal

26. Middle Ear
Anterior Wall:
1. a smaller opening for the canal containing the tensor tympani muscle.
2. Opening of Pharyngotympanic tube into the middle ear;
3. The lower part consists of a thin plate of bone that separates the tympanic cavity from
the internal carotid artery. This plate is pierced by sympathetic caroticotympanic
nerves and the tympanic branches of internal carotid artery
4. The foramen for the exit of the chorda tympani nerve

27. Middle Ear
Communications:
It communicates posteriorly with the mastoid antrum and with the mastoid
air cells.
Anteriorly it communicates with the nasopharynx via the pharyngotympanic
tube.

28. Contents of tympanic cavity:
1. Air
2. Auditory ossicles
3. Muscles
4. Nerves

29. Contents of tympanic cavity:
1. Auditory ossicles
Three small bones: malleus,
incus and stapes,
They form an articulated chain
connecting the lateral and
medial walls of the cavity,
Transmit the vibrations of the
tympanic membrane across
the cavity to the inner ear.
malleus incus
stapes

30. malleus incus
stapes
Malleus (head, neck & handle)
Handle attached to ear drum
and receive ins. Of tensor tympani
Head articulate with incus
Incus (body & 2 processes)
Body articulate with malleus
Long process articulate with head of
stapes
Stapes (head, neck, 2 limbs & foot)
Head articulate with incus
Neck insertion of stapedius muscle
Foot close the oval window of internal ear

31. 2. Muscles:
Tensor tympani
O:Cartilaginous part of pharyngotympanic
tube, greater wing of sphenoid, its own
bony canal
I: Upper part of handle of malleus
NS: Branch from nerve to medial
pterygoid (mandibular nerve [V3])
AC: Contraction pulls handle of malleus
medially, tensing tympanic membrane to
reduce the force of vibrations in response
to loud noises
Stapedius
O: Attached to inside of pyramidal
eminence
I: Neck of stapes
NS: nerve to stapedius (Branch of facial
nerve [VII])
AC: Contraction, usually in response to
loud noises, pulls the stapes posteriorly
and prevents excessive oscillation

32. 3. Nerves
1. Tympanic plexus
2. Chorda tympani nerve
3. Facial nerve

33. Nerves
1. Tympanic plexus
Site: on the promontary
Formation: tympanic branch
of glossopharyngeal n. and
caroticotympanic branch of
plexus around ICA
Branches: tympanic cavity,
eustachian tube & mastoid
air cells
&Lesser sup. petrosal nerve
that supply parotid gland

34. Nerves
2. Chorda tympani nerve
Fibers: parasympathetic and
taste fibers
Origin: facial nerve in the
vertical part of facial canal
Course: enter the middle ear
through canaliculus in the post.
Wall
then pass through tympanic
cavity and leave the ear through
the squamotympanic fissure
End by joining the lingual nerve
Branches:
parasympathetic supply for
submandibular and sublingual
salivary glands
Taste sensation for ant. 2/3 of
tongue

35. Facial nerve
(CN VII)

36. Facial nerve
a.Functions: mixed (motor, sensory & parasympathetic)
b.Deep origin: pons
c.Components :
1. facial n. proper Motor
2. nervous intermedius parasympathetic and taste

37. Facial nerve
d. Course and relations:
Intrapetrous course
•It enters internal auditory meatus
• Runs in a bony canal in the petrous part of temporal bone called facial canal
• pass backward in the horizontal part of facial canal
• pass downward in the vertical part of facial canal
•to reach the stylomastoid foramen & leave the cranial cavity

38. Facial nerve
Extracranial course
•Turn forward making a curve
around the styloid process
•It enters the substance of
parotid gland and lies superficial
•Ends by dividing into 5 terminal
branches

39. Facial nerve
I. Branches of intrapetrous part:
1.Greater superficial petrosal n: (parasympathetic)------sphenopalatine ganglion
that supply mucous glands of palate, nose, nasopharfynx & lacrimal gland
2.Chorda tympani n: (parasympathetic)----submandibular ganglion and supply
submandibular and sublingual salivary glands
(& taste) -------- ant. 2/3 of tongue
3. Nerve to stapedius m (inside the middle ear)

40. Facial nerve
II. Branches of extracranial part before parotid gland:
1. N. to post. Belly of digastric
2. Post. Auricular n
II. Terminal Branches inside parotid gland:
Temporal, zygomatic, buccal, marginal mandibular and cervical
N. to post.
Belly of digastric
Post.
Auricular n

41. • Although facial nerve is mainly motor, there are some
cutaneous fibers from the facial nerve which accompany
the auricular branch of the vagus and which probably
innervate the skin in the conchal depression (Deep parts
(root) of the auricle).

42. Vestibulo-
cochlear nerve
(CN VIII)

43. Function: Vestibulo-cochlear nerve (CN VIII) carried
special afferent fibers (special sensation) for hearing
and balance
Parts: consists of two divisions:
• a vestibular component for balance;
• a cochlear component for hearing.
Vestibulo-cochlear nerve

44. I. Cochlear nerve:
is one of the two divisions of the vestibulocochlear nerve (CN VIII).
The cochlear nerve arises from the organ of Corti, which lies in the cochlea of
the inner ear. The receptor cells (hair cells) in the organ of Corti receive the
primary stimuli, the information is then transmitted to pseudounipolar neurons
located in the spiral ganglion, which lies in the modiolus (center) of the
cochlea. The axons of these neurons form cochlear nerve.
Vestibulo-cochlear nerve

45. Vestibulo-cochlear nerve
II. Vestibular nerve:
arises from the receptors of
the maculae of utricle and
saccule, and from the
receptors from the ampullary
crest of the membranous
labyrinth.
The axons arising from the
neurons in the vestibular
ganglion form the vestibular
nerve.

46. Vestibulo-cochlear nerve
Cochlear and vestibular
nerves enters the internal
acoustic meatus where
they joins forming
the vestibulo-cochlear
nerve.

47. Vestibulo-cochlear nerve
The vestibulo-cochlear
nerve then travels through
the internal acoustic opening
to the posterior cranial
fossa, then enters the
brainstem in the
cerebellopontine angle along
with the facial nerve (CN
VII).

48. •Anatomy of the ear
External ear
Middle ear
•CN VII (Facial nerve)
•Vestibulo-cochlear nerve