Ear (7) Flashcards
ear structure general
aka vestibulocohlear apparatus
- external ear: collect sound waves, ends @ tympanic membrane
- middle ear: tympanic cavity, amplify vibrations, transmit to fluid in internal
- internal: convert to nerve impulses to detect sound + orientation + acceleration of head
external ear
function
sound localization and amplification
vibrations of tympanic membrane convert sound waves > mechanical vibrations
external ear
parts
- auricle = covered w/ thin skin, has hair follicles + sweat/sebaceous glands
- external acoustic meatus = ceruminous glands aka modified sweat glands give waxy cerumen
- tympanic membrane = lined externally by strat squamous from ectoderm + internally by simple cuboidal from endoderm
middle ear ossicles
- malleus = hammer, attaches to tympanic membrane
- incus = anvil
- stapes = stirrup, sits in oval window that opens into vestibule of inner ear
middle ear attenuation reflex
muscles tensor tympani + stapedius = dampen vibration of ossicles
middle ear histology
lined w/ pseudostratified columnar epi
mucous glands in/around auditory tube
internal ear function
1.convert fluid waves into nerve impulses
2.hearing and balance
3.vestibulocochlear nerve CN VIII
labyrinths of internal ear
- bony- space w/i temporal bone filled w/ perilymph, has cochlea>vestibule>semicircular canals
- membranous-sacs suspended w/i bony, filled w/ endolymph
-divided into vestibular and cochlear labyrinth
bony labyrinth
-semicircular canals are 90 degrees to each other
-vestibule has oval and round windows
-cochlea coils around modiolus (central bone core)
membranous labyrinth
-cochlear= duct with sensory organ (spiral organ of corti)
-vestibular = saccule and utricle w/ macula sensory organs + semicircular ducts w/ crista ampullaris sensory organ
vestibular sensory organs
hair cell organization
hair cells embedded in a gel
apical surface w/ one kinocilium + stereocilia
-asymmetrical so detects direction if towards/away from kinocilium
two types (I and II) of cells
macula
@utricle and saccule of vestibule
saccule= detect vertical acceleration
utricle= horizontal acceleration
hair cells embedded in otolithic membrane surrounded by supporting cells
otolithic membrane
macula
gelatinous sheet w/ small cristals aka otoconia or otoliths lining surface
crista ampullaris
detect angular/rotational acceleration @ampullae of semicircular ducts
hair cells embedded in cupula that deflects in opposite direction of movement
cupula is gelatinous cap over sensory epithelium
crista ampullaris
detect angular/rotational acceleration @ampullae of semicircular ducts
hair cells embedded in cupula that deflects in opposite direction of movement
cupula is gelatinous cap over sensory epithelium
vertigo
otoconia become dislodged from otolithic membrane so fall into ampulla = stimulate crista ampullaris
erroneus sense of spinning
chambers of cochlear labyrinth
- scala vestibuli
- scala tympani
- scala media
scala vestibuli
has perilymph
communicates w/ tympanic cavity thru oval window
vestibular membrane at base to divide from scala media
scala tympani
has perilymph
communicates w/ tympanic cavity thru round window
basilar membrane above
basilar membrane
attaches to osseous spiral lamina
supports spiral organ of corti
scala media
aka cochlear duct
-houses spiral organ of corti for hearing
tectorial membrane overlies, hair cells embedded w/i, anchored by spiral limbus
-lateral wall = stria vascularis (syn endolymph)
-spiral ligament attaches duct to outer wall cochlea + supports basilar membrane
spiral organ of corti
2 main cell types:
1. sensory aka hair cells, inner and outer with stereocilia embedded w/i tectorial membrane
2. supporting cells aka phalangeal (inner/outer, support hair cells) and pillar (inner/outer, form tunnel of corti)
cochlear hair cells
symmetrical and no kinocilium
support/anchored by phalangeal cells
-inner phalangeal fully surround inner hair cells (1 row wide)
-outer phalangeal partially surround outer hair (3-4 rows)
