Part3

Question 1

What is the fiber pattern layout?

Answer 1

The more peripheral the origin of a nerve fiber, the more external its location in the nerve fiber layer and in the optic nerve.

Question 2

How are the largest pores of the lamina cribrosa arranged?

Answer 2

Hourglass configuration superiorly and inferiorly.
Ganglion cell axons pass through these pores. THese cells are affected first in glaucoma because CT tissues suck superiorly and inferiorly.

Question 3

What are two features of the postlaminar region?

Answer 3

1. Myelination of axons from lamina cribosa to the terminal nuclei in the brain
2. The meninges surrounding the brain.

Question 4

Astrocytes

Answer 4

Glial cell that is mainly part of the prelaminar portion.

Question 5

Central caudate sub-nucleus

Answer 5

Belongs to CN III nucleus.

Is single and control both levators.

Question 6

Ed Wes nucleus is….

Answer 6

Another exception to CNIII nucleus having paired subnuclei corresponding to each muscle.
Single at one end but divided into two at its anterior end.

Question 7

What does superior division of CNIII innervate?

Answer 7

LPS and SR

Question 8

What does inferior division of CN III innervate?

Answer 8

MR, IO, IR

Question 9

Does Ed-Wes nucleus give rise to sympathetic or parasympathetic branches?

Answer 9

Parasympathetic

Question 10

Parasymp branches from CNIII is for…

Answer 10

Iris sphincter and ciliary muscle

Inferior division

Question 11

Sympathatic branches from CNIII is for….

Answer 11

Superior tarsal muscle-open up your big eyes.

Superior Division

Question 12

What does 1:3 represent?

Answer 12

The nerve to muscle fiber ratio. One nerve for every three muscles in the body.

Question 13

Are there more postganglion fibers or less preganlionic fibers for the inferior division?

Answer 13

More postganglionic fibers.

This means the system is diffuse.

Question 14

What does CN IV paralysis consist of?

Answer 14

1. Vertical squint
2. Can’t lookdown when eye is in adducted position because SO is the only depressor in the adducted position.
3. Head tilt - downward and towards the normal side to avoid diplopia.
4. The affected ye rotates medially producing diplpia when looking downwards.

Question 15

Which cranial nerve is the most vulnerable?

Answer 15

CN VI.

Any cerebral lesion no matter what distance can damage it.

Question 16

Where is the nucleus of CN VI found?

Answer 16

Floor of the 4th ventricle close to the median plane.

Question 17

What is CN VI paralysis?

Answer 17

Inability to abduct the eye beyond the straight ahead gaze.

Diplopia on looking into the direction of the affected side.

Question 18

What is the origin CN II?

Answer 18

Retinal ganglion cells.

Question 19

Layers 1 & 2 of LGN?

Answer 19

Magnocellular

Mixed ON & OFF

Question 20

Layers 3-6 of LGN?

Answer 20

Parvocellular

Question 21

Contralateral?

Answer 21

1, 4, 6

Question 22

Optic chism-crossover fibers?

Answer 22

Inferior nasal and superior nasal fibers both crossover; but the inferior nasal fibers is more lateral than the medial fibers.

Question 23

Superior temporal vs Inferior temporal

Answer 23

Both will stay on the ipsilateral side of the eye; but the Superior temporal will be more medial.

Question 24

Where are the macular fibers located in the optic tract?

Answer 24

Located in between.

Question 25

What is the preganglion neuron location for the SNS?

Answer 25

Lateral horn of spinal cord

Question 26

What is the postganglion neuron location for SNS?

Answer 26

Superior cervical ganglion.

Question 27

How do SNS fibers enter the eye?

Answer 27

Short ciliary nerves Long ciliary nerves Rami oculares Blood vessels.

Question 28

What are the orbital distribution of SNS fibers?

Answer 28

Lacrimal gland (blood vessels) Superior & Inferior tarsal muscles Orbital muscle of Mueller Orbital blood vessels.

Question 29

What is the ocular distribution of SNS fibers?

Answer 29

``` Dilator M. Sphincter M. Ciliary M. Ocular blood vessels Trabeculum ```

Question 30

What do CN III and VII have in common?

Answer 30

Both have PNS innervation

Question 31

Where is the preganglionic neuron for CN III located?

Answer 31

CN III nucleus (midbrain, sup collic)

Question 32

Where is the preganglionic neuron for CN VII located?

Answer 32

CN VII nucleus (pons-middle)

Question 33

Where is the postganglionic neuron for CN VII located?

Answer 33

Pterygopalatine ganglion

Question 34

Where is the postganglionic neuron for CN III located

Answer 34

Ciliary ganglion

Question 35

How does PNS fibers enter the eye?

Answer 35

Short ciliary Nerves (CN III) Rami Oculares (CN VII) This differs from SNS which has 4.

Question 36

What are the orbital distribution of PNS?

Answer 36

``` Similar to SNS minus the Mueller muscles. Have: Lacrimal gland Superior & Inferior tarsal muscle Blood vessels ALl of these is from CN VII ```

Question 37

What are the ocular distribution of PNS

Answer 37

Same as SNS

Question 38

What are the three actions that result from corneal reflex?

Answer 38

Miosis Lacrimation Blinking

Question 39

Disruption of the sympathetic pathway?

Answer 39

Horner's syndrome

Question 40

Symptoms of Horner's syndrome

Answer 40

Miosis: usual tone for dilator muscle is gone Anisocoria: pupil constriction for affected eye Anhidrosis: absense of sweat secretion

Question 41

What cells of the iris form the iris stroma and anterior border layer?

Answer 41

Fibroblasts and melanocytes that derived from neural crest cells. Early layer of cells is known as the pupillary membrane.

Question 42

How do the anterior and posterior epithelial layers of the iris come about?

Answer 42

two layers of cells on top of the optic cup multiply and grow inward beneath the stroma.

Question 43

T/F? | Pupil is the last structure to be formed.

Answer 43

True. Ant and post epi cells do not grow in the center. The iris stroma needs to be removed around this central region or the epithelial free zone.

Question 44

Where are the sphincter pupillae and dilator pupillae muscle formed from?

Answer 44

From the anterior epithelium. Neuroectoderm origin Sphincter develops before dilator

Question 45

Iris blood vessels

Answer 45

Branches of major arterial circle forming in the developing ciliary body. Mesodermal origin.

Question 46

How do choroidal capillaries first appear?

Answer 46

At the posterior pole and then differentiate peripherally.

Question 47

Talk about choroidal circulation?

Answer 47

Choriocapillaris forms first (around 2 months), then the short posterior ciliary arteries (Haller's and Sattler's) are added to supply choriocapillaris. Pt 2: long posterior ciliary arteries bypass developing choroid and contribute to circulation in anterior aspect of eye. 1. Tunica vasculosa lentis 2. Annular vessel 3. Major arterial circle 4. Intramuscular arterial circle.