Question

The sphincter pupillae gets parasympathetic innervation from?

a) CN III (oculomotor nerve)

b) CN V1 (ophthalmic division)

c) CN VII (facial nerve)

d) CN VI (abducens nerve)

Answer 1

The sphincter pupillae gets parasympathetic innervation from the oculomotor nerve (CN III), originating from the Edinger-Westphal nucleus.

Step-by-step explanation:

The sphincter pupillae gets parasympathetic innervation from the oculomotor nerve (cranial nerve III), according to the options provided. The Edinger-Westphal nucleus, part of the oculomotor complex in the midbrain, gives rise to preganglionic parasympathetic fibers. These fibers travel with the oculomotor nerve to the ciliary ganglion located in the posterior orbit. Postganglionic parasympathetic fibers then project from this ganglion to the sphincter pupillae muscle in the iris to control pupil size. Consequently, the correct answer is a) CN III (oculomotor nerve).