Special Senses: Hearing Study Guide

Question 1

2 major functions of the human ear

Answer 1

• human hearing apparatus allows us to hear a large range of sound
• Equilibrium (balance) receptors inform the nervous system of head movements and positions

Question 2

3 major areas of the ear

Answer 2

• External (Outer) Ear: hearing only
• Middle Ear (Tympanic Cavity): hearing only
• Internal (Inner) Ear: hearing + equilibrium

Question 3

which area of the ear maintains equllibrium

Answer 3

internal (inner) ear

Question 4

3 main parts of external ear

Answer 4

• auricle (pinna)
• external acoustic meatus (auditory canal)
• tympanic membrane (eardrum)

Question 5

Auricle (Pinna)

Answer 5

shell-shaped outer structure; functions to funnel sound waves into the auditory canal
- Helix: cartilaginous rim
- Lobule: fleshy earlobe

Question 6

External Acoustic Meatus (Auditory Canal)

Answer 6

• Short, curved tube lined with skin bearing hairs, sebaceous glands, and ceruminous (earwax) glands
• Transmit sound waves to the eardrum

Question 7

Tympanic Membrane (Eardrum)

Answer 7

• Boundary between the external and middle ears
• Thin, translucent connective tissue membrane
• Vibrates in response to sound
• Transfers sound energy to the bones of the middle ear

Question 8

structures on the medial and lateral sides of the tympanic cavity

Answer 8

Lateral: eardrum
Medial: bony wall containing the oval and round membranous windows

Question 9

pharyngotympanic tube

Answer 9

• connects the middle ear to the nasopharynx
• usually a flattened tube – it can be opened by yawning or swallowing

Question 10

pharyngotympanic tube function

Answer 10

An opened pharyngotympanic tube equalizes pressure in the middle ear cavity with external air pressure

Question 11

otis media

Answer 11

Middle ear inflammation; often occurs with a sore throat – especially in children with shorter, more horizontally running pharyngotympanic tubes

Question 12

auditory ossicles

Answer 12

3 small bones named for their shape in the middle ear

Question 13

auditory ossicles in order from medial to lateral

Answer 13

Stapes, incus, malleus

Question 14

tensor tympani and stapedius

Answer 14

Skeletal muscles that contract reflexively in response to loud sounds and prevent damage to the hearing receptors

Question 15

2 major divisions of the internal ear

Answer 15

• Bony labyrinth
• Membranous labyrinth

Question 16

fluid found in each division of the internal ear

Answer 16

• Bony labyrinth: filled with perilymph
• Membranous labyrinth: filled with potassium rich endolymph

Question 17

What is the function of perilymph and endolymph

Answer 17

Conduct the sound vibrations involved in hearing an respond to the mechanical forces occurring during changes in body position

Question 18

3 regions of the bony labyrinth

Answer 18

Vestibule, semicircular canals, cochlea

Question 19

What’s the vestibule?

Answer 19

• Central, egg shaped cavity of bony labyrinth; contains 2 membranous connected sacs

Question 20

2 compartments of vestibule

Answer 20

• Saccule: continuous with the cochlear duct
• Utricle: continuous with the semicircular canals

Question 21

function of vestibule compartments

Answer 21

Membranous sacs house equilibrium receptor regions (maculae) – respond to the pull of gravity and changes in the position of the head

Question 22

Semicircular Canals

Answer 22

3 canals oriented in 3 planes of space – anterior, lateral, and posterior - regulate balance and sense head position

Question 23

lines each semicircular canal

Answer 23

Membranous semicircular ducts - they communicate with the utricle

Question 24

cochlea

Answer 24

Small spiral, conical, bony chamber – size of a split pea - extends from the anterior vestibule

Question 25

modiolus

Answer 25

bony pillar that the cochlea spirals around about 2.5 times

Question 26

Ampulla

Answer 26

enlarged area of each semicircular duct; contains receptors for rotational movements of the head

Question 27

Spiral organ

Answer 27

rests atop the basilar membrane and is composed of supporting cells and hearing receptor cells

Question 28

3 chambers within the cochlea

Answer 28

• Scala vestibule: abuts the oval window, contains perilymph
• Scala media (cochlear duct): contains endolymph
• Scala tympani: terminates at round window, contains perilymph

Question 29

where are hearing receptor cells located?

Answer 29

spiral organ

Question 30

how are hearing receptor cells connected to the cochlear nerve?

Answer 30

Afferent fibers of the cochlear nerve coil about the bases of the hair cells and run from the spiral orga through the modiolus of the brain

Question 31

Conduction Deafness

Answer 31

occurs when something hampers sound conduction to the fluids of the internal ear (Ex: impacted earwax, otis media)

Question 32

Sensorineural Deafness

Answer 32

results from damage to the neural structures – anywhere from the cochlear hair cells to the auditory cortical cells
* progressive loss of hair cells, a single explosive sound, prolonged exposure to loud sounds, strokes, degeneration of the cochlear nerve, tumors, or congenital defects