This site is intended for healthcare professionals

account_circleSign in
Go to /sign-in page

You can view 5 more pages before signing in

Anatomy of the pupillary reflexes

Last reviewed dd mmm yyyy. Last edited dd mmm yyyy

Authoring team

The size of the pupils depends on the balance of sympathetic and parasympathetic activity supplying the iris:

  • sympathetic activity tends to dilate the pupil
  • parasympathetic activity tends to constrict the pupil

The pathway of the pupillary light reflex consists of:

  • retinal receptor cells
  • bipolar cells
  • ganglion cells
  • optic nerve and tract
  • pretectal nucleus of the high midbrain
  • Edinger-Westphal nucleus
  • efferent two neurone pathway via the oculomotor nerve
  • constrictor muscle of the iris

It should be noted that the lateral geniculate nucleus of the thalamus and the cerebral cortex are not involved in the pupillary reflexes. Hence a patient who is cortically blind will have intact light reflexes.

Related pages

Create an account to add page annotations

Create a free account

Add information to this page that would be handy to have on hand during a consultation, such as a web address or phone number. This information will always be displayed when you visit this page