Eye Anatomy and Physiology

Question 1

What are the 3 layers of the eye, going from outside to inside?

Answer 1

The sclera, choroid and retina.

Question 2

What is important about the sclera?

Answer 2

Several occular muscles attach here.

Question 3

What’s in the choroid?

Answer 3

Branches of the retianl arteries as well as nerve fibers other than the optic nerve. Autonomic nerves that innervate smooth muscles in the anterior of the eyeball, sensory nerve fibers that innervate the cornea (by the opthalmic region of cranial nerve 5, V1).

Question 4

What can be found in the retina?

Answer 4

Nerves of the optic nerve will come out of the retina and converge at the optic disc.

Question 5

What is the Fovea?

Answer 5

Area in the retina with the highest concentration of cones, to achieve the highest visual acuity and color.

Question 6

What is the posterior chamber and what does it contain?

Answer 6

Area between the lens and the posterior chamber of the iris, this is where ciliary bodies exist and produce aqueous humor.

Question 7

What is the anterior chamber and what does it contain?

Answer 7

It is the area between the iris and the cornea, and it contains the “Canal of Schlemm” which is involved with draining the aqueous humor.

Question 8

Which 2 muscles in the anterior eye have parasympathetic innervation and by what? Sympathetic innvervation and by what?

Answer 8

Ciliary muscles and constrictor pupillae have parasympathetics from CN3, dilator pupillae from sympathetics (T1 to superior cervical ganglion).

Question 9

Describe the pathway of neural stimulus from the eye to the brain.

Answer 9

Light stimulates ganglion retinal cells, impulse travels up CN2, which projects bilaterally to the pretectal nuclei in the midbrain. This nucleus then projects bilaterally to the pre-ganglionic parasympathic neurons found in Edinger-Westphal nuclei (midbrain). This projects into the ciliary ganglion and postganglionic parasympathetics –> goes to innervate the pulillary sphincter muscles, causing pupillary constriction.

Question 10

Where does the optic nerve project to in the brain? Where does it go from there?

Answer 10

Pretectal nuclei in midbrain. This projects onto the Edinger-Westphal nuclei, which projects to the ciliary ganglion and the postganglion parasympathetics to the muscle.

Question 11

What kind of receptors do the parasympathetics of the eye use?

Answer 11

M3 muscuranic receptors.