Lec 20 The Ear & Eye

Question 1

What is the purpose of the tympanic membrane? (eardrum)

Answer 1

separates outer ear from middle ear

Question 2

what 3 layers is the tympanic membrane composed of?

Answer 2

outer - modified skin
middle - fibrous layer
inner - mucous layer

Question 3

pulled posteriorly & superiorly; translucent enough to see mallelus attached to inner surface.

These are qualities of the.. ?

Answer 3

tympanic membrane

Question 4

what is the middle ear composed of?

Answer 4

tympanic cavity
auditory (eustachian tube)
ossicles

Question 5

what is the eustachian tube?

Answer 5

where middle ear is connected to the nasopharynx.

horizontal in child but slowly becomes more vertical in adult. (which is why in a child, bacteria can easily travel from naso to middle ear)

Question 6

what are 3 forms of ossicles?

Answer 6

mallelus - attached to tympanic membrane
incus - interposed between mallelus and stapes
stapes - inserted into oval window of inner ear

Question 7

where is the inner ear located?

Answer 7

temporal bone

Question 8

where are receptors for hearing and equilibrium located?

Answer 8

special structures in the inner ear

Question 9

what parts do the inner ear divide into?

Answer 9

cochlea, vestibule, and semicircular canals

Question 10

what is equilibrium also influenced by, other than the vestibular apparatus?

Answer 10

impulses from the spinal cord and cerebellum.

information coming from visual stimuli and receptors of muscles and tendons.

Question 11

what is the structure of a cochlea?

Answer 11

connection of tubes and sacs

Question 12

What does the vestibular apparatus sense?

Answer 12

equilibrium. hair creates electrical impulse.

Question 13

what is the difference between endolymph and perilymph?

Answer 13

endolymph = internal fluids in membranous labyrinth.

perilymph = “surrounding water”. fluid in bony labyrinth.

Question 14

which structures make up the inner ear?

Answer 14

cochlea
vestibule
semicircular canals

Question 15

what are the organ of Corti?

Answer 15

Hair cells, receptor epithelium for hearing

Question 16

what is the purpose of the vestibulocochlear nerve? (CNVIII)

Answer 16

transmits impulses from hearing and equilibrium receptors to appropriate areas of the brain for interpretation

Question 17

what is the auditory pathway?

Answer 17

cochlear division of CN VIII -> nucleus of VIII in medulla -> thalamus -> auditory cortex of temporal lobe.

Question 18

what is the conjuctiva?

Answer 18

a transparent mucous membrane that covers the inner surfaces of the eyelids

Question 19

what is the lacrimal gland?

Answer 19

produces lacrimal fluid. Blinking spreads this fluid across the eyeball

Question 20

what is the sclera?

Answer 20

“the white of the eye”

protects eyeball and provides shape and anchoring for eye muscles.

Question 21

what is the iris?

Answer 21

colored part of eye

Question 22

what is the retina?

Answer 22

inner layer that contains pigmented layer and thick neutral layer.

Question 23

what is the aqueous humor?

Answer 23

(aqueous = watery)
clear fluid similar to blood plasma.
renewed constantly, is in constant motion.

Question 24

what is the vitreous humor?

Answer 24

(vitreus = glassy)

jellylike substance that contains collagen and ground substance that binds water

Question 25

what is the lens?

Answer 25

thick, transparent disc that changes shape to allow precise focusing of light on the retina.

Question 26

what are rods and cones?

Answer 26

rods = sensitive to light, permit vision in dim lighting
cones = operate best in bright light.