Special Senses - EAR

Question 0

which part of the ear conducts sound to the oval window

Answer 0

the middle ear

Question 1

what part of the ear is responsible for collecting sound waves and focusing them inward

Answer 1

the external ear

Question 2

which part of the ear contains the hearing and equilibrium receptors

Answer 2

internal ear

Question 3

what is the name given to the shell-shaped projection surrounding the opening of the external auditory canal? It is composed of elastic cartilage covered with thin skin and an occasional hair.

Answer 3

Pinna (Auricle) - this is the ear

Question 4

what is the name of the structure of the ear that is a short, curved tube that extends from the auricle to the eardrum

Answer 4

the auditory canal

Question 5

what three structures make up the external ear

Answer 5

the pinna (auricle)
external auditory canal
tympanic membrane (eardrum)

Question 6

what is the structure of the ear that is a thin, semitransparent partition between the external auditory canal and the middle ear

Answer 6

eardrum, or tympanic membrane

Question 7

where is the middle ear located

Answer 7

in the temporal bone

Question 8

what resides at the most outer (lateral) wall of the middle ear

Answer 8

the tympanic membrane (eardrum)

Question 9

what does the most inner (medial) border of the middle ear consist of

Answer 9

a thin bony plate with two small openings: the oval and the round windows.

Question 10

what are the three tiny bones found in the middle ear

Answer 10

Auditory Ossicles:

• maleus (the hammer)
• incus (the anvil)
• stapes (the stirrup)

*the “handle” of the “hammer” is connected to the tympanic membrane.

Question 11

what are the two small skeletal muscles which are attached to the ossicles

Answer 11

• tensor tympani

- stapedius muscle

Question 12

the tensor tympani is innervated by the _____ branch of which CN?

Answer 12

mandibular branch of CN V (trigeminal)

Question 13

what is the function of the tensor tympani

Answer 13

it limits movement and increases tension on the eardrum to prevent damage to inner ear from loud noises

Question 14

the stapedius muscle is innervated by which CN?

Answer 14

CN VII (facial)

Question 15

what is the smallest muscle in the body

Answer 15

the stapedius muscle

Question 16

what is the function of the stapedius muscle

Answer 16

by dampening large vibrations of the stapes due to loud noises, it protects the oval window, but also decreases sensitivity of hearing.

Question 17

hyperacusia

Answer 17

hypersensitivity of hearing which occurs when there is paralysis of the stapedius muscle

Question 18

how does the middle ear communicate wit the nasopharynx

Answer 18

via the auditory (pharyngotympanic) or Eustachian tube.
it is normally closed at the pharyngeal pole, however during yawning/swallowing, it becomes open to allow air to enter/exit the middle ear until pressure in the middle ear is equal with the atmospheric pressure.

Question 19

describe the inner ear

Answer 19

aka labyrinth; canal/net-like structure; consists of bony outer labyrinth and membranous inner labyrinth.

Question 20

the inner ear is divided upon three portions. what are they?

Answer 20

• semicircular canals
• vestibule
• cochlea

Question 21

which parts of the inner ear contain receptors for equilibrium

Answer 21

semicircular canals and the vestibule

Question 22

which part of the inner ear contains receptors for hearing

Answer 22

the cochlea

Question 23

the bony labyrinth is lined with _____

Answer 23

periosteum

Question 24

what is the fluid similar to CSF that flows between the bony and membranous labyrinth

Answer 24

perilymph

Question 25

inside the membranous labyrinth, there is a flow of _____. what is this fluid’s importance?

Answer 25

endolymph; this fluid contains an unusually high level of potassium ions (K+), and potassium plays a role in the generation of auditory signals.

Question 26

The membranous labyrinth in the vestibule contains two small structures: _____ and _____. They are filled with _____. Each contains sensory epithelium: _____ _____ and _____ _____.

Answer 26

utricle; saccule; endolymph; macula utriculi and macula sacculi.

Question 27

projecting from the vestibule are three bony semicircular canals. they are called:

At one end of each canal is a swollen enlargement called:

Answer 27

anterior, posterior and lateral semicircular canal, based on their orientation

ampulla

Question 28

the portions of the membranous labyrinth that lie inside the bony semicircular canals are called:

they communicate with:

Answer 28

semicircular ducts

the utricle of the vestibule

Question 29

CN VIII (vestibulocochlear) has cochlear (auditory) and vestibular (equilibrium) portions. what nerves are found in the vestibular portion?

the axons in this portion consist of:

the cell bodies of the sensory neurons are located in the _____ _____

Answer 29

ampullary, utricular, and saccular nerves.

first order sensory neurons and axons of motor efferent neurons for equilibrium.

vestibular ganglia

Question 30

the cochlea spirals around a central core called the:

Answer 30

modiolus

Question 31

what are the three channels the cochlea is divided into

Answer 31

• scala vestibuli
• scala tympani
• cochlear duct/scala media

Question 32

of the three channels of the cochlea, which enclose perilymph and which enclose endolymph

Answer 32

the scala vestibuli and the scala tympani enclose perilymph, and the cochlear duct encloses endolymph

Question 33

what is the name of the opening at the apex of the cochlea?

which two cochlear channels communicate here?

Answer 33

helicotrema

scala vestibuli and scala tympani communicate here

Question 34

the scala vestibuli is the opening to the _____

Answer 34

vestibule

Question 35

the vestibular membrane separates the _____ _____ from the _____ _____

Answer 35

cochlear duct from the scala vestibuli

Question 36

the _____ _____ separates the scala tympani from the cochlear duct

Answer 36

basilar membrane

Question 37

the _____ _____ _____ _____ is resting on the basilar membrane and contains about 16,000 hair cells and supporting cells

Answer 37

spiral organ of corti

Question 38

each hair cell has a tip of hair bundle (hair cilia) which are bathed in:

Answer 38

endolymph

Question 39

where are cell bodies for the hearing sensory neurons located

Answer 39

in the spiral ganglion

Question 40

the _____ membrane covers the hair cells like a roof. Movement of this membrane produces movement of the cilia, which in turn triggers:

Answer 40

tectorial membrane

depolarization of hair cells

Question 41

describe the auditory pathway

Answer 41

first order sensory neurons (spiral ganglion —> cochlear branch of CN VIII) —>cochlear nuclei in the medulla oblongata (same side) and superior olivary nuclei in the pons (both sides) —> inferior colliculi in the midbrain (second order neurons) —> medial geniculate body of the thalamus (3rd order neurons) —> primary auditory cortical area in the superior temporal gyrus (41, 42) receive impulses from both sides.

Question 42

describe the equilibrium pathway

Answer 42

sensory receptors (hair cells) of two maculae —> vestibular neuron bodies in vestibular ganglia (first order neurons) —> vestibular axons of CN VIII —> vestibular nuclei of the medulla and pons (second order neurons) —> cerebrum and cerebellum.
Also, axons from all vestibular nuclei extend motor fibers to CN III, VI, and XI to control movement of the eyes, head and neck.
In addition, axons from vestibulospinal tract control tone of the skeletal muscles in response to the head movement.