14.1 External and Middle Ear

Question 1

Locate the following aspects of the external ear: 
A.	Helix
B.	Antihelix
C.	Concha
D.	Tragus
E.	Antitragus
F.	Earlobe
G.	External auditory canal

Answer 1

-

Question 2

What is the innervation for the auricle?

Answer 2

the auricle is innervated primarily from the great auricular and lesser occipital (C2-C3) and the auriculotemporal (CN V3), with minor contributions from the facial (CN VII) and vagus (CN X).

Question 3

Describe the function of the ceruminous and sebaceous glands in the external acoustic meatus.

Answer 3

-Ceruminous and sebaceous glands produce cerumen (earwax) that acts to protect the tympanic membrane from bacteria/fungal infection.

Question 4

What innervates the external acoustic meatus?

Answer 4

shared by the auriculotemporal and vagus nerves.

Question 5

Describe the covering and innervation of the external and internal surface of the tympanic membrane.

Answer 5

The membrane is covered with skin externally (innervated by CN X and auriculotemporal branch of CN V3) and mucus membrane internally (innervated by tympanic branch of CN IX).

Question 6

Describe cauliflower ear.

Answer 6

fibrous build-up of internal ear tissues from repeated trauma and auricular hematoma.

Question 7

Describe otitis externa

Answer 7

“swimmer’s ear” -infection of the external auditory meatus.

Question 8

Identify the malleus (and its handle), incus, and stapes

Answer 8

-

Question 9

Identify the chorda tympani nerve.
What CN does this branch from?
What is its function?

Answer 9

• Branch of CN VII (facial)

- Taste on anterior 2/3 of tongue

Question 10

Identify the facial nerve and describe its course.

Answer 10

passes into the temporal bone through the internal acoustic meatus, passing though the facial canal and exiting the skull via the stylomastoid foramen.

Question 11

Identify the tensor tympani. Describe its attachments, innervation, and function

Answer 11

• originating from the pharyngotympanic tube, greater wing of sphenoid and petrous part of temporal bone –Inserting into the handle of the malleus.
• Supplied by CN V3
• works to reduce the amplitude of its oscillations, preventing damage from loud sounds.

Question 12

Identify the mastoid antrum

Answer 12

Posterior to the cavity.

Question 13

Identify the oval window as well as the stapedius muscle and promontory.
Describe the attachment, innervation, and function of the stapedius.
Describe the promontory.

Answer 13

• Stapedius: coming from the posterior wall at the pyramidal eminence, inserting into the neck of the stapes. I
• Innervated by CN VII
• Fxn: tilts the stapes in the oval window reducing the oscillatory range while preventing excess movement.

Promontory: the projection outward of the first turn of the cochlea.