This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: Nervous System, Subject name: Physiology
Pupillary reflex is controled by which nucleus- 
Select and explain. 
A. Edinger westphal nucleus, B. Nucleus tractus solitarus, C. Nucleus ambiguus, D. Dorsal vagus nucleus
A: Edinger westphal nucleus
Answer: A: Edinger westphal nucleus 
Explanation: Ans. is 'a' i.e., Edinger westphal nucleusPupillary light reflex (Light reflex)* Pupillary light reflex refers to constriction of pupil in response to light. When a sudden light is thrown into the eye, the pupil of that eye constricts (direct light reflex). The pupil of other eye also constricts (Consensual or indirect light reflex). The pathway for pupillary reflex involve (sequentialy): -i) Afferent: - Retina - Optic nerve - Optic chiasma - Optic tract - Pretectal nucleus - Internuncial neurons - EWN (Edinger westphal nucleus).ii) Efferent: - Edinger westphal nucleus - Occulomotor (3rd) nerve - Ciliary ganglion Short ciliary nerve - Sphinctor pupillae.* Some fibres decussate at optic chiasma and go to contralateral side which is responsible for consensual or indirect light reflex. From retina upto the Pretectal nucleus is afferent pathway and from EWN of third nerve to sphincter pupillae is efferent pathway.