Auditory and Vestibular

Question 1

Structural anatomy of the outer ear

Answer 1

Pinna: collects auditory information; variable depending on predator/prey

Auditory canal (external auditory meatus)

Question 2

Innervations of Ear Ossicles

Answer 2

Malleus: tympani m. innervated by trigeminal nerve

Stapes: stapedius m. innervated by a twig of the facial nerve

Question 3

Pathways of Infection

Answer 3

Eustachian Tube, Otidis Media, conductive hear loss, sensorineural hearing loss

Question 4

Types of Hearing Loss

Answer 4

Outer ear damage: rupturing the ear drum/otitis externa
Conduction hearing loss: middle ear infections- fluid/pus
Meniere’s disease: Fluctuating, progressive, unilateral
(in one ear) or bilateral (in both ears) hearing loss, usually in lower frequencies, caused by Endolymphatic hydrops: excessive fluid within the labrynth

Question 5

Mechanics of sound transduction

Answer 5

vibration of organ of corti, displacement of hair cells by tectorial membrane
Stereocilia defection toward kinocilium depolarizing, deflection away from kinocilium hperpolarizing, hair cells evoke activity in peripheral process of spiral ganglion cells

Question 6

Vestibular Organs

Answer 6

otolithic (utricle ,salule) – linear accelleration, otolithic membrane, hair cells, otolith – LVST –righting reflex
Semicircular canals – angular accelleratin – ampula – crista ampularis – cupula – VOR – eye movements

Question 7

VOR

Answer 7

vestibulo-ocular reflex

acts to move the eye in equal magnitude when turning the head

Question 8

Structural anatomy of the middle ear

Answer 8

Sound information that is vibratory in the air
Malleus, Incus, Stapes (lateral to medial)
Protection mechanisms for loud, sudden sounds
Malleus: tympani m. innervated by trigeminal nerve
Manubrium- long process of the malleus seen on the otoscopic examination
Change in pressure (high-low; airplane)
Stapes: stapedius m. innervated by a twig of the facial nerve
these muscles contract in response to loud sounds, phonation (voicing)
and mastication; and are a protective mechanism against acoustic trauma
(nothing inside cochlea regenerates)
Reduce the amount of energy that is being passed into the inner ear

Question 9

Structural anatomy of the inner ear

Answer 9

Cochlea, apex, base, scala vestibuli, scala tympani, scala media, osseous spiral lamina, spiral ganglion
Reisner’s membrane, basilar membrane, stria vascularis, organ of corti, inner hair cells, outer hair cells, stereocilia,
kinocilim, tectorial membrane