Re: Orbit and Globe - Part II

Comments:
: : : Orbit and Globe - Learning Objectives and Review Questions : : : True/False : : : True/False - October 08, 2011 - Dr. Quillen : : : 1. The lens provides 66% of the refractive index of the globe and the cornea provides 33%. : : F - cornea provides ~2/3, : Agree : : : 2. The orbital septum separates the region of the face from the orbit. : : T? - extends around around the orbital rim and separates eyelid tissues from the orbit : Agree : : : 3. The upper medial superior conjunctival fornix receives tears from the ducts of the lacrimal gland. : : F - lateral superior conjunctival fornix? : Agree : : : 4. The eyelids play a critical role in protecting the eye. : : T : Agree : : : 5. The meibomian glands secrete tears in response to irritation and the lacrimal gland secretes tears to assure lubrication. : : F - lacrimal gland secretes tears in response to irritation : Agree : : : 6. The meibomian glands are also known as the tarsal glands. : : T : Agree : : : 7. The lacrimal gland is mostly involved with reflexive tearing and the accessory lacrimal glands are primarily responsible for tear film. : : T : Agree : : : 8. The vascular tone of the conjunctiva, if low, leads to conjunctival injection (red eye). : : T? - since this would be synonymous w/ blood vessel dilation? : Agree, poorly worded on my part. Vascular tone is determined by sympathetics. Check Horner's syndrome. : : : 9. Loss of sympathetic tone to the orbit is a cause of conjunctival injection. : : T? - See above? : Agree : : : 10. Conjunctival injection is a symptom of Horner's syndrome. : : T : Agree : : : 11. Total refraction of the eye is 1/3 by cornea and 2/3 by lens. : : F - flip the proportions. Isn't this the same as Q1? : Agree. Dr. Quillen repeated this about 5 times. I thought I would emphasize it with two questions. : : : 12. Flattening the cornea changes the refractive properties of the eye. : : T - yay Lasik! : Agree : : : 13. The corneal arterial plexus is derived from the lacrimal artery. : : T? - is this refers to the anastemosing conjunctival arteries around the rim of the cornea. There's also an annular nerve plexus that innervates the cornea itself, derived from the ciliary nerves. : False. I made it up. The cornea is avascular as I understand it. Hence, the clarity. : : : 14. End arteries feed the cornea and blockage of these arteries leads to corneal necrosis. : : T? - I'd assume blockage of the blood supply could lead to necrosis, but the more common mechanisms for corneal ulceration are bacterial : False. The cornea, as I understand it, is supported by the aqueous humor. No blood supply. At least, not macroscopic. : : : 15. The pain of corneal abrasions is minor because the neural supply to the cornea is slight. : : AHAHAHAHAHAHA...I wish. False. : Agree. Fell asleep with the contacts eh? : : : 16. The primary sensory cell bodies that mediate corneal pain are located in the geniculate ganglion. : : F? : Agree. The trigeminal ganglion.

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