10. Ear Anatomy (Keim)

Question 1

What nerves innervate the tympanic membrane?

Answer 1

External surface: Auriculotemporal nerve and Auricular branch of the vagus.

Internal surface: Glossopharyngeal (CN IX)

Question 2

What would be affected in an erosion through the medial wall of the middle ear?

Answer 2

The inner ear, the oval and round windows, the promontory of the labyrinthine wall, and the nerve plexus thereof (tympanic and lesser petrosal nerves).

Question 3

Greater and lesser petrosal nerves carry what type of nerve fibers?

Answer 3

Parasympathetic (general visceral efferent) fibers.

Question 4

What cranial nerve does the tympanic nerve come off of?

Answer 4

The glossopharyngeal (CN IX)

Question 5

Which portion of the tympanic membrane is more vascular?

Answer 5

The superior portion.

Question 6

What is a myringotomy, and where is it performed?

Answer 6

Myringotomy: lesion to open up the eardrum. Made in the posterior inferior quadrant to avoid vasculature.

Question 7

The tympanic plexus primarily contains fibers from which cranial nerve?

Answer 7

Glossopharyngeal, via the tympanic branch.

Question 8

Answer 8

Question 9

What is the blood supply to the auricle of the ear?

Answer 9

Posterior auricular A and superficial temporal A.

Question 10

What would be affected in an erosion through the posterior wall of the middle ear?

Answer 10

Mastoid antrum (containing mastoid air cells) and facial canal (containing facial nerve).

Question 11

Where are the heads of the incus and malleus found?

Answer 11

In the epitympanic recess.

Question 12

What would be affected in an erosion through the anterior wall of the middle ear?

Answer 12

Internal carotid artery, opening for the pharyngotympanic tube, and the canal for the tensor tympani.

Question 13

What would be affected in an erosion through the lateral wall of the middle ear?

Answer 13

Tympanic membrane and external ear.

Question 14

What are the respective functions of the greater and lesser petrosal nerves?

Answer 14

Greater petrosal: parasympathetics to the eye from facial N.

Lesser petrosal: parasympathetics to the parotid gland from glossopharyngeal N.

Question 15

Answer 15

Question 16

List the nerves that innervate the represented parts of the auricle of the ear.

Answer 16

Question 17

What would be affected in an erosion through the roof of the middle ear?

Answer 17

The tegmen tympani (bone) and the dura of the middle cranial fossa.

Question 18

What is the bony labyrinth filled with?

What is the membranous labyrinth filled with?

Answer 18

Bony labyrinth: perilymph.

Membranous labyrinth: endolymph.

Question 19

What nerve gives rise to the greater petrosal nerve?

Answer 19

Facial nerve.

Question 20

What would be affected in an erosion through the floor of the middle ear?

Answer 20

Bulb of the internal jugular vein.

Question 21

Which of these spaces contain endolymph, and which contain perilymph?

Answer 21

The scala vestibuli and the scala tympani are filled with perilymph. The cochlear duct is filled with endolymph.

Question 22

What nerve gives rise to the lesser petrosal nerve?

Answer 22

The tympanic nerve - a branch of the glossopharyngeal nerve.

Question 23

Answer 23

Question 24

Answer 24

Note that “malleolus” is actually “malleus.” This slide has a typo.

Question 25

Which is more anterior, the cochlea or the vestibular apparatus?

Answer 25

The cochlea.