Question

the pupillary reflex is

a. monosynaptic.
b. polysynaptic.

Explanation:

Define the pupillary reflex

The pupillary light reflex is an autonomic reflex that controls the diameter of the pupil in response to the intensity of light that falls on the retinal ganglion cells of the retina in the back of the eye, thereby assisting in adaptation of vision to various levels of lightness/darkness.

Analyze the neural pathway

Using the Polysynaptic Reflex Arc knowledge point

• The sensory signal travels from the retina along the optic nerve (CN II) to the pretectal nucleus in the midbrain.
• Interneurons project from the pretectal nucleus to the Edinger-Westphal nuclei on both sides of the brain.
• Parasympathetic preganglionic fibers travel via the oculomotor nerve (CN III) to the ciliary ganglion.
• Postganglionic fibers excite the pupillary sphincter muscle.
• Because this pathway involves multiple synapses (including interneurons in the pretectal area), it is classified as polysynaptic.

Answer:

• a. monosynaptic.
• b. polysynaptic. (Correct answer)