Auditory tracts

Question 1

Sensorineural deafness

Answer 1

Damage to the cochlea, the cochlear part of CNVIII (IL), or to the cochlear nuclei

Question 2

Central deafness

Answer 2

Damage to central pathways

Question 3

Conduction deafness

Answer 3

Obstructed, altered, transformation of sound to the TM or through ossicles

Question 4

Basilar a. …

Answer 4

Cochlea and the auditory nuclei of the pons and medulla

Question 5

Internal auditory (labyrinthine a.)

Answer 5

• Branch of AICA

- Supplies inner ear and cochlear nuclei

Question 6

Consequences of AICA occlusion?

Answer 6

• May also damage emerging fibers of CN VII and pontine gaze center
• Results in monaural hearing loss, IL facial paralysis and inability to look toward side of lesion

Question 7

Short circumferential branches of basilar a.

Answer 7

Superior olivary complex and lateral lemniscus

Question 8

Superior cerebellar and quadrigeminal aa.

Answer 8

Inferior colliculus

Question 9

Thalamogeniculate aa.

Answer 9

Medial geniculate bodies

Question 10

M2 of MCA

Answer 10

Primary auditory and association cortices

Question 11

General auditory pathway

Answer 11

Primary afferent is CN VIII (cochlear part)
Enters brainstem at PMJ (ascending and descending branches)
Synapses in cochlear nuclei

Question 12

Ascending bundle synapses?

Answer 12

@ anterior subdivision of ventral cochlear nucleus

Question 13

Descending bundle synapses?

Answer 13

@ posterior subdivision of ventral cochlear nucleus AND in dorsal cochlear nucleus

Question 14

Function of dorsal cochlear nuclei?

Answer 14

Identifying sound source elevation and identifying complex spectral characteristics of sounds

Question 15

Function of ventral cochlear nuclei?

Answer 15

Horizontal localization of sound

Question 16

Monaural Tract

Answer 16

Dorsal cochlear nucleus - crosses to CL side via dorsal acoustic stria - ascends in lateral lemniscus - inferior colliculus – MGN (via brachium of inferior colliculus) - Primary auditory cortex (layer IV)

Question 17

Binaural Tract

Answer 17

Ventral cochlear nucleus - projects bilaterally through trapezoid body - Superior olivary nucleus (medial/lateral olivary nucleus) - Ascend in lateral lemniscus - Inferior Colliculus - MGN (via brachium of inferior colliculus) - Primary auditory cortex (layer IV)