What is the consensual response?

Both pupils constrict when one eye is lit

Which nervous system dilates the pupil?

The parasympathetic nervous system

What does the swinging flashlight test detect?

A problem in one optic nerve or retina

Pupillary Light Reflex Quiz: How Eyes Adjust to Brightness

Your pupils adjust within a fraction of a second when you step from a dark room into sunlight, and this pupillary light reflex quiz explains the nerves behind it. Play 10 interactive questions on constriction and dilation, the optic and oculomotor nerves, the consensual response, the Edinger-Westphal nucleus, iris muscles, normal pupil sizes and the swinging flashlight test.

Start Pupillary Light Reflex Quiz

🎯 Daily Trivia Challenge • 🧠 10 Questions • ⏱️ 150 Seconds

Question 1 / 10 Time: 150s

Response
What happens to the pupil in bright light?
Term
What is the medical term for pupil constriction?
Afferent
Which nerve carries the light signal to the brain?
Efferent
Which nerve carries the command to constrict?
Both
What is the consensual response?
Nucleus
Which brainstem nucleus sends the parasympathetic signal?
Muscle
Which muscle shrinks the pupil?
Dilate
Which nervous system dilates the pupil?
Test
What does the swinging flashlight test detect?
Doctors
Why do emergency doctors check pupil reflexes?

Explanations: answer key for all 10 questions

Q1: What happens to the pupil in bright light?
Answer: It constricts
Less light enters the eye.
Q2: What is the medical term for pupil constriction?
Answer: Miosis
Mydriasis means dilation.
Q3: Which nerve carries the light signal to the brain?
Answer: The optic nerve
It is cranial nerve II.
Q4: Which nerve carries the command to constrict?
Answer: The oculomotor nerve
It is cranial nerve III.
Q5: What is the consensual response?
Answer: Both pupils constrict when one eye is lit
Signals cross in the brainstem.
Q6: Which brainstem nucleus sends the parasympathetic signal?
Answer: The Edinger-Westphal nucleus
It lies in the midbrain.
Q7: Which muscle shrinks the pupil?
Answer: The sphincter pupillae
It rings the pupil.
Q8: Which nervous system dilates the pupil?
Answer: The sympathetic nervous system
Fear and darkness widen pupils.
Q9: What does the swinging flashlight test detect?
Answer: A problem in one optic nerve or retina
It reveals a relative afferent pupillary defect.
Q10: Why do emergency doctors check pupil reflexes?
Answer: To assess brain and brainstem function
Unequal or fixed pupils can signal danger.

Pupillary Light Reflex Quiz – How Eyes Adjust to Brightness

The pupillary light reflex makes the pupils constrict in bright light and widen in dim light. Light detected by the retina travels along the optic nerve to the midbrain, where signals pass to the Edinger-Westphal nucleus.

Parasympathetic fibers then travel along the oculomotor nerve to the sphincter pupillae muscle, which shrinks the pupil, a response called miosis. Because signals cross in the brainstem, lighting one eye makes both pupils constrict, the consensual response. Sympathetic nerves dilate the pupil.

Doctors check the reflex with a penlight to assess brain and brainstem function. The swinging flashlight test can reveal a relative afferent pupillary defect, a sign of optic nerve or retinal damage.

What This Quiz Teaches

Students and health fans will enjoy these questions.

How the reflex works
Which nerves are involved
What the consensual response is
Which muscles act
How doctors use it

Did You Know?

Pupils typically range from about 2 to 8 mm.
Some eye drops dilate pupils for exams.
Special retinal cells with melanopsin help drive the reflex.
Pupils also narrow when focusing on near objects.
Certain drugs can make pupils pinpoint.