Chapter 11: The Auditory Nerve & Central Auditory Pathways

Question 1

Internal Auditory Canal (IAC)

Answer 1

-Begins at the cochlear modiolus and ends at the base of the brain

Question 2

What passes through the IAC?

Answer 2

-Vestibulocochlear nerve
-Facial nerve
-Internal auditroy artery

Question 3

Auditory Nerve Fiber Organization

Answer 3

-Basal, high frequencies are on the outer portion
-Apical, low frequencies are on the inner portion

Question 4

Cerebellopontine Angle (CPA)

Answer 4

-Place on brain stem where the cerebellum, medulla, and pons join together
-Point where the auditory and vestibular nerves separate

Question 5

Decussations

Answer 5

-Crossover points within the brain that unite symmetrical portions

Question 6

Commissures

Answer 6

-Nerve fiber bundles that unite similar structures on both sides of the brain

Question 7

Ipsilateral

Answer 7

-Same side

Question 8

Contralateral

Answer 8

-Opposite side

Question 9

Cochlear Nucleus

Answer 9

-Receives information from the auditory nerve fibers as they enter the CPA

Question 10

Trapezoid Body

Answer 10

-Located in the pons
-Represents the start of the bilateral representation of a signal presented to one ear
-Routes signal to superior olivary complex, contralateral superior olivary complex, and lateral lemniscus

Question 11

First decussation point of the auditory system

Answer 11

trapezoid body

Question 12

Superior Olivary Complex (SOC)

Answer 12

-Receives input from cochlear nuclei
-Allows for sound localization
-Controls reflex activity of stapedius and tensor tympani
-Routes signal to inferior colliculus through the lateral lemniscus

Question 13

Lateral Lemniscus

Answer 13

-Routes signal from the SOCs to the inferior colliculus
-Receives afferent stimulation from both SOCs

Question 14

Medial Geniculate Body (MGB)

Answer 14

-Located in thalamus
-Last subcortical relay station for auditory impulses
-Ventral part is responsible for auditory information
-Routes signal to auditory cortex

Question 15

Heschl’s Gyrus (Superior Temporal Gyrus)

Answer 15

-Area of auditory reception located within the temporal lobes on both sides of the cerebral cortex

Question 16

Disorders of the Auditory Nerve Symtomology

Answer 16

-Tinnitus
-High freq SNHL
-Asymmetrical SNHL
-Speech recognition scores that are worse than expected given threshold levels

Question 17

Acoustic Neuromas

Answer 17

-Benign tumors that originate in the internal auditory canal
-The larger the tumor grows, the more likely it is to cause damage as it presses against other nerves and the brain

Question 18

Vestibular Schwannoma

Answer 18

-Another name for an acoustic neuroma as most acoustic neuromas begin in the Schwann cells on the sheath of the vestibular nerve

Question 19

Audiologic Manifestations of Acoustic Neuromas

Answer 19

-unilateral growths
-tinnitus, dizziness, speech recognition difficulties
-progressive unilateral hearing loss

Question 20

Auditory Neuropathy Spectrum Disorder (ANSD)

Answer 20

-Normal outer hair cell function with dyssynchronous firing of the auditory nerve

Question 21

ANSD Audiologic Manifestations

Answer 21

-mild to moderate SNHL
-speech recognition scores disproportionately worse than the degree of measured loss
-doesn’t benefit much from amplification

Question 22

Auditory Processing Disorder (APD)

Answer 22

-Individuals with APD present with difficulty interpreting auditory information without an accompanying hearing loss
-May complain of decreased hearing sensitivity but testing reveals hearing within normal limits
-Acquired (stroke, tumor, ms, head trauma) or congenital

Question 23

Management of APD

Answer 23

-Collaboration of SLP and AUD
-AUD diagnoses and SLP implements therapy and conducts testing to reflect language ability and functional deficits of communication