Neurologic Exam-Adult | Cranial Nerve Exam | Normal | Cranial Nerves 2 & 3- Pupillary Light Reflex

Cranial Nerve Exam - Normal 05 - Cranial Nerves 2 & 3- Pupillary Light Reflex: The afferent or sensory limb of the pupillary light reflex is CN2 while the efferent or motor limb is the parasympathetics of CN3. Shine a flashlight into each eye noting the direct as well as the consensual constriction of the pupils. The swinging flashlight test is used to test for a relative afferent pupillary defect or a Marcus Gunn pupil. Swinging the flashlight back and forth between the two eyes identifies if one pupil has less light perception than the other. Shine the flashlight at one eye noting the size of both pupils. Then swing the flashlight to the other eye. If both pupils now dilate then that eye has perceived less light stimulus (a defect in the sensory or afferent pathway) than the opposite eye.