Anatomy of the Auditory System

Question 1

Hardest bone in the human body

Answer 1

Bone of cochlea and vestibular labyrinth

Question 2

Parts of labyrinth (3)

Answer 2

Vestibule, Cochlea, SCC

Question 3

Round window is at which end of the cochlea

Answer 3

Basal

Question 4

Also known as the core of the cochlea, porous bone that allows passage of auditory nerve fibers from the internal auditory meatus to the hair cell synapse

Answer 4

Modiolus

Question 5

Separates cochlear chambers to scala vestibuli, media, tympani

Answer 5

Osseous spiral lamina * Also the attachment of the basilar membrane

Question 6

Area where scalae communicate at the apex of the cochlea

Answer 6

Helicotrema

Question 7

T or F: Widths of spiral lamina and basilar membrane are inversely related

Answer 7

T * Spiral lamina wide at base narrow at apex, Basilar membrane wide at apex narrow at base

Question 8

Bony channel that allows perilymphatic fluid and CSF to communicate in the posterior fossa

Answer 8

Cochlear aqueduct

Question 9

Thickened band of periosteum that serves as medial attachment for the Reissner membrane and gives rise to the tectorial membrane

Answer 9

Spiral Limbus

Question 10

Tectorial membrane is a compliant gelatinous structyre composed of _______fibers.

Answer 10

Collagen II

Question 11

How many rows of cells make up the 1)inner hair cells, 2) outer hair cells

Answer 11

1) one, 2) three

Question 12

This supports the apices of hair cells and forms a barrier from endolymph (which is toxic to hair cells)

Answer 12

Reticular lamina

Question 13

Distinguish perilymph and endolymph based on: 1) composition, 2) location

Answer 13

Perilymph (Low Key) : 1) High Na, Low K, 2) CSF/Serum; Endolymph: Low Na, High K, 2) Intracellular

Question 14

This maintains ionic concentrations of endolymphatic fluid and is responsible for the metabolic environment of the scala media

Answer 14

Stria vascularis

Question 15

Definition of enlarged vestibular aqueduct at 1) midpoint, 2) operculum

Answer 15

Larger than 1) 1.5mm, 2) 2mm

Question 16

Enlarged vestibula aqueduct can lead to this in children, particularly after minor head trauma

Answer 16

Sudden, progressive SNHL

Question 17

Bundles of actin filaments that are stiff hairlike structures that deflect with mechanical diaturbances

Answer 17

Stereocilia

Question 18

Number of 1) inner hair cells in the modiolar side, 2) outer hair cells in the strial side

Answer 18

1) 3500, 2) 12000

Question 19

Side which stereocilia are longest

Answer 19

Strial side * Connected stereocilia move as a unit when the longest one is deflected

Question 20

Shape of 1)inner hair cells, 2) outer hair cells

Answer 20

1) flask, 2) cylindrical

Question 21

Contents of 1) inner vs 2) outer hair cells

Answer 21

1) organelles like golgi bodies and mitochondria (metabolic activity) , 2) microfilaments and microtubules (motile activity)

Question 22

Sites for presynaptic vesicle docking for subsequent stimulation

Answer 22

Synaptic bars

Question 23

1) Type 1 and 2) Type 2 nerve fibers in terms of a) polarity, b) size, c) myelination, d) percentage, e) site of innervation

Answer 23

Type 1: a) bipolar, b) large, c) myelinated, d) 95%, e) inner hair cells; Type 2: a) unipolar, b) small, c) un- or myelinated, d) 5%, e) outer hair cells

Question 24

All peripheral auditory information enters the CNS through this site, where initial auditory processing occurs

Answer 24

Cochlear nucleus * Located along the floor of the lateral recess of thr 4th ventricle

Question 25

Dorsal cochlear nucleus

Answer 25

Role in orienting to sound, potential site for generation of tinnitus

Question 26

Ventral cochlear nucleus

Answer 26

Initial processors of auditory nerve information

Question 27

1) Anterior ventral vs. 2) Posterior ventral cochlear nucleus

Answer 27

1) large caliber, sound localization; 2) fine, frequency/spectral shape, and sound intensity

Question 28

First auditory center to receive binaural innervation

Answer 28

Superior olivary complex

Question 29

Location of the superior olivary complex

Answer 29

Pons

Question 30

MedSuperiorOlive vs LatSuperiorOlive: interaural time delays vs intensity differences

Answer 30

MSO: interaural time delays; LSO: interaural intensity differences

Question 31

Superior Olivary Complex 1) Ascending pathway is for? 2) Descending pathway is for?

Answer 31

1) Sound localization; 2) Cochlear sensitivity or tuning

Question 32

Closely associated with the SOC, this also plays a role in sound localization and processing, also a component of the acoustic startle reflex pathway

Answer 32

Lateral lemniscus * Pathways through this correlate with wave III-V of ABR

Question 33

This part receives extensive innervation from higher and lower brain regions

Answer 33

Inferior colliculus

Question 34

Location of inferior colliculus

Answer 34

Midbrain

Question 35

Sound localization, frequency determination, integration of auditory and nonauditory systems

Answer 35

Principal functions of inferior colliculus * Sound localization is also a function of Dorsal Cochlear Nucleus, Anterior ventral cochlear nucleus, Ascending SOC

Question 36

Inferior colliculus is divided into 3 main neuronal groups, namely

Answer 36

1) central nucleus, 2) cortex, 3) paracentral nucleus

Question 37

Receives non auditory information from the somatosensory system

Answer 37

Paracentral nucleus of inferior colliculus

Question 38

Dominant region, has laminar organization, receives projections frim contralateral cochlear nucleus (direct, monaural), SOC (indirect, bilateral), lateral lemniscus (polysynaptic)

Answer 38

Central nucleus of inferior colliculus

Question 39

Innervation is primarily from the forebrain, including primary and secondary auditory cortices

Answer 39

Cortex of the inferior colliculus

Question 40

Other interactions of inferior colliculus: 1) associated with saccadic eye movement, 2) multiple auditory and nonauditory cortical structures

Answer 40

1) Superior colliculus, 2) Medial geniculate body

Question 41

Portal for all ascending auditory innervation to the telencephalon

Answer 41

Medial geniculate body of the thalamus

Question 42

Division of the medial geniculate body: 1) that has tonotopic organization, 2) plays a role in attending to acoustic stimuli, 3) largest, and plays a role in arousal to auditory stimuli

Answer 42

1) ventral division, 2) dorsal division, 3) medial division

Question 43

Which lobe of the brain is the human auditory cortex located

Answer 43

Temporal lobe

Question 44

Broadman area of 1) primary auditory cortex, 2) secondary auditory cortex

Answer 44

1) 41, 2) 42

Question 45

Area for receptive language and is dominant on the left side (Eponym and Broadmann area)

Answer 45

Wernicke, Broadmann area 22

Question 46

Cortical regions in the inferior parietal lobe that integrate auditory, somatosensory and visual information (2, name and broadmann area)

Answer 46

Angular Gyrus BA 39, Supramarginal Gyrus BA 40

Question 47

Site for expressive language and musical syntax, left hemisphere dominant (eponym and broadmann areas)

Answer 47

Broca, Broadmann area 44 and 45

Question 48

Also implicated in tinnitus production

Answer 48

Cerebellum * Dorsal cochlear nucleus also implicated in tinnitus production

Question 49

Auditory cortex also projects to (3)

Answer 49

Medial geniculate body (cortex), SOC (brainstem), inferior colliculus (midbrain)