The Auditory System

Question 1

Contains the neural components of the auditory system.

Answer 1

cochlea

Question 2

Control the distance of movement of the stapes in the oval window.

Answer 2

tensor tympani and stapedius

Question 3

What occurs within the cochlea to transduce sound?

Answer 3

when fluid moving in the scala vestibuli moves, causing Reissner’s membrane to vibrate, causing the tectorial membrane to vibrate, bending the hair cells to cause a neural stimula (interpreted as sound)

Question 4

Modifiers of sound.

Answer 4

outer hair cells

Question 5

Neural component of the cochlea.

Answer 5

organ of corti

Question 6

Detectors of sound.

Answer 6

inner hair cells

Question 7

Scala vestibuli

Answer 7

vestibular membrane such that with the perilymphatic fluid moves it displaces the membrane, causing the organ of corti to be displaced

Question 8

Primary differences between inner and outer hair cells.

Answer 8

Inner hair cells have tons of mitochondrial, Outer hair cells has few mitochondria
Inner hair cells have afferent ending and Outer hair cells have efferent endings to stimulate them to contract

Question 9

_______ _______ contain the actin and myosin: contractile components

Answer 9

Lateral Cisterns

Question 10

What happens when a sound is heard?

Answer 10

A sound wave coming in will cause vibration of tympanic membrane, amplified by inner ear ossicles, which create pressure wave in perilymph in scala vestibuli that vibrate reissner’s membrane to vibrate. This causes organ of corti membrane to vibrate, stimulating hair cells to create an action potential for understanding of sound.

Question 11

Scala tympani

Answer 11

continuous with scala vestibuli, and touches/decompresses at round window

Question 12

Tonotropic organization of the cochlea.

Answer 12

the organ of corti is narrowest at the oval window and widest at the end of the cochlear canal (helicotrema); closer to the oval window is high frequency, by the helicotrema/cochlear duct is low frequency; total length is 35 mm

Question 13

Pathway in the spinal cord through which sound travels.

Answer 13

lateral lemniscus (ventral pathway)

Question 14

Does sound information enter the spinal cord ipsilaterally or contralaterally?

Answer 14

both (will be delayed on contralateral side)

Question 15

Ventral Cochlear Pathway

Answer 15

First order neuron synapse in the ventral cochlear nucleus
Second order neuron will synapse in ipsilateral in superior olivary nucleus and some will synapse to contralateral side
Third order neurons will ascend to inferior colliculus, via pathway called lateral lemniscus

Question 16

In the auditory system, how many neurons are needed at a minimum?

Answer 16

5

Question 17

Dorsal Cochlear Pathway

Answer 17

similar to Ventral except bypasses the superior olivary nucleus

Question 18

Second order neurons in the ventral pathway synapse where?

Answer 18

superior olive

Question 19

Third order neurons of both pathways synapse where?

Answer 19

inferior colliculus

Question 20

Fourth order neurons of both pathways synapse where?

Answer 20

medial geniculate of thalamus

Question 21

Fifth order neurons of both pathways synapse where?

Answer 21

temporal gyrus of Heschi

Question 22

After damage to the vesitbulocochlear nerve, healing can occur. Why?

Answer 22

part of the peripheral nervous system and has a schwann cell coating (can regenerate); this can occur after an acoustic neuroma (schwannoma)

Question 23

What is the significance of neurons synapsing on both sides?

Answer 23

the significance of this is that it allows for a person to localize where the sound is coming from, since you will not be receiving the sound at the same time on each side