This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: None, Subject name: Ophthalmology
[{'content': 'Light reflex is carried through: March 2005 \nSelect and explain. \nA. Cranial nerve VI, B. Cranial nerve VII, C. Cranial nerve V, D. Cranial nerve II', 'role': 'user'}, {'content': 'Answer: D \nExplanation: Ans. D: Cranial nerve II The optic nerve is responsible for the afferent limb of the light reflex - it senses the incoming light. The oculomotor nerve is responsible for the efferent limb of the light reflex - it drives the muscles that constrict the pupil. Neuron 1: The light reflex pathway begins with retinal ganglion cells, which convey information from photoreceptors to the optic nerve ( the optic disc). The optic nerve connects to the pretectal nucleus of the upper midbrain, bypassing the lateral geniculate nucleus and the primary visual coex. Neuron 2: From the pretectal nucleus, axons connect to neurons in the Edinger-Westphal nucleus, whose axons run along both the left and right oculomotor nerves. Neuron 3: Oculomotor nerve axons synapse on ciliary ganglion neurons. Neuron 4: Neuron 4 innervates the constrictor muscle of the iris', 'role': 'assistant'}]