lect 9- Auditory Senses

Question 1

describe the conduction pathway sequence (auditory)

Answer 1

tympanic membrane –> malleus –> incus –> stapes –> oval window

Question 2

what does the malleus articulate with

Answer 2

the anvil (incus)

Question 3

what does the malleus attach to

Answer 3

tympanic membrane

Question 4

describe the incus (anvil)

Answer 4

intermediate bone between the stapes and the malleus; the name “incus” refers to an anvil, on which the hammer (malleus) strikes

Question 5

what is the third bone in the series in the middle ear

Answer 5

stapes

Question 6

what does the stapes insert onto

Answer 6

oval window

Question 7

what does the oval window open into

Answer 7

scala vestibuli

Question 8

where is the round window located

Answer 8

at the end of the scala tympani

Question 9

what does the tensor tympani do

Answer 9

inserts on the malleus and pulls handle of malleus inward

Question 10

what does the stapedius muscle do

Answer 10

inserts on the stapes and pulls stapes outward

Question 11

when do the muscles of the middle ear contract

Answer 11

contract reflexively in response to loud sounds in order to dampen the vibrations of the auditory ossicles

Question 12

what provides the impedance matching between the air and the fluid

Answer 12

the tympanic membrane and auditory ossicles

Question 13

what are the major components of the cochlea

Answer 13

scala vestibuli, scala media, scala tympani and reissner’s membrane

Question 14

what separates scala medial from scala vestibuli

Answer 14

Reissner’s membrane (vestibular membrane)

Question 15

what does the basilar membrane separate

Answer 15

separates scala media from scala tympani

Question 16

describe the basilar fibers

Answer 16

length increases from the oval window to the apex of the cochlea (helicotrema) and diameter of the fibers decrease from oval wind to the apex of the cochlea

Question 17

what is the result of the different tights of fiber distribution in basilar fibers

Answer 17

still, short fibers near the oval window beat at a high frequency; long, limber fibers near the apex of the cochlea vibrate at a low frequency

Question 18

what does the organ of corgi generate nerve impulses in response to

Answer 18

vibration of basilar membrane

Question 19

what type of cells are the sensory receptors of the organ of corti

Answer 19

hair cells

Question 20

what creates the rigid unit of the organ of corti

Answer 20

outer ends of hair cells are tightly attached to reticular lamina, supported by rods of corgi, which are attached to the basilar fibers.

Question 21

what cranial nerve is involved with the organ of corti

Answer 21

CN 8: cochlear nerve

Question 22

what does movement of the basilar fibers cause movement in

Answer 22

reticular lamina

Question 23

what happens to hair cells when the basilar membrane moves

Answer 23

hair cells become excited

Question 24

what is the scala media filled with

Answer 24

endolymph

Question 25

what is the scala vestibule filled with

Answer 25

perilymph

Question 26

what is the scala tympani filled with

Answer 26

perilymph

Question 27

describe the concentrations of potassium and sodium in the endolymph

Answer 27

high concentrations of potassium and low concentration of sodium (perilymph is the opposite)

Question 28

what is the different in mV between endolymph and perilymph and what is this called

Answer 28

called the endocochlear potential and is +80mV

Question 29

what is the intracellular potentials of hair cells with respect to perilymph and endolymph

Answer 29

perilymph: -70mV
endolymph: -150 mV

Question 30

define place principle

Answer 30

nervous system detects frequencies by determining positions along the basilar membrane that are most stimulated

Question 31

list the components of the nervous system pathway (in order):

Answer 31

spiral organ of corgi, dorsal and ventral cochlea nuclei, superior olivary nucleus, lateral lamniscus nucleus, medial geniculate nucleus (thalamus), auditory cortex