Unit 1 - C.N. II - Optic Nerve

Question 1

Outermost layer of the eye

Answer 1

Fibrous tunic

Question 2

The fibrous tunic consists of what two things?

Answer 2

Sclera and cornea

Question 3

What is the only part that goes completely around the eye?

Answer 3

sclera

Question 4

What is the middle layer of the eye?

Answer 4

Vascular tunic

Question 5

What are the three parts of the vascular tunic?

Answer 5

Ciliary body, Iris, choroid

Question 6

Why is the vascular tunic not complete?

Answer 6

Because of the Iris - has a pupil

Question 7

What is the innermost layer of the eye?

Answer 7

The retina

Question 8

What layer is adjacent to the choroid?

Answer 8

Pigmented layer (cementing layer)

Question 9

What is the next layer inward after the pigmented layer?

Answer 9

Photosensitive outer segments of rods and cones

Question 10

What layer covers the rods and cones?

Answer 10

External limiting membrane

Question 11

What layer contains the cell bodies of rods and cones?

Answer 11

Outer nuclear layer

Question 12

Rods and cones synapse with bipolar cells here.

Answer 12

Outer Plexiform layer

Question 13

Layer that contains the cell bodies of bipolar cells?

Answer 13

Inner nuclear layer

Question 14

Layer where bipolar cells synapse with ganglion cells?

Answer 14

Inner plexiform layer

Question 15

Layer of ganglion cell bodies?

Answer 15

Ganglion cell layer

Question 16

Are retinal ganglion cell axons myelinated?

Answer 16

no

Question 17

Layer containing the ganglion cell bodies?

Answer 17

Ganglion cell layer

Question 18

Layer containing the retinal ganglion cell axons?

Answer 18

Nerve fiber layer

Question 19

A glial boundary separating the retina from the vitreous body?

Answer 19

Internal limiting membrane

Question 20

Name the layers from 1 -10 (choroid to vitreous body)

Answer 20

Pigmented layer
Photosensitive outer segments of rods and cones
External limiting membrane
Outer nuclear layer
Outer plexiform layer
Inner nuclear layer
Inner plexiform layer
Ganglion cell layer
Nerve Fiber layer
Internal limiting membrane

Question 21

What is the distal end of the photoreceptor called?

Answer 21

The outer segment

Question 22

The outer segment of the photoreceptor is closes to what?

Answer 22

The choroid

Question 23

The outer segment of the photoreceptor has two shapes. What are they?

Answer 23

Cylindrical (rod shaped) and tapered (cone shaped)

Question 24

There are three types of cones that receive information, they are?

Answer 24

Red, green, and blue

Question 25

What is required for the cones to work?

Answer 25

Light

Question 26

Where are the cones more concentrated?

Answer 26

Toward center of the retina (fovea)

Question 27

What are the only thing rods sense?

Answer 27

Light and dark (only shades of grey)

Question 28

Are there rods in the fovea?

Answer 28

NO

Question 29

What is the periphery of the retina completely composed of?

Answer 29

rods

Question 30

When depolarized, photoreceptors relay information to bipolar cells by synapsing in what layer?

Answer 30

Outer plexiform layer

Question 31

Axons from ganglion cells are coveted in the nerve fiber layer toward the _____.

Answer 31

Optic disc

Question 32

Where does the optic nerve attach to the eye?

Answer 32

Optic disc

Question 33

Where are the axons from nerve fiber layer carried in outside of the eye?

Answer 33

In the optic nerve

Question 34

Are ganglionic cells myelinated?

Answer 34

no

Question 35

When do the axons of the ganglion cells become myelinated?

Answer 35

When they leave the eye

Question 36

The optic nerve enters the skull through the _____ and unites to form the ______.

Answer 36

Optic canal | Optic chiasma

Question 37

Are optic nerve fibers myelinated?

Answer 37

yes

Question 38

What cells form the myelination of the optic nerve?

Answer 38

(interfasicular) oligodendrocytes

Question 39

In the optic chiasma which fibers cross?

Answer 39

Fibers from the medial (nasal) side of the retina

Question 40

In the optic chiasma which fibers do not cross?

Answer 40

Fibers from the lateral (peripheral) side of the retina

Question 41

The optic tract travels around what?

Answer 41

Cerebral peduncles

Question 42

After traveling around the cerebral peduncles, the optic tract fibers synapse which three nuclei of termination?

Answer 42

Lateral geniculate body Superior colliculus pretectal nucleus of the midbrain

Question 43

The majority of optic tract fibers synapse in which N.O.T.?

Answer 43

Lateral geniculate body

Question 44

After synapsing in the lateral geniculate body, where is the information relayed?

Answer 44

The cerebral cortex in the occipital lobe (B.A. 17)

Question 45

After synapsing in the superior colliculus, where is the information relayed to?

Answer 45

The tectospinal tract

Question 46

What are the two muscles influenced by the tectospinal tract?

Answer 46

trapezius | sternocleidomastiod

Question 47

Fibers from rods/cones to SCM/trapezius arrive via what nerve?

Answer 47

C.N. XI - accessory nerve

Question 48

The tectospinal tract goes down to what level of the spine?

Answer 48

C4

Question 49

How many neurons are in the optic pathway?

Answer 49

3 - photoreceptor to bipolar to ganglionic

Question 50

Colorblindness is most common in _____?

Answer 50

males

Question 51

Most colorblindness is sex-linked on which chromosome?

Answer 51

X

Question 52

Optic nerve lesion causes?

Answer 52

Loss of depth perception, decrease in size of visual field (

Question 53

Decussating fibers of the optic chiasma causes?

Answer 53

tunnel vision, lose peripheral vision

Question 54

What passes through the optic chiasma that can lead to tunnel vision?

Answer 54

infundibular stalk, so a pituitary lesion can cause

Question 55

Lesion of the optic tract causes?

Answer 55

One side of vision is gone (opposite side of lesion)

Question 56

Which 3 visual reflexes test C.N. II - sensory/afferent only?

Answer 56

Direct and consensual reflexes Accommodation reflex Corneal reflex

Question 57

How do you test direct and consensual reflexes?

Answer 57

Shine light in L eye and swing light back and forth. Direct = L pupil constricts Consensual = R pupil slightly constricts

Question 58

What is the accommodation reflex?

Answer 58

Changing the shape of the lens to focus near and far

Question 59

How do you test convergence?

Answer 59

Use a pen and move pen towards patient's nose. Eyes should coverage and track in.