Anatomy L4 Ear Anatomy and Equilibrium/Balance

what are the regions of the ear?

external/outer ear

middle ear

internal ear

what structures compose the outer ear?

auricles (aka pina or helix)

external auditory meatus

tympanic membrane (TM)

what is the function of the auricles?

collect sounds

what part of the auricles is devoid of cartilage?

lobule aka the ear lobes

what is the function of the external auditory meatus?

conducts sounds to the tympanic membrane

describe the external auditory meatus

a curved tube of cartilage (lateral 1/3) & bone (medial 2/3) leading into temporal bone

what are ceruminous glands?

glands that secrete cerumen aka ear wax

how does hearing sounds work in the external ear?

the auricle will collect sound and direct it to the external auditory meatus where the sound will continue to flow down to the tympanic membrane

what is the shape of the TM?

cone shaped

the middle ear contains

the tympanic cavity

• auditory ossicles

what are auditory ossicles?

tiny mobile bones

• malleus, incus, stapes

what are some important structures of the TM?

what is the function of the TM?

separates the external ear from the middle ear

transmits sound from air to the ossicles

what is a perforation?

a hole

what is the eustachian tube? what does it do?

aka:

• auditory tube

• pharyngotympanic tube

Connects the middle ear to the nasopharynx

Equalizes pressure in the middle ear

Allows air to move the TM during valsalva

the internal ear contains

3 semicircular canals

vestibule

cochlea

cochlea duct

what is the function of the 3 semicircular canals?

aid in equilibrium

what planes are the 3 semicircular canals? function

anterior: detects nodd up and down

posterior: detects tilting left and right

lateral: detects shaking side to side

the the 3 semicircular canals are involved in what type of equilibrium?

dynamic equilibrium

what are the organs found in the the 3 semicircular canals?

the ampulla which contains the:

crista ampullaris

• contain hair cells covered in cupula (gelatinous)

what is the cochlea divided into?

Oval window (entrance)

Round window (exit)

what is the vestibule divided into? what do they detect?

Utricle

• detects side to side and back and froth movement

Saccule

• detects up and down movemnets

what are otoliths?

hard, calcium carbonate structures

where are otoliths located?

saccule and utricle

aka the vestibule

what are otoliths sensitive to?

to gravity and static/linear acceleration

what stimulates hair cells when the head moves?

otoliths

what is the cochlea duct divided into?

scala vestibuli

scala media

scala tympani

where are the stereocilia located?

the corti in the cochlea duct

what serves as a receptor for sound?

stereocilia

• the cochlear hair cells

what does the stereocilia do?

converts vibration into nerve impulses

the sense of equilibrium consists of what?

static (head straight) equilibrium and dynamic equilibrium

what is static equillibrium?

the position of the head is sensed while head and body are still

what is dynamic equillibrium?

when the head and body move or rotate, the motion is detected, aiding in balance

what is the ampullae responsible for?

balance

what is the cupula responsible for?

balance