Week 6 - The Ear

Question 1

external ear

Answer 1

consists of the auricle (pinna), external auditory canal, and tympanic membrane

Question 2

auricle (pinna)

Answer 2

flap of cartilage on the outside of the head; collects and transmits sound waves to middle ear

Question 3

external auditory canal (external acoustic meatus)

Answer 3

tube in the temporal bone; ear wax produced by ceruminous glands; hairs and ear wax in external auditory canal prevent foreign materials entering ear

Question 4

tympanic membrane

Answer 4

fibrous connective tissue; separates external and middle ear; vibrates in response to sound

Question 5

middle ear

Answer 5

small, air-filled cavity in the temporal bone;
5 openings: tympanic membrane, oval window, round window, pharyngotympanic tube (auditory tube) (Eustachian tube), mastoid cavity;
ear ossicles (connected to ligaments and two small muscles: malleus, incus, stapes

Question 6

malleus (hammer)

Answer 6

attached to the tympanic membrane

Question 7

incus (anvil)

Answer 7

in the middle

Question 8

stapes (stirrup)

Answer 8

fits over the oval window

Question 9

functions of the middle ear

Answer 9

1. transmits vibrations to the inner ear
2. provides protection to prolonged loud noises by decreasing the sensitivity of hearing – done by the small skeletal muscle around the ossicles
3. equalizing air pressure on both sides of the tympanic membrane via the Eustachian tube – prevents pain, hearing impairment, ringing in ears, vertigo

Question 10

middle ear infection: otitis media

Answer 10

may develop after a throat infection or cold; the nasopharynx is linked to the middle ear through the pharyngotympanic tube; pathogens in the throat can travel up the tube and cause middle ear infections (otitis media)

Question 11

inner ear

Answer 11

consists of bony labyrinth and membranous labyrinth

Question 12

bony labyrinth

Answer 12

channels running through the temporal bone; contains the vestibule (equilibrium), the cochlea (hearing), and the semicircular canals (equilibrium); filled with perilymph (similar to cerebrospinal fluid)

Question 13

membranous labyrinth

Answer 13

series of membranous sacs within the bony labyrinth; filled with a K+ rich fluid called endolymph

Question 14

cochlea: cross section

Answer 14

-a spiral, conical bony chamber that extends from the anterior vestibule and contains the organ of Corti (hearing receptor)
-divided into three chambers: Scala vestibuli, Scala media, Scala tympani

Question 15

cochlea: longitudinal section

Answer 15

-the Scala vestibuli begins at oval window
-the Scala tympani terminates at round window
-the Scala tympani and Scala vestibuli are filled with perilymph and continuous with each other via the helicotrema
-the Scala media (cochlear duct) is filled with endolymph

Question 16

organ of Corti

Answer 16

outer and inner hairs and supporting cells; afferent fibers of the cochlear nerve attach to the base of hair cells; the stereocilia are embedded in the tectorial membrane

Question 17

sound

Answer 17

a pressure disturbance originating from a vibrating object; represented by a sine wave in wavelength, frequency, and amplitude

Question 18

short wavelength

Answer 18

= high frequency = high pitch