The Ear Flashcards
functions of the ear
enables us to hear and maintain balance
three parts of the ear
outer, middle, inner ear
mechanoreceptors
the receptors (that are concentrated in the ear) that detect sound stimuli and head movements
position of ear
- the two pinnae are outside the skull on opposite sides of the head
- rest is embedded in temporal bone of skull
outer ear consists of…
- pinna
- external auditory canal
pinna
cartilage covered with skin
- collects and directs sound waves
external auditory canal
curved tube which leads to tymphatic membrane
- transmits sound waves from pinna to tymphatic membrane
middle ear consists of…
- tymphatic membrane
- ossicles
- oval and round window
- eustachian tube
middle ear definition
small air-filled cavity in temporal bone with a mucous membrane
what is the tymphatic membrane
EARDRUM
covers the opening between the middle ear and the external auditory canal
eardrum function
converts sound waves to vibrations that are transmitted to malleus
the three ossicles
malleus/hammer
incus/anvil
stapes/stirrup
ossicles function
ligaments join the three ossicles and form a lever system to connect inner and outer ear
oval window
an opening covered by thin membrane that connects middle and inner ear
- transmits vibrations between the two
round window
basically the same as the oval window, except its below the oval window
eustachian tube function
connects middle ear to pharynx and ensures pressure is the same on both sides of the eardrum
inner ear consists of
- bony labyrinth
- membranous labyrinth
labyrinths consist of
vestibular apparatus for balance
cochlea for hearing
bony labyrinth
canals and cavities within the temporal bone
membranous labyrinth
membranous tubes and sacs filled with endolymph (fluid) and floats in the perilymph
vestibular apparatus consists of
- utriculus and sacculus
- semicircular canals
utriculus and sacculus
- filled with endolymph, float in perilymph
- has a layer of hair cells in a jelly-like layer
- structure forms a macula
functions of utriculus and sacculus
detect the position of the head in space
semicircular canals
three canals with an ampulla containing cristae at the base
how balance is coordinated in the cerebellum
nerve fibres from the vestibular nerve conduct impulses to the cerebellum
crista
a receptor that detects changes in speed or movement of head
semicircular canals function
detects changes in speed or movement of head
macula
a receptor that detects the position of the head in space
ampulla
a part at the base of the semicircular canal containing a crista
cupula
a jelly-like cap that forms part of the crista
cochlea
long, coiled tube that is divided into three canals
the three scala
scala vestibuli
scala media
scala tympani
scala vestibuli
- upper canal
- filled w perilymph
- bordered by oval window
scala media
- middle canal
- contains hearing receptors
- filled with endolymph
scala tympani
- lower canal
- filled w perilymph
- ends in round window
helicotrema
the opening at the tip of the cochlear tube that joins the two outer canals of the cochlea
vestibular membrane
seperates the media and vestibular
basilar membrane
seperates media and tympani
organ of corti
a structure formed by hair cells and tectorial membrane. it contains hearing receptors
function of organ of corti
detect vibrations and convert them into nerve impulses
functions of auditory nerve
conducts impulses to cerebral cortex to produce a hearing sensation, and to cerebellum to coordinate balance
two types of deafness
conductive
neural
conductive deafness
- when one of the mechanisms that transmit sound waves to the external ear do not work properly
- often temporary, surgery
neural deafness
- involves a problem w the inner ear, and is usually permanent
- can be fixed w hearing aid, cochlear implant
causes of deafness
- age
- heredity
- head/middle/inner ear injury
symptoms of middle ear infection
- earache
- fever
- hearing loss
treatment of middle ear infection
- antibiotics
- eardrops
- surgery
