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USMLE Step 1 Bits & Pieces High yield short focused points, monographs, charts, illustrations, tables, and other stuff related to the USMLE Step 1 Exam.

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Old 08-02-2011
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Default the eye

Here are bits that i picked up form the visual system, in terms of the innervation to different pathways:

1. Accomodation: via the ciliary muscle --> parasympathetic ( M3 muscarinic, when brought near), Sympathetic (b2 , when you want to accomodate far ( hence relax the muscle)

2. Dilatation of the pupil : Iris dilator muscle via Sympathetic alpha 1 ( v1 fibers(long ciliary nerve) --> alpha 1 receptor
* affected in Horner's Syndrome *

3. Pupillary light reflex: sphincter of the iris --> via Parasympathetic pathways ( through CN 3, short ciliary nerves).

If anyone of you find mistakes in the above please let me know asap. thanks .
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The above post was thanked by:
dr_lizard (09-03-2011), drgabroomunda (11-30-2011), NAZIAMK (08-10-2011), riya10 (08-04-2011)


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