Auditory System

Parts of the outer ear

The visible part of the ear consisting of three parts: the pinna, the ear canal, and the eardrum.

parts of the middle ear

Ossicles: Three tiny bones that amplify sound waves and transmit them to the inner ear. Eustachian tube: A narrow tube that connects the middle ear to the back of the throat, helping to equalize pressure. Tympanic membrane: A thin membrane that vibrates in response to sound waves, separating the middle ear from the outer ear.

parts of the inner ear

The inner ear has three parts: cochlea for hearing, vestibule and semicircular canals for balance.

3 parts of the ear that dampen sounds

Malleus, Incus, stapes

What muscles can wiggle the ears, what CN is it innervated by?

auricularis muscles, anterior, posterior, and superior; vestigial muscles

innervated by CN 7

What are the first order vestibular afferent cell bodies found?

Scarpa’s ganglion

what fissure does V1 pass through

superior orbital fissure

what does V2 pass through

foramen rotundum

what does v3 pass through

foramen ovale

what 2 cranial nerves create the tympanic or acoustic reflex

CN 5 and 7

pitch of sound

determined by the frequency fo pressure wave

frequency

depends on which part of the organ of corti is active

intensity

depends on how many nerve cells respond

location

depences on the interpretation by cortex

where is bilateral sound processed?

cortex

Tonotopic

organization from base of cochlea to apex

where do high frequency waves register?

base of the cochlea

perilymph

like CSF and is continuous with it, high Na+ and low K+

endolymph

like intracellular content, low Na+ and high K+

what is endolymph produced by? where does it drain?

cochlear duct in stria vascularis, drained thorugh endolymphatic sac

Where are the tight juntioncs of the endolymph found?

tight junctions of cell in the wall of the cochelar duct

How is stereocillia and Koniocillum differ?

kinocillum touched to outer hair shell