Chapter 15: Balance and Hearing

Question 1

what are the three divisions of the ear?

Answer 1

external, middle, and internal ear

Question 2

external and middle ear

Answer 2

for hearing

Question 3

inner ear

Answer 3

for balance

Question 4

what are the structures of the external ear

Answer 4

auricle or pinna: elastic cartilage covered by skin

external auditory canal, which is lined with hairs and ceruminous glands that produce ear wax.

tympanic membrane (“ear drum”): the barrier between the external and internal ear. Sound waves cause it to vibrate.

Question 5

what are the structures of the middle ear?

Answer 5

separated from inner ear through two windows, oval and round

there are two passages for air: auditory or eustachiantube, and the mastoid air cells.

Ossicles: malleus, incus, and stapes: transmit vibrations from eardrum to oval window. the three smallest bones in the body.

Question 6

what are the structures of the inner ear?

Answer 6

bony labryinth: tunnels and chambers in the temporal bone (cochlea- hearing, vestibule- balance, and semisircular canals - balance)

membranous labyrinth: membranous tunnels and chambers suspended in the bony labyrinth.

endolymph: the fluid inside the inner ear

Question 7

spiral organ

Answer 7

the structure in the inner ear where the cochlear duct is located. Contains hair cells with hair-like projections at the apical ends. Microvilli called stereocilia.

Question 8

functions of the auditory portion of the ear

Answer 8

to translate sound waves (volume) and and frequencies (pitch).

Question 9

What are the two types of balance?

Answer 9

static and dynamic

Question 10

static balance

Answer 10

utricle and saccule of the vestibule (detects position of head in comparison to gravity and detects linear acceleration and deceleration)

Question 11

dynamic labryinth

Answer 11

semicircular canals evaluates the movement of the head in the three dimensional space.

Question 12

Describe the neural pathway for hearing

Answer 12

1. cochlear ganglion neurons synapse in the cochlear nucleus in the superior medulla oblongata
2. then the neurons pass through the superior olivary nucleus, which project to the trigeminal nerve nucleus
3. neurons from the superior olivary nucleus project into the inferior colliculi then to the thalamus
4. thalamus neurons terminate in the auditory cortex, which is located in the dorsal portion of the temporal lobe.