Auditory System

Question 1

The central auditory pathway is a complex pathway with some ascending inputs _____ the midline ____ _____.

Answer 1

The central auditory pathway is a complex pathway with some ascending inputs crossing the midline several times.

Question 2

Central auditory system pathway:

It starts with ____ ____ _____ dendrites endings on the auditory hair cells of the _____.

The somas of these neurons are located in the ___ _____within the ____of the cochlea

Answer 2

Central auditory system pathway:

It starts with primary sensory afferent dendrites endings on the auditory hair cells of the cochlea.

The somas of these neurons are located in the spiral ganglia within the modiolus of the cochlea

Question 3

central auditory system pathway:

______nerves also have axons that synapse on the auditory hair cells,

Answer 3

Central auditory system pathway:

Efferent nerves also have axons that synapse on the auditory hair cells,

Question 4

Central auditory system pathway:

These fibers first synapse in the ____or ____ _____ ____located in the _____end of the medulla adjacent to the base of the _____cerebellar peduncle.

Answer 4

Central auditory system pathway:

These fibers synapse in the dorsal or ventral cochlear nuclei located in the rostral end of the medulla adjacent to the base of the inferior cerebellar peduncle.

Question 5

The cochlear nuclei project _____ to a series of anatomical nuclei/tracts that are considered _____ in function

Answer 5

The cochlear nuclei project bilaterally to a series of anatomical nuclei/tracts that are considered auditory in function

Question 6

central auditory pathway

Beginning with the ____ _____cells in the organ of Corti, the entire auditory pathway is ________ organized.

The apex of the organ of corti responds to ____ frequency sounds, while the base responds to _____ frequency sounds.

Answer 6

central auditory pathway

Beginning with the sensory hair cells in the organ of Corti, the entire auditory pathway is tonotopically organized.

The apex of the organ of corti responds to low frequency sounds, while the base responds to high frequency sounds.

Question 7

Central auditory pathway

• Nerve impulses pass through at least ___ neurons from receptor to cerebral cortex: *
• 1st neuron: ____ _____
• 2nd neuron: anterior and posterior ______ ____
• 3rd neuron: ______ _____
• 4th neuron: thalamus (____ ____ _____)

Answer 7

central auditory pathway

Nerve impulses pass through at least 4 neurons from receptor to cerebral cortex: *

• 1st neuron: spiral ganglion
• 2nd neuron: anterior and posterior cochlear nuclei
• 3rd neuron: inferior colliculus
• 4th neuron: thalamus (medial geniculate nucleus)

Question 8

Auditory pathways have _____representation (input from ____ ears reaches auditory cortex of each ____ _____)

Answer 8

Auditory pathways have bilateral representation (input from both ears reaches auditory cortex of each cerebral hemisphere)

Question 9

• Cochlear nerve fibers synapse with 2nd order neurons in anterior (ventral) and posterior (dorsal) ____ _____
• The cochlear nuclei are located on lateral and posterior surfaces of _______ ____ (inferior cerebellar peduncle), respectively, at pontomedullary junction)

Answer 9

• Cochlear nerve fibers synapse with 2nd order neurons in anterior (ventral) and posterior (dorsal) cochlear nuclei
• The cochlear nuclei are located on lateral and posterior surfaces of restiform body (inferior cerebellar peduncle), respectively, at pontomedullary junction)

Question 10

• Fibers from posterior cochlear nucleus and some from anterior cochlear nucleus form _____ _____ _____
• These axons pass posterior to restiform body, ______ and ascend to ______inferior colliculus via_____ _____

Answer 10

• Fibers from posterior cochlear nucleus and some from anterior cochlear nucleus form posterior acoustic stria
• These axons pass posterior to restiform body, decussate and ascend to contralateral inferior colliculus via lateral lemniscus

Question 11

•Most fibers from ____ ____ _____ pass anterior to restiform body and terminate in ipsilateral and contralateral ____ ____ _____(fibers crossing midline to end in contralateral inferior olivary nucleus form a fiber bundle known as ____ ____)

Answer 11

•Most fibers from anterior cochlear nucleus pass anterior to restiform body and terminate in ipsilateral and contralateral superior olivary nucleus (fibers crossing midline to end in contralateral inferior olivary nucleus form a fiber bundle known as trapezoid body)

Question 12

What is another name for the restiform body?

Answer 12

inferior cerebellar peduncle

Question 13

• Superior olivary nucleus is located in _____ part of _____ of caudal ____
• It receives fibers from _____ and ______ anterior cochlear nuclei
• Gives rise to fibers that ascend largely in _____ _____ _____
• Superior olivary nucleus plays important role in_____ __ ______ in space

Answer 13

• Superior olivary nucleus is located in anterior part of tegmentum of caudal pons
• It receives fibers from ipsilateral and contralateral anterior cochlear nuclei
• Gives rise to fibers that ascend largely in ipsilateral lateral lemniscus
• Superior olivary nucleus plays important role in localization of sounds in space

Question 14

Fibers of lateral lemniscus terminate in ____ _____

Answer 14

Fibers of lateral lemniscus terminate in inferior colliculus

Question 15

Fibers from inferior colliculus ascend along lateral surface of midbrain in _____ of _____ ___, and terminate in _____ ____ ____ of thalamus

Answer 15

Fibers from inferior colliculus ascend along lateral surface of midbrain in brachium of inferior colliculus, and terminate in medial geniculate nucleus of thalamus

Question 16

Fibers from medial geniculate nucleus form ____ ______

Pass inferior to _____ _____ (sublentiform limb of internal capsule)

Terminate in ____ ____ _____

Answer 16

Fibers from medial geniculate nucleus form auditory radiation

Pass inferior to lentiform nucleus (sublentiform limb of internal capsule)

Terminate in primary auditory cortex

Question 17

Primary auditory cortex = ______temporal gyri (Brodmann’s areas 41 and 42); _____surface of temporal lobe (floor of lateral fissure)

Answer 17

Primary auditory cortex = transverse temporal gyri (Brodmann’s areas 41 and 42); superior surface of temporal lobe (floor of lateral fissure)

Question 18

Nucleus of trapezoid body helps ____ ____ _____ in _________sounds in space.

Answer 18

Nucleus of trapezoid body helps superior olivary nucleus in localizing sounds in space.

Question 19

•Head/eye turning reflex = ____ _____

Answer 19

•Head/eye turning reflex - corpora quadrigemina

Question 20

What is the middle ear reflex used for?

Answer 20

dampening of loud sounds by affected ear ossicles

Question 21

Middle ear reflex pathway

1. cochlear nuclei
2. ______ olivary nucleus
3. motor nucleus of _____ and motor nucleus of ______
4. ______ m and ______ m

Answer 21

middle ear reflex pathway

1. cochlear nuclei
2. superior olivary nucleus
3. motor nucleus of V and motor nucleus of VII
4. tensor tympani m and stapedius m

Question 22

Cortical Lesion:

• Sound ______ is impaired.
• Sound ______ can be appreciated.

Answer 22

Cortical Lesion:

• Sound LOCALIZATION is impaired.
• Sound INTENSITY can be appreciated.

Question 23

Auditory pathway _______sound by time differences.

Answer 23

Auditory pathway LOCALIZES sound by time differences.

Question 24

The medulla receives ______ and directional information.

Answer 24

The medulla receives INTENSITY and directional information.

Question 25

Once above the cochlear nu. information is \_\_\_\_\_\_

Answer 25

Once above the cochlear nu. information is **_BILATERAL_**.

Question 26

Peripheral nerve damage affects the _____ ear.

Answer 26

Peripheral nerve damage affects the **_same_** ear.

Question 27

•Conduction deafness (conduction hearing loss): results from any interference with _____ of sound waves through \_\_\_\_\_or ____ ear (ex. serous otitis media, otosclerosis)\*

Answer 27

•Conduction deafness (conduction hearing loss): results from any interference with **_passage_** of sound waves through **_external_** or **_middle_** ear (ex. serous otitis media, otosclerosis)\*

Question 28

•Nerve deafness (sensorineural hearing loss): results from damage to ____ cells in _____ organ or to _____ nerve (ex. ototoxic drugs, acoustic neuroma)\*

Answer 28

•Nerve deafness (sensorineural hearing loss): results from damage to **_receptor_** cells in **_spiral_** organ or to **_cochlear_** nerve (ex. ototoxic drugs, acoustic neuroma)\*

Question 29

•Unilateral lesions to auditory cortex or auditory pathways distal to cochlear nuclei cause virtually\_\_\_\_\_loss of hearing - they produce subtle hearing impairments (may impair ability to localize direction and distance of sounds)

Answer 29

•Unilateral lesions to auditory cortex or auditory pathways distal to cochlear nuclei cause virtually **_no_** loss of hearing - they produce subtle hearing impairments (may impair ability to localize direction and distance of sounds)