Orbit I/ II

Question 1

Layers of the eyelid

Answer 1

From external to internal:Skin, Subcutaneous connective tissue, Muscular layer, Submuscular layer, Tarsal Plate, Tarsal Glands & Palpebral conjunctiva

Question 2

Bones that make up the outer rim of eye

Answer 2

frontal, zygomatic, maxillary

Question 3

Palpebrae fissure

Answer 3

space between upper and lower eye lid

Question 4

lacrimal gland

Answer 4

located in the superolateral aspect of the orbit. It’s ducts drain into the superior palpebral fornix (located at the junction of the palpebral and orbital conjunctiva).

sensory from 5, motor from 7

Question 5

Lacrimal apparatus

Answer 5

Tears low from the superolaterally placed lacrimal gland, inferomedially to the medial cants of the eye where they drain:
puncta lacrimali- drain opening (2)
lacrimal canaliculus- duct (2)
lacrimal sac- collection of fluid
nasolacrimal duct: drainage to nasal sinus

Question 6

Nasociliary nerve branches (CN V1)

Answer 6

Communicating branch to the ciliary ganglion: runs through the ciliary ganglion (without synapsing), then reaches the eye by running through the short ciliary nerves.

Long ciliary nerves
Posterior ethmoidal nerve
Anterior ethmoidal nerve
Infratrochlear nerve

Question 7

Sympathetics to the eye

Answer 7

from the superior cervical ganglion via the internal carotid plexus and then the ophthalmic division of trigeminal (V1). These fibers pass through the ciliary ganglion and enter the eye via the short ciliary nerves. They innervate the dilator pupillae muscle (dilate pupil). Sympathetic fibers also reach the eye via long ciliary nerves

Question 8

Parasympathetics to the eye

Answer 8

from the Edinger-Westphal nucleus of the oculomotor nerve (CN III). They cause constriction of the pupil (sphincter pupillae m.) and allow the eye to focus on near objects (contraction of the ciliary muscle).

Question 9

Nerves of the orbit

Answer 9

Optic Nerve (II)
Oculomotor (III)
Trochlear (IV)
Trigeminal (V1)
Abducent (VI)
Sympathetics
Parasympathetics

Question 10

Ophthalmic veins

Answer 10

Venous drainage of the orbit is through the superior and inferior ophthalmic veins, which pass through the superior orbital fissure and enter the cavernous sinus

Question 11

Ophthalmic arteries

Answer 11

anterior/ posterior ethmoidal
supratrochlear
supraorbital
long/ short ciliary 
central retinal
lacrimal artery
ophthalmic artery

Question 12

Three layers of the eye

Answer 12

Sclera, Choroid, Retina

Question 13

Layers of the cornea

Answer 13

Epithelium, basement membrane, substantia propria, decenets membrane, endothelial layer

Question 14

Uveal layer

Answer 14

The middle layer, the uvea or uveal tract, is a highly vascular layer which is made up of three components: the choroid, ciliary body and the iris

Question 15

Ciliary muscle

Answer 15

parasympathetic only; the lens wants to be round, parasympathetic pulls tight, without innervation elasticity returns lens to round shape

Question 16

Ciliary process

Answer 16

production of aqueous humor

Question 17

Canal of Schlemm

Answer 17

reabsorption of aqueous humor through mesh surface at anterior chamber

Question 18

Glaucoma

Answer 18

Inability to drain excess fluid

1. angle open: angle is open for drainage but fluid cannot drain through mesh
2. angle closure: excess fluid raises lens which blocks angle stopping drainage from occurring

Question 19

Iris muscles

Answer 19

Constrictor pupillae: circular muscle, parasympathetic

Dilator pupillae- radial muscle, sympathetic

Question 20

Passage of light through eye

Answer 20

passes through:
axons and ganglion bodies, plexiform, inter nuclear layer, plexiform, outer nuclear layer, photoreceptor layer, epithelial layer

Question 21

Fovea

Answer 21

location for best visual acuity, cones only (no rods), no vessels, no cell bodies (pushed to side)

the further away you move from the fovea, the more rods are present

Question 22

Optic disc

Answer 22

axons form the optic nerve, no photoreceptors in this area (“blind spot”)

axons pierce sclera through lamina cribosa (holes in dura)