Pupillary Light Reflex

Question 1

what is the pupillary light reflex

Answer 1

Bilateral reflex constricts the pupils in response to light
- entirely mediated by the Para sympa
- used to assess integrity of optic nerve, oculomotor nerve, and midbrain

Question 2

how is constriction accomplished

Answer 2

parasympathetic fibers from the ciliary ganglion constrict the pupil by contracting the pupillary constrictor muscle

Question 3

what is the pathway for the pupillary light reflex

Answer 3

1) retinal ganglion cell (via optic nerve, optic tract, optic chiasm)
2) Pretectal area (midbrain) (via bilateral projection)
3) Endinger-westphal nucleus (via axons of preganglionic cells)
4) ciliary ganglion (via axons post ganglionic cells)
5) Pupillary constrictor muscle