The Pupillary Light Reflex | Structure & Clinical Interpretation

The video tutorial explains the pupillary light reflex (PLR), involving cranial nerves II (optic) and III (oculomotor). It covers the direct and consensual reflexes, demonstrating how light in one eye affects pupil constriction in the same or opposite eye. The tutorial includes a test demonstration and discusses diagnosing lesions in the reflex pathway, highlighting the effects of lesions on optic and oculomotor nerves.

Which cranial nerves are involved in the pupillary light reflex?

• Cranial nerves I and II

• Cranial nerves II and III

• Cranial nerves III and IV

• Cranial nerves IV and V

What happens during a direct reflex?

• Light in one eye causes constriction in the opposite eye

• Both pupils constrict when light is shone in one eye

• Neither pupil constricts when light is shone in one eye

• Light in one eye causes constriction in the same eye

How is the consensual reflex named?

• By the eye that receives the light

• By the eye that constricts

• By the intensity of light

• By the direction of light

What is the purpose of the swing flashlight test?

• To test the visual acuity

• To test both direct and consensual reflexes

• To test the consensual reflex only

• To test the direct reflex only

What is the role of the optic nerve in the pupillary light reflex?

• It is not involved in the reflex

• It controls the eyelid movement

• It is the sensory limb of the reflex

• It is the motor limb of the reflex

What happens if the left optic nerve is lesioned?

• Right direct reflex is lost

• Right consensual reflex is intact

• Left direct reflex is lost

• Left direct reflex is intact

In a left oculomotor nerve lesion, which reflexes are lost?

• Right direct and left consensual

• Left direct and right consensual

• Right direct and right consensual

• Left direct and left consensual

How can you differentiate between an optic nerve lesion and an oculomotor nerve lesion?

• By checking the visual acuity

• By observing which side loses the consensual reflex

• By measuring pupil size

• By testing the corneal reflex

What is the effect of a right optic nerve lesion on reflexes?

• Loss of left direct and left consensual reflexes

• Loss of right direct and left consensual reflexes

• Loss of left direct and right consensual reflexes

• Loss of right direct and right consensual reflexes

What is the primary function of the oculomotor nerve in the pupillary light reflex?

• To transmit sensory information

• To control pupil constriction

• To detect light intensity

• To regulate tear production