34: Auditory Pathway And Vestibular System

Question 1

Where does the cochlear nerve enter the brainstem at?

Answer 1

Cerebellopontine angle

Question 2

Central cochlear nucleus sends fibers where?

Answer 2

Inferior colliculus

Question 3

What type of input does the medial superior olivary nucleus receive?

Answer 3

Excitatory input (EAAs)

Question 4

Olivocochlear efferents function

Answer 4

Decrease basilar membrane motion -> protect hair cells from damage from loud sounds

Question 5

Origin of olivocochlear efferents

Answer 5

Superior olivary complex

Question 6

Purpose of middle ear muscle motor neurons

Answer 6

Decrease transmission of sound at low frequencies to prevent hair cell damage + low frequency masking

Question 7

What nerves to the ear are implicated in tinnitus

Answer 7

Middle ear muscle motor neurons (tensor tympani and stapedius)

Question 8

Three sources of autonomic sympathetic innervation to the inner ear

Answer 8

1. CN 8
2. Caroticotympanic nerve (from superior cervical ganglion)
3. Acoustic nerve

Question 9

What does the caroticotympanic nerve innervate?

Answer 9

Mucous glands and blood vessels of the TM

Question 10

What does the acoustic nerve innervate?

Answer 10

Blood vessels of inner ear to regulate vascular tone to cochlea

Question 11

Cochlea and auditory nuclei of pons and medulla blood supply

Answer 11

Basilar A

Question 12

Inner ear and cochlear nucleus blood supply

Answer 12

Internal auditory A (labyrinthine A, branch of the AICA)

Question 13

Occlusion of the internal auditory A

Answer 13

Monaural hearing loss + ipsilateral facial paralysis with inability to look towards side of lesion

Question 14

Superior olivary complex and lateral lemniscus blood supply

Answer 14

Short circumferential branches of basilar A

Question 15

Inferior colliculus blood supply (2)

Answer 15

Superior cerebellar A, quadrigeminal A

Question 16

Medial geniculate bodies blood supply

Answer 16

Thalamogeniculate A’s

Question 17

Primary auditory and associating auditory cortices blood supply

Answer 17

M2 of MCA

Question 18

Three types of hearing loss and what is damaged in them

Answer 18

Central: central pathway
Sensorineural: cochlea, root of CN 8, or hair cells
Conductive: obstruction of sound to TM

Question 19

What can cause sensorineural hearing loss?

Answer 19

Antibiotics, tumors, repeated loud noise, old age, unknown etiologies

Question 20

Is sensorineural hearing loss usually ipsilateral or bilateral?

Answer 20

Ispilateral

Question 21

Is central hearing loss usually ipsilateral or bilateral?

Answer 21

Bilateral

Question 22

Which end of the cochlea is more susceptible to damage?

Answer 22

Basal end (higher frequency)

Question 23

Cochlear prosthesis

Answer 23

Multiple-electrode array threaded through cochlea to stimulate surviving nerve fibers

Question 24

What can cause conductive hearing loss?

Answer 24

Damage to pinna, excess ear wax, damage to TM

Question 25

Three semicircular canals and what motion they detect

Answer 25

Anterior: rotation forwards (falling forward)
Posterior: rotation backwards
Horizontal: rotation in horizontal plane (spinning around)

Question 26

Utricle and saccule: motions they detect

Answer 26

Utricle: linear acceleration forward and backward
Saccule: linear acceleration up and down