CN 3, 4, 6

Question 1

bones of the orbit

Answer 1

Orbit margin:

1) frontal**
2) zygomatic**
3) maxilla**

Inner orbit:

4) sphenoid
5) ethmoid
6) palatine
7) lacrimal

Question 2

tarsus plates

Answer 2

thick CT barrier for protection that allow you to flip your eyelids inside out

Question 3

conjunctiva

Answer 3

vascular layer on top of sclera (innermost of eyelid and outermost of eyeball)

• protective, thin, transparent mucous membrane with two parts that are continuous with each other
  1) palpebral conjunctiva
  2) bulbar (ocular) conjunctiva

Question 4

what are and describe the two part of conjunctiva?

what is between the layers?

Answer 4

1) palpebral conjunctiva
- – lines the innermost part of the eyelids
2) bulbar (ocular) conjunctiva
- – lines the outermost past of the eyeball

*** conjunctival sac

Question 5

what are the glands found in the eyelid?

Answer 5

sebaceous

modified apocrine glands

Question 6

what do the eyelid glands produce?

Answer 6

sebum to prevent eyelids from sticking

Question 7

describe sebum

Answer 7

oily substance that prevents evaporation of the eye’s tear film, prevents tear spillage onto the cheek and makes the closed lids airtight

Question 8

describe lacrimal apparatus

Answer 8

1) excretory ducts of lacrimal gland
2) fluid pushed down and medially
3) plica semilunaris and lacrimal lake
4) inferior lacrimal papilla and punctum
5) lacrimal caruncle
6) lacrimal sac
7) nasolacrimal duct
8) inferior nasal meatus (where tear empty)

Question 9

lacrimal galnd is innervated by?

Answer 9

facial nerve

Question 10

what are the 3 layers of the eye?

Answer 10

1) fibrous layer (outer)
- - sclera -muscle atch
- - cornea -avascular, but innervated
2) vascular layer (middle)
- - choroid -red eye in pictures, really black
- - ciliary body -muscle for lens
- - iris -color, contains pupillary muscle
3) inner layer (inner)
- - retina -neurons

Question 11

corneal reflex afferent and efferent

Answer 11

cotton swab test
*afferent -nasociliary branch of the opthalmic branch of the trigeminal nerve (V1) sensing the stimulus on the cornea

*efferent - facial nerve (zygomatic branch) initiating the motor response of the orbicularis oculi

Question 12

define accommodation

Answer 12

the adjustment in the len’s shape to focus at various distance; under PARAsym (CN3) control

*ciliary muscles contract > zonular processes relax > lens thickens

Question 13

how do you see far away or near?

Answer 13

contraction= has parasym stimulation = release of ciliary muscle tension = spherical lens = close vision

relaxation= no nerve stimulation causing ciliary muscle to relax and tighten the zonular fibers = flattened lens = far vision

Question 14

pupillary light reflex afferent and efferent

Answer 14

afferent= optic nerve

efferent= oculomotor nerve (GVEs)
*Non-geniculate pathway- to midbrain nuclei then interneurons to BOTH edinger-Westphal n for CONSENSUAL

Question 15

medial vs lateral orbit walls

Answer 15

medial are parallel; like gaze
lateral are right angles
*axis of orbit diverge at 45 degrees

Question 16

out of all the extrinsic muscless, which is the only one attached to the eyelid?

Answer 16

levator palpebrae superioris

Question 17

movements of the pupil in the vertical, horizontal and AP Visual axis?

Answer 17

• verital= abduction or adduction
• horizontal= elevation or depression
• AP Axis= intorsion or extorsion

Question 18

oculomotor neve has 2 functional components so tow nuclei

Answer 18

1) GSE= motor= oculomotor nucleus

2) GVE= parasym= Edinger-Westphal nucleus

Question 19

CN 3 pathway?

Answer 19

fibers from both nuclei emerge from the midbrain medial to the cerebral peduncles and course anteriorly through the cavernous sinus to the orbit via superior orbital fissure

Question 20

CN 3 emerges through the common tendenous ring and then spltis into two divisions

Answer 20

1) superior division= levator palpebra superioris and superior rectus
2) inferior division= inferior rectus, inferior oblique, medial rectus, ciliary gangion AND CARRIES PARA

Question 21

define convergence

Answer 21

visual axes move closer together to keep approaching object focused on fovea centralis

Question 22

sphincter pupillae does what? para or sym?

Answer 22

• constricts the pupil in response to light AND to adjust field of vision/focus
• under para control -fibers carried by CN 3

Question 23

ciliary body of CN3 pathway

Answer 23

ciliary muscles attached to zonular fibers (attaching to lens)
*under Para contorl via GVE fibers carried by CN 3

Question 24

what are the 4 pathways for convergence/accommodation?

Answer 24

1) geniculate visualpathway is anything that goes through LGN
2) visual cortexes to CN nuclei for pupillary reflex
3) convergence- interneuron to oculomotor nuclei
4) accommodation (and pupillary constriction to increase visual acuity)- interneuron to EW nuclei

Question 25

accommodation (and pupillary constriction to increase visual acuity)- interneuron to EW nuclei with PRE and POSTsynaptic para?

Answer 25

pre= para neurons carry impulse to ciliary ganglion and synapse

post= carry to ciliary muscles and pupillary sphincter via short ciliary nerves

Question 26

what is the only CH that decasates before emerging?

Answer 26

CN 4 aka trochelar

Question 27

function of CN 4?

Answer 27

one extra-ocular muscle called superior oblique

*GSE

Question 28

CN 4 pathway

Answer 28

efferent fibers emerge from the DORSAL aspect of the midbrain, cross to contralateral side, and course anterolaterally through the cavernous sinuse to exit at superior oribtal fissure

Question 29

CN 4 does or doens’t pass thorugh common tendenous ring?

Answer 29

does NOT pass through ring but still passes thorugh superior orbital fissue

Question 30

common tendenous ring is origin for what muscles?

Answer 30

the 4 rectus muscles

*LPS and superior oblique are above it

Question 31

function of CN 6?

Answer 31

one extra-ocular muscle called lateral rectus

*GSE

Question 32

CN 6 pathway

Answer 32

efferent fibers emerge at the pontomedullary junction and travel through the cevernous sinus en route to the superior orbital fussure
*runs WITHIN tendinous ring