Chapter 15.7 Ear Anatomy

Question 1

Shell shaped structure surrounding external acoustic meatus
Composed of elastic cartilage covered with thin skin
Function: funnels sound waves into auditory canal

Answer 1

Auricle

Question 2

Cartilaginous rim in auricle

Answer 2

Helix

Question 3

Fleshy earlobe of auricle

Answer 3

Lobule

Question 4

Short, curved tube; Lined with skin bearing hairs, sebaceous glands, and ceruminous (earwax) glands
Transmits sound waves to eardrum

Answer 4

External acoustic meatus (auditory canal)

Question 5

Boundary between external and middle ears; Thin, translucent connective tissue membrane
A.k.a eardrum
Vibrates in response to sound
Transfers sound energy to bones of middle ear

Answer 5

Tympanic membrane

Question 6

Small, air-filled mucosa-lined cavity in temporal bone
Flanked laterally by eardrum and medially by bony wall
Bony wall contains: oval, round membranous windows

Answer 6

Middle ear

Question 7

If _____ is not equal on both sides of tympanic membrane, sounds are distorted

Answer 7

Pressure

Question 8

Connects middle ear to nasopharynx, equalizes pressure in middle ear with external air pressure
Formerly called eustachian tube
Usually flattened tube, but can be opened by yawning or swallowing to equalize pressure

Answer 8

Pharyngotympanic tube

Question 9

Three small bones in tympanic cavity, named for shape
Bones: Malleus, Incus, Stapes
Transmit vibratory motion of eardrum to oval window

Answer 9

Auditory ossicles

Question 10

The ‘hammer’ is secured to eardrum

Answer 10

Malleus

Question 11

The ‘anvil’ portion, in the middle

Answer 11

Incus

Question 12

The “stirrup” base fits into oval window
Most interior bone

Answer 12

Stapes

Question 13

Muscle that contracts reflexively in response to loud sounds to limit ossicle vibration and limit damage to hearing receptors

Answer 13

Tensor tympani

Question 14

Middle ear inflammation
Commonly seen in children with sore throat
Most frequent cause of hearing loss in children
Acute infectious forms cause eardrum to bulge outward and become inflamed

Answer 14

Otitis media

Question 15

A.k.a labyrinth
Located in temporal bone behind eye socket
2 divisions: bony labyrinth, membranous labyrinth

Answer 15

Inner ear

Question 16

System of bony channels and cavities in the temporal bone
3 regions: vestibule, semicircular canals, cochlea
Filled with perilymph fluid (similar to CSF)

Answer 16

Bony labyrinth

Question 17

Inside of bony labyrinth, containing series of membranous sacs and ducts
Filled with potassium rish endolymph

Answer 17

Membranous labyrinth

Question 18

Central eg-shaped cavity of bony labyrinth
Contains two membranous sacs: saccule and utricle
Sacs house equilibrium receptor regions called maculae

Answer 18

Vestibule

Question 19

Continuous with semicircular ducts; superior part of vestibule

Answer 19

Utricle

Question 20

Continuous with cochlear duct; part of vestibule

Answer 20

Saccule

Question 21

Respond to gravity and changes in position of head; Flat epithelium patch containing hair cells and support cells
Part of utricle

Answer 21

Maculae

Question 22

Part of hair cells called stereocilia, very special one

Answer 22

Kinocilium

Question 23

Jelly-like mass studded with otoliths; stereocilia embedded here

Answer 23

Otolith membrane

Question 24

Increase membrane’s weight and increase its inertia

Answer 24

Otolitlhs

Question 25

Three canals oriented in three planes of space: anterior, lateral, and posterior

Answer 25

Semicircular canals

Question 26

Line each semicircular canal and communicate with utricle

Answer 26

Membranous circular canal

Question 27

Enlarged area of ducts of each canal that houses equilibrium receptor region

Answer 27

Ampulla

Question 28

Contains receptors that respond to angular (roational) movements of the head Each crista has supporting cells and hair cells that extend into a gel like mass = ampullary cupula

Answer 28

Crista ampullaris

Question 29

Small, spiral, conical bony chamber that extends from vestibule Can be divided into 3 chambers, including cochlear duct

Answer 29

Cochlea

Question 30

What are the three chambers of the chochlea?

Answer 30

1. Scala vestibuli 2. Scala media 3. Scala tympani

Question 31

Touches oval window, contains perilymph

Answer 31

Scala vestibuli

Question 32

A.k.a. cochlear duct Contains endolymph Houses spiral organ which contains receptors for hearing

Answer 32

Scala media

Question 33

Terminates at round window; contains perilymph

Answer 33

Scala tympani

Question 34

Where scala tympani and scala vestibuli are continuous with each other

Answer 34

Helicotrema

Question 35

"Roof" of cochlear duct that separates scala media from scala vestibuli

Answer 35

Vestibular membrane

Question 36

What "Floor" of cochlear duct is composed

Answer 36

Basilar membrane

Question 37

External wall of scala media

Answer 37

Stria vascularis

Question 38

Bony pillar that cochlea coils around

Answer 38

Modiolus

Question 39

Gel-like substance where stereocilia of spiral organ are enmeshed

Answer 39

Tectorial membrane

Question 40

The ________ branch of cranial nerve III runs from spiral organ to brain

Answer 40

Cochlear

Question 41

The _________ branch of cranial nerve III runs from hair cells in the utricle, saccule, and

Answer 41

Vestibular