Lab 9

Question 1

What are the muscles of the eye, what CN controls them and what direction do they pull the eye?

Answer 1

Superior Rectus: CN III, elevation
Medial Rectus: CN III, adduction (to midline)
Inferior Rectus: CN III, depression
Inferior Oblique: CN III, elevation when eye is adducted
Superior Oblique: CN IV, (its only function), depression when eye is adducted
Lateral Rectus: CN VI (its only function), abduction of eye

Question 2

What are the external structures of the eye and what do they do?

Answer 2

Conjunctiva: covers sclera, transparent membrane containing capillaries (inflammation: pink eye or conjunctivitis)
Cornea: transparent dome covering iris/pupil, bends light a little
Sclera: white part because it is made of connective tissue, it is an attachment point for muscles and allows the eye to maintain its shape
Iris: Pigment area of the eye, smooth muscle, changes size of hole to control the amount of light entering the eye
Pupil: the hole in the middle of the iris

Question 3

How do you orientate the eye?

Answer 3

Lacrimal gland is lateral
Lacrimal sac or nose is medial

Question 4

What are the internal structures of the eye?

Answer 4

Lense: bends light more to hit areas in the eye
Ciliary muscle changes the shape of the lens - curves or flattens
Ciliary body: scallopy circular structure
Choroid: Blood supply to the inside of eye, contains a lot of melanin making it dark so it absorbs light to prevent bouncing
Retina: Nervous tissue containing light receptor cells
Macula Lutea: Most cones of the retina making it an extra dark circle
Fovea centralis: Greatest concentration of cones- divot in macula lutea
Optic disk: where nerve attaches to the retina allowing for no photoreceptors causing a blind spot
Optic Nerve: CN II

Question 5

What are the spaces of the eye?

Answer 5

The anterior chamber between the lens and the cornea filled with loose watery fluid called aqueous humor
The posterior chamber between the lens and the retina filled with thick fluid called vitreous humor that is never replenished or replaced and puts pressure on the retina to hold it down

Question 6

What are the light receptor cells of the retina?

Answer 6

Rods: dim light
Cones: bright light and color detection. Erythrolabes, cyanolabes, cholorolabes
Red + green = yellow
Blue + red = purple

Question 7

What was the blind spot test?

Answer 7

Look directly at X and peripherally at dot, note that with one eye open the dot finds the blind spot caused by the optic disk and “disappears,” but crossing vision fields does not allow this to happen when both eyes are open

Question 8

What was the negative after image test?

Answer 8

Look at blue star for a minute, cyanolabes tire, look at white see yellow because erythro&chlorolabes are active byt cyanolabes are not

Question 9

What are the general functions of the ear?

Answer 9

Detecting sound, your movement in space, and where you are in respect to the ground.

Question 10

What is sound?

Answer 10

Sound is the vibration of air molecules

Question 11

What are the structures of the external ear and what do they do?

Answer 11

The external ear is air filled
Pinna: focuses sound waves into the skull
External auditory canal: conducts sound from pinna through external acoustic meatus
External acoustic meatus: tunnel in the skull
Tympanic membrane: sheets of membranous tissue that completely seals the external auditory canal.

Question 12

What are the structures of the middle ear and what do they do?

Answer 12

The middle ear is air filled
Ossicles all touch each other causing vibrations to be strengthened and transmitted through the internal ear
1- Malleus 2- Incus 3- Stapes (hammer, anvil, stirrup)
Eustachian tube: releases pressure in middle ear by attaching to the nasopharynx. Flap “pops” open to release pressure

Question 13

What are the structures of the inner ear that aid in earing and what do they do?

Answer 13

The inner ear is fluid filled
Oval window: membranous, connects to stapes bringing vibrations into the fluid of the cochlea
Cochlea: snail shell containing (from superior to inferior) the vestibular duct, the cochlear duct, the organ of Corti, and the tympanic duct,

Question 14

What is the bony labyrinth and what are its structures?

Answer 14

Structures that are covered by bone and contains perilymph Cochlea, vestibule, and semicircular canal

Question 15

What are the membranous labyrinths?

Answer 15

(Blue) areas within bony labyrinth containing endolymph
Cochlear duct (in cochlea), saccule and utricle (in vestibule), and semicircular duct (in semicircular canals)

Question 16

What are the sensory organs of the membranous labyrinths and what are their receptor cells sensitive to and where does the stimulus go?

Answer 16

Organ of Corti in the cochlear duct with hair cells activated by vibrations that will stimulate the sensory neurons of the cochlear branch of CN VIII
Macula in the saccule and utricle with hair cells activated by gravity and acceleration stimulating sensory neurons in the vestibular branch of CN VIII
Ampulla at the base of the semicircular duct with hair cells activated by rotating stimulating the axons in the vestibular branch of the CN VIII

Question 17

What are the misc structures of the ear?

Answer 17

vestibular ganglion, vestibular branch of CN VIII, round window, cochlear ganglion, cochlear branch of CN VIII

Question 18

What was the Romberg test? And what structures were tested

Answer 18

Volunteer stood with feet together and hands at side first with eyes open then with eyes closed. If volunteered did not sway much they had a negative Romberg response, otherwise they had a positive Romberg response.
The vestibule with its saccule and utricle and macula sensory organ were tested.

Question 19

What was the Rinne test and what was it testing?

Answer 19

Strike tuning fork, place handle on mastoid process then hold next to ear.
Is air conduction was louder the test was positive, if bone conduction was louder the test was negative
The part of inner ear being tested was the cochlear with its cochlear duct and the organ of Corti

Question 20

What is not vibrating correctly when an individual has an ear infection?

Answer 20

The ossicles