Orbit and Eyes Flashcards Preview

MD2- Neuroscience Block > Orbit and Eyes > Flashcards

Flashcards in Orbit and Eyes Deck (36):
1

What are the orbital margins?

supraorbital margin
-frontal bone

infraorbital margin
-zygomatic bone (laterally)
-maxilla (medially)

2

what are the bones of the roof of the orbit?

frontal bone, lesser wing of sphenoid

3

what are the bones of the floor of the orbit

maxilla, zygomatic, palatine

4

lateral wall orbit bones?

zygomatic, greater wing of sphenoid

5

medial wall of orbit bones?

lacrimal, ethmoid, maxilla, body of sphenoid

6

which orbital bones are most commonly broken

medial wall bones, lacrimal and orbital plate of ethmoid are paper thin

7

sclera?

white part of eyeball
5/6 of globe
maintains shape, offers resistance to internal & external forces
provides attachment of EOM

8

what contributes to sclera strength?

whirling patter of collagen deposition

9

what is the principal refracting component of the eye

cornea (it's transparent)

10

what are the 5 layers of the cornea

5 layers histologically including endothelium, descemets membrane, stroma (made of collagen), bowman's layer, and epithelum

11

why is cornea transparent

collagen fibrils are uniform in diameter and laid down in evenly spaced patttern, running parallel to eachother

12

anterior chamber angle?

junction b/w iris and cornea. aqueous humour drains out of here.-->maintains size and pressure of eyeball

13

what structures make up the anterior chamber angle?

corneal body, canal of schlemm, ciliary body, trabecular meshwork

14

describe passage of aqueous humour?

from ciliary body -->anterior chamber-->canal of schlemm-->out of the eye into venous system

15

uvea?

3 components: conjuctive, sclera, ciliary body
functions to improve retinal imaging by absorbing reflected light.
also its vessels perfuse the ciliary body and iris

16

where is aqueous humour produced?

ciliary body (ciliary epithelium)

17

function of ciliary body?

tethers lens (ciliary processes)
accomodation (ciliary muscle)
formation of aqueous humor (ciliary epithelium)

18

what is the purpose of aqeous humor?

provides intraocular pressure
maintaining health of lens and cornea

19

what is ocular accomodation?

Changes in contraction of the ciliary muscles alter the focal distance of the eye, causing nearer or farther images to come into focus on the retina.

ie. reflex to focusing on a near object and then a far away object.

depends on cranial nerve II and III.

20

which structures are involved in accomodation?

ciliary muscle
zonules that attach to the lens

21

what are zonules

ligaments that attach between ciliary processes and lens. are involved in accomodation.

22

ciliary muscle receives Parasympathetic or Sympathetic innervation?

Parasympathetic!
non-voluntary (smooth muscle).

23

what happens to ciliary muscle when looking at far away things?

ciliary muscle relaxes-->diameter of lens increases
-->zonules constrict

24

what happens to ciliary muscle when looking at far away things?

ciliary muscle constricts--->diameter of lens decreases
-->zonules relax

25

presbyopia?

loss of ability to perform accommodation with age.
due to reduction in flexibility of lens capsule and zonules.

26

iris? muscles involved?

aperture of the eye.
1. sphincter pupillae: constricts pupil, innervated by PS.
2. dilator pupillae: dilates pupil, innervated by sympathetic NS.

27

choroid

3 layers of blood vessels
-choriocapillaris is most important, sits just below retina

supplies nutrients to the retina.

28

retina (5 components)

optic nerve/disc
fovea/foveola
macular
posterior pole
orro serrata

29

fovea?

high visual acuity
avascular (gets nutrients from choroid)
no cones, all rods

foveal pits permit direct access to photoreceptors.

30

what forms optic nerve

axons of ganglion cells as they exit the retina to pass visual information to higher cortical areas.

nerve is encased in a dural sheath. within that, 2/3 of the sclera forms a sheath around the nerve.
1/3 of sclera goes across the optic nerve, "lamina cribrosa".

31

lamina cribrosa?

band of dense CT.
provides extra strength where optic nerve enters the eye.

if pressure in the eye builds up , the LC bulks up and exerts pressure, causing loss of vision-->glaucoma

32

vascular supply to the orbit?

ciliary arteries,

tributaries of ophthalmic artery,

central retinal artery

33

what are the 3 ciliary arteries?

long posterior ciliary artery (pierce choroid and fans out to reach anterior portion),

short posterior ciliary artery (closest to optic nerve),

and anterior ciliary artery (runs along the eyeball to the anterior portion where it supplies the cornea).

34

blood supply to retina?

dual supply.
central retinal artery supplies the inner retina.
posterior retinal artery supplies the outer retina (photoreceptors).

35

muscles of the eyelid?

orbicularis oculi (sphincter muscle, closure, facial nerve, VII)
and levator palpebrae superiosis (striated muscle, opens, oculomotor III)

36

lacrimal apparatus

lacrimal ducts and gland
nasolacrimal duct and sac