Ears Flashcards
Cerumen
ceruminous glands, that protect the ear from infections and provides a barrier to insects and water
Perilymph
fluid within the bony labyrinth, surrounding membranous labyrinth
Endolymph
fluid within membranous labyrinth
Modiolus
- part of the cochlea and its conical-shaped structure that consists of spongy (porous) bone located at the center of the cochlea
- contains spiral ganglion
Maculae
static equilibrium receptors located perpendicular to each other in the utricle & saccule
Saccule
a sac of membranous labyrinth
Utricle
connected to the saccule by small duct
Otolith
calcium carbonate crystals forming a layer of otolithic membrane
Ampulla
enlarged swelling at the end of each semicircular canal
what structures are in the inner ear?
- bony labyrinth-cochlea
- cochlear duct
- bony labyrinth
- perilymph
- membranous labyrinth
- endolymph
- cochlea
- scala vestibuli
- scala tympani
- spiral organ
what structures are in the outer ear?
- auricular cartilage
- external auditory meatus
- cerumen/ ear wax
- pinna/ auricle
what structures are in the middle ear?
- tympanic cavity
- tympanic membrane/ eardrum
- auditory ossicles/ ear bones
- malleus (“hammer”)
- incus (“anvil”)
- stapes (“stirrups”)
- oval (vestibular) window
- round (cochlear) window
- auditory tube (eustachian tube)
What cranial nerve is responsible for equilibrium and hearing?
vestibulocochlear nerve (CN VIII)
What cranial nerve is responsible for sight?
optic nerve (CN V)
what are the 3 auditory ossicles?
- malleus
- incus
- stapes
difference between round window & oval window?
round window:
covered by a secondary tympanic membrane, which bulges outward from the fluid movement
oval window:
it is filled base of the stapes, which pushes inward
anatomic structures in hearing?
- sounds waves reaching the ear directed by the pinna goes to the external auditory meatus -> tympanic membrane
- tympanic membrane vibrated by the sound waves
- malleus, passes on and amplifies the vibrations (incus & stapes) to the windows
- Vibrations of the oval window (stapes) sets the perilymph into a wave motion
- that travels through the scala vestibuli & scala tympani to the round window
- The round window bulges into the middle ear and then back into the scala tympani, reversing the fluid wave movement
- Vibrations of the scala vestibuli & scala tympani generate wave motion of the endolymph within the cochlear duct displacing the hair cells of the spiral organ
- the movement of hair cells on spinal organ = nerve impulses
- the nerve impulse passes through the cochlear branch of the vestibulocochlear nerve (CN VIII) to the hearing centers in the brain
anatomic structures in static equilibrium?
- concerned with “body (head) position” relative to gravity
- otolithic membrane is moved by the weight of the otoliths under the pull of gravity
anatomic structures in dynamic equilibrium?
- when the head moves, pushes the cupula bending the hair cells
- sends impulses to the vestibular branch (via CN VIII)
- detecting angular rotational acceleration of declaration of head
scala vestibuli
canal of bony labyrinth communicating with the vestibule
hair (receptor) cells
receptor cells of the maculae carrying impulses to the vestibular branch of CN VIII
otolithic membrane: holds hair cells at which they are embedded in
crista
receptor organ found in the ampulla of each semicircular duct
composed of hair receptor cells and supporting cells = senses motion of head
vestibule
the central, expanded portion of the inner ear
membranous labyrinth of the vestibule
consists of two sacs: saccule & utricle
articular cartilage
- the elastic framework of the pinna & external auditory meatus
- covered on both sides of the skin
external auditory meatus
the passageway from the pinna to ear drum
- vertical & horizontal canal
middle ear/ tympanic cavity
contains auditory ossicles & opening of auditory tube
tympanic membrane/ear drum
- thin, semitransparent partition between the external auditory meatus & the middle ear
- ear drum is vibrated by sound waves
auditory ossicles/ear bones
- 3 bones extend across the middle ear from the ear drum to the oval window of the cochlea
- setting up vibrations in the fluid of the cochlea
auditory tube (eustachian tube)
- the passageway between the middle ear & nasopharynx
- functions:
- equalize pressure on both sides of the eardrum
- protecting from rupture
- swallowing & yawning open auditory tubes = air into the middle ear
bony labyrinth
series of cavities in the temporal bone
- lined with the periosteum
- divided into the vestibule, cochlea, and semicircular canals
perilymph
fluid within the bony labyrinth, surrounding the membranous labyrinth
membranous labyrinth
- a series of tubes and sacs within the bony labyrinth
- Separates the two canals of bony labyrinth and forms the cochlear duct
cochlea
- snail shell-like part of the inner ear associated with hearing
- Consists of an outer bony coil and an inner membranous cochlear duct
endolymph
the fluid within the membranous labyrinth
spiral organ
cochlear duct (scala media)
- the spiral canal extending from the base to the apex of the cochlea, between the canals of the bony labyrinth
- filled with endolymph and contains the spiral organ
- divides the bony spiral labyrinth into two channels: the scala vestibuli and the scala tympani
bony labyrinth-cochlea
a bony, spiral canal making a number of turns around a central bony core
