Ear (7)

Question 1

ear structure general

aka vestibulocohlear apparatus

Answer 1

1. external ear: collect sound waves, ends @ tympanic membrane
2. middle ear: tympanic cavity, amplify vibrations, transmit to fluid in internal
3. internal: convert to nerve impulses to detect sound + orientation + acceleration of head

Question 2

external ear

function

Answer 2

sound localization and amplification

vibrations of tympanic membrane convert sound waves > mechanical vibrations

Question 3

external ear

parts

Answer 3

1. auricle = covered w/ thin skin, has hair follicles + sweat/sebaceous glands
2. external acoustic meatus = ceruminous glands aka modified sweat glands give waxy cerumen
3. tympanic membrane = lined externally by strat squamous from ectoderm + internally by simple cuboidal from endoderm

Question 4

middle ear ossicles

Answer 4

1. malleus = hammer, attaches to tympanic membrane
2. incus = anvil
3. stapes = stirrup, sits in oval window that opens into vestibule of inner ear

Question 5

middle ear attenuation reflex

Answer 5

muscles tensor tympani + stapedius = dampen vibration of ossicles

Question 6

middle ear histology

Answer 6

lined w/ pseudostratified columnar epi

mucous glands in/around auditory tube

Question 7

internal ear function

Answer 7

1.convert fluid waves into nerve impulses
2.hearing and balance
3.vestibulocochlear nerve CN VIII

Question 8

labyrinths of internal ear

Answer 8

1. bony- space w/i temporal bone filled w/ perilymph, has cochlea>vestibule>semicircular canals
2. membranous-sacs suspended w/i bony, filled w/ endolymph
   -divided into vestibular and cochlear labyrinth

Question 9

bony labyrinth

Answer 9

-semicircular canals are 90 degrees to each other
-vestibule has oval and round windows
-cochlea coils around modiolus (central bone core)

Question 10

membranous labyrinth

Answer 10

-cochlear= duct with sensory organ (spiral organ of corti)
-vestibular = saccule and utricle w/ macula sensory organs + semicircular ducts w/ crista ampullaris sensory organ

Question 11

vestibular sensory organs

hair cell organization

Answer 11

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

Question 12

macula

Answer 12

@utricle and saccule of vestibule
saccule= detect vertical acceleration
utricle= horizontal acceleration

hair cells embedded in otolithic membrane surrounded by supporting cells

Question 13

otolithic membrane

macula

Answer 13

gelatinous sheet w/ small cristals aka otoconia or otoliths lining surface

Question 14

crista ampullaris

Answer 14

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

Question 14

crista ampullaris

Answer 14

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

Question 15

vertigo

Answer 15

otoconia become dislodged from otolithic membrane so fall into ampulla = stimulate crista ampullaris

erroneus sense of spinning

Question 16

chambers of cochlear labyrinth

Answer 16

1. scala vestibuli
2. scala tympani
3. scala media

Question 17

scala vestibuli

Answer 17

has perilymph

communicates w/ tympanic cavity thru oval window

vestibular membrane at base to divide from scala media

Question 18

scala tympani

Answer 18

has perilymph

communicates w/ tympanic cavity thru round window

basilar membrane above

Question 19

basilar membrane

Answer 19

attaches to osseous spiral lamina

supports spiral organ of corti

Question 20

scala media

Answer 20

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

Question 21

spiral organ of corti

Answer 21

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)

Question 22

cochlear hair cells

Answer 22

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)