Lecture 17: The ear

Question 1

Auricle

Answer 1

Pinna of the ear and auditory canal
Integument overlying elastic cartilage
Integument is thin, keratinized stratified squamous epithelium

Question 2

External auditory meatus

Answer 2

Outer third of ear is elastic cartilage
Inner two thirds is bone
Lining of ear canal is stratified squamous with sebaceous and ceruminous glands

Question 3

Tympanic membrane

Answer 3

Separates EAC from middle ear
Core is formed from vascularized, innervated tissue
External surface is thin skin
Internal surface is simple cuboidal epithelium

Question 4

Malleus

Answer 4

Attaches to TM

Question 5

Incus (anvil)

Answer 5

Intermediate bone b/w malleus and stapes

Question 6

Stapes

Answer 6

Third bone in series, inserts into oval window

Question 7

Oval window

Answer 7

Stapes attaches to membrane

Oval window opens into scala vestibuli

Question 8

Round window

Answer 8

Membrane covered region at the end of scala tympani

Question 9

Muscles of inner ear

Answer 9

Tensor tympani- inserts on malleus
Stapedius- inserts on stapes
These muscles contract reflexively in response to loud sounds in order to dampen the vibrations of the auditory ossicles

Question 10

Regions of the inner ear

Answer 10

Bony labyrinth
Membranous labryinth
Vestibular organ
Auditory organ

Question 11

Bony labyrinth

Answer 11

Complex system of canals and chambers embedded in temporal bone
Filled with high-sodium content perilymph

Question 12

Bony labyrinth consists of

Answer 12

Semicircular canals
Cochlea
Scala vestibuli
Scala tympani

Question 13

Membranous labryinth

Answer 13

Complex system of membranous structures embedded within chambers of the bony labyrinth
Filled with high-potassium content endolymph

Question 14

Vestibular organs

Answer 14

Patches of sensory structures that respond to change in position
Consists of
-Maculae of saccule and utricle
-Cristae ampullaris of the semicircular canals

Question 15

Epithelium of maculae of saccule and utricle

Answer 15

Columnar supporting cells
Vestibular hair cells-in contact w/afferent nerve endings
Otolithic membrane

Question 16

Otolithic membrane

Answer 16

Gelatinous layer containing calcium carbonate crystals called otoliths that overlies the epithelium
Stereocilia are embedded in this layer
Movements of the head displaces the otolithic membrane and causes a sensory impulse

Question 17

Epithelium of cristae ampullares of semicircular ducts

Answer 17

Columnar supporting cells
Hair cells
Capula

Question 18

Capula

Answer 18

Gelatinous layer similar to otolithic membrane but without otoliths
Movement of the head creates shear forces b/w semicircular canals and the contained fluid
Movement of fluid displaces the capula and causes stereocilia to bend

Question 19

Auditory organ consists of

Answer 19

Cochlear duct (scala media)
Organ of corti

Question 20

Cochlear duct contains

Answer 20

Scala vestibuli
Scala tympani
Vestibular and basilar membranes
Stria vascularis

Question 21

Cochlear duct divides bony cochlea into

Answer 21

Scala vestibuli and scala tympani

Question 22

Roof of cochlear duct

Answer 22

Vestibular membrane

Question 23

Floor of cochlear duct

Answer 23

Basilar membrane

Question 24

Lateral aspect of cochlear duct

Answer 24

Stria vascularis- participates in formation of endolymph

Question 25

Organ of corti lies

Answer 25

On the basilar membrane