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Charita Banthiyaover 1 year ago

What is the neural pathway responsible for the pupillary light reaction?

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over 1 year ago

Normal pupillary light reflex is the bilateral constriction of pupil when light is shown in one light. The other pupil constricts as a consensual reflex. Light travels through cornea, pupil, and lens and falls on retina. Stimulus by photoreceptors is relayed to optic disc and optic nerve (CN II) which carries impulses through optic chiasma. Where fibers diverge to left and right (nasal fibers cross and temporal on the ipsilateral side). Optic tract joins superior colliculus, pretectal area to midbrain (Edinger westphal nucleus). Efferent fibers travel in ovulomotar nerves and synapse on ciliary ganglion which then send nerves to sphincters leads to pupillary constriction. The crossing fibers are the reason for consensual or indirect reflex of pupil to light.

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