Orbit

Question 1

Where do lower motor neurons of the ventral horn of the spinal cord terminate?

Answer 1

on muscles

-so even the cells terminating on the eye muscles are lower motor neurons

Question 2

Retinal gangilion cells of the retina project to the ____, ____, ____ via the optic nerves and tracts

Answer 2

• SCN
• SC
• LGN

Question 3

The LGN of the thalamus projects to the _________ via the optic radiations

Answer 3

• primary visual cortext (VI)

Question 4

VI (Striate cortex) is found in the _____ lobe along the banks of ______

Answer 4

• VI striate cortex is found in the occipital lobe along the banks of the calcarine fissure

Question 5

Light enters the eye and via the pupil and is focused on the retina via the _____

Answer 5

Lens

Question 6

The initial processing of information occurs in the _____

Answer 6

Retina

Question 7

What part of the eye contains the highest concentration of cones and is where the finest visual discrimination occurs

Answer 7

The fovea within the macula

Question 8

Where do the axons of the ganglion cell exit the retina

Answer 8

Optic disc

Question 9

What are the cells that give rise to the optic nerve?

Answer 9

retinal ganglion cells

Question 10

The axons of the ganglion cells leave the retina at the _____

Answer 10

Optic disc

• no photoreceptors here, so this is a blind spot

Question 11

Label these layers of this retina

Answer 11

Question 12

Why is there pigemented epithelium in the retina?

Answer 12

• think of photons as particles
• you do not want these particles bouncing around so you want them to be absorbed by something incase they miss a photoreceptor cell
• you will have very blurry vision if you didnt have this
• albinos do not have pigemented epithelium

Question 13

Where are the horizontal cells, bipolar cells and amcrine cells located?

Answer 13

in the INL

inner nuclear layer

Question 14

Where are the cell bodies of rods and cones located?

Answer 14

ONL

Outer nuclear layer

Question 15

Where are the cell bodies of ganglion cells?

Answer 15

GCL

Ganglion cell layer

Question 16

Where is the outer segment located in the retina?

Where is the nucleus located?

Where is the synaptic body located?

Answer 16

Outer segment: PL photoreceptor layer

nucleus: ONL outer nuclear layer

Synaptic body: OPL outer plexiform layer

Question 17

How many different types of rods and cones are there?

Answer 17

one type of rod

3 types of cones

each has a distinctive response to different wave lengths

Question 18

If you have lesion of the optic nerve after the chiasm (in the optic tract) will you have loss of a visual field?

Answer 18

Yes the contralateral side

Question 19

Which ganglion cell axons cross at the optic chiasm?

from the nasal or from the temporal?

Answer 19

• ganglion cell axons originating from the nasal retina cross at the optic chiasm to the contralateral side
• ganglion cell axons from the temporal retina do not cross at the optic chiasm and remain ipsilateral

Question 20

The axons originating from the retinal ganglion cells which terminate in the superior colliculus form the ______

Answer 20

• the axons originating from the retinal ganglion cells which terminate in the superior colliculus form the brachium of the superior colliculus in close proximity to the superior colliculus

Question 21

Where do the retinal ganglion cells project to?

Answer 21

1. Suprachiasmatic nucleus of the hyothalamus (circadian pacemaker
2. Pretectal nuclei (eye movements)
3. Superior colliculus (visual reflex)
4. Lateral geniculate nucleus of the thalamus

Question 22

The superior colliculus (of the midbrain) receives direct retinal input via the ________

Answer 22

Brachium of the superior colliculus

Question 23

The superior colliculus receives input from:

Answer 23

1. brachium of the superior colliculus
2. visual cerebral cortex
3. pretectal nuclei

Question 24

the superior colliculus is involved in:

Answer 24

visual reflexes

Question 25

the superior colliculus projects to the spinal cord via the

Answer 25

tectospinal tract

Question 26

The lateral geniculate nucleus (LGN) is located in the \_\_\_\_

Answer 26

Thalamus of the diencephalon

Question 27

The LGN receives direct retinal input via the

Answer 27

Optic tract

Question 28

The LGN projects to the _____ via the \_\_\_\_\_

Answer 28

Primary visual cortex (area 17) via the optic radiations

Question 29

With these lesions what is your deficit?

Answer 29

Question 30

A protective, thin, transparent mucous membrane that has two parts:

Answer 30

Conjuntvia: * palpebral * bulbar (ocular)

Question 31

Which layer of the conjunctiva lines the innermost part of the eyelids?

Answer 31

* palpebral conjunctiva

Question 32

Which layer of the conjunctiva lines the outermost part of the eyeball?

Answer 32

Bulbar (ocular) conjunctiva

Question 33

Inflammation of the conjunctiva is commonly called

Answer 33

Pink eye

Question 34

Explain the corneal reflex

Answer 34

1. Afferent: nasociliary branch of the opthalmic branch of the trigeminal nerve (V1) sensing the stimulus on the cornea 2. Efferent: facial nerve (zygomatic branch) initiating the motor response of the orbicularis oculi

Question 35

Name this layer of the eye: * dark reddish brown membrane between the sclera and the retina * largest part of the vascular layer-all arteries feeding choroid are branches from opthalmic artery * lines majority of the sclera * "red eye" in pictures

Answer 35

Chorioid * choriocapillaries nourish the outermost (cones and rods) layer of retina

Question 36

What is the circumferential tissue inside the eye composed of the ciliary muscles and processes * vascular layer

Answer 36

Ciliary body

Question 37

What secretes aqueous humor which fills the anterior and posterior chambers of the eye * nourishes lens and cornea because they are avascular

Answer 37

Ciliary processes

Question 38

What is the space between cornea and the iris/pupil?

Answer 38

* anterior chamber

Question 39

What is the space between the iris/pupil and the lens and ciliary body?

Answer 39

Posterior chamber

Question 40

Explain the flow of aqueous humor:

Answer 40

* goes to posterior then anterior chamber * then drains in vein of sclera

Question 41

Blockage of schlemm's canal (sclera venous sinus) can lead to increased pressure and \_\_\_\_?

Answer 41

Glaucoma

Question 42

What is the adjustment in the len's shape to focus at various distances * under PARAsympathetic control * contaction = release of tension = spherical lens = close vision

Answer 42

Accomodation

Question 43

What is this vascular layer of the eye? * colored circular muscle * a central aperature-the pupil- for transmitting light

Answer 43

Iris vascular layer

Question 44

What muscle: * parasympathetic via ciliary ganglion * closes the pupil * "constriction"

Answer 44

Sphincter pupillae muscle

Question 45

What muscle: * sympathetic via superior cervical ganglion * opens the pupil

Answer 45

DIlator pupillae muscle

Question 46

Discuss eyeball movements

Answer 46

Question 47

Discuss agonists, synergists, and antagonists

Answer 47

Question 48

How is testing eye muscles individually with the H test different from their actions in a straight ahead gaze?

Answer 48

* muscles rarely act independently and almost always work together in syngergist and antagoist groups * thus, clinical testing requires maneuvers to isolate muscle actions * only the actions of the medial and lateral rectus are tested, starting from the primary postion * the others must be tested either from an abducted or adducted postion * When the eye is aBducted by the lateral rectus, only the rectus muscles can produce elevation and depression * When the eye is aDducted by the medial rectus, only the oblique muscles can produce elevation and depression

Question 49

Which nerve of the eye has parasympathetic fibers?

Answer 49

Oculomotor nerve (CN III)

Question 50

Explain oculomotor nerve palsy

Answer 50

Question 51

What muscle is innervated by trochlear nerve (CN IV)?

Answer 51

Superior Oblique

Question 52

What muscle is innervated by abducent nerve (CN VI)?

Answer 52

Lateral Rectus m

Question 53

Describe abducent nerve palsy

Answer 53

Lateral rectus is gone so medial rectus is pulling with no opposition * but in B we were able to move it out of abduction * Sherings Law * we inhibit antagonist because brain is still trying to get the eye to move to abduction * so the brain inhibits medial rectus for us and we can move the eye to the middle but still cant abduct

Question 54

Describe the fibers running through the ciliary ganglion

Answer 54

Pass through ganglion without synapsing

Question 55

Describe Horner's sydrome

Answer 55

* Results from interruption of a cervical sympathetic trunk and is manifest by the absence of sympathetically stimulated functions of the ipsilateral side of the head 1. Constriction of pupil (miosis)-because dialators are knocked out 2. Drooping of superior eyelid (ptosis)-tone is gone 3. Sunken in eye (enopthalmos) 4. redness and increased temperature of skin (vasodialation) 5. absense of sweating (anhydrosis)

Question 56

What are the two arteries that supply extraocular muscles and what specifically do they supply?

Answer 56

Opthalmic artery: * branch of internal carotid * the opthalmic artery supplies most of the extraocular structures Infraorbital artery: * branch of external carotid artery * the infraorbital artery supplies the lower portion (floor) of the orbit

Question 57

Where do the presynaptic fibers of of sympathetic synapse?

Answer 57

* Superior cervical ganglion * some fibers run with opthalmic all the way to the bulb via long ciliary * other run through ciliary ganglion and pass to bulb via short ciliary nerves

Question 58

Where do the presynaptic fibers of parasympathetic synapse with postsynaptic nucleus?

Answer 58

* Ciliary ganglion

Question 59

What does contraction of the ciliary muscles do?

Answer 59

* Causes the circular ciliary body to decrease in diameter * like a sphincter, the lens relaxes, rounding up or thickening (near vision) * accommodation * if you relax the ciliary body this increases its diameter * thus the lens suspended in its center is stretched and become thinner (far vision)

Question 60

What nerve does the corneal reflex? * touching cornea with wisp of cotton envokes blink

Answer 60

Opthalmic nerve V1