Which muscle receives sympathetic innervation traveling with the superior division of CN III?

• A. Muller’s muscle
• B. Iris sphincter
• C. Ciliary muscle
• D. Superior Rectus

Answer: (A)

Sympathetic input to eyelid smooth muscle comes from the superior cervical ganglion and travels into the orbit via the internal carotid plexus. A portion of these fibers hitch a ride with branches of the oculomotor nerve to reach the eyelid. Muller's muscle (the superior tarsal muscle) is the smooth muscle in the eyelid that receives this sympathetic supply as it travels with the superior division of CN III. The iris sphincter and ciliary muscle are driven mainly by parasympathetic fibers that travel with CN III to the ciliary ganglion, not by sympathetic fibers. The superior rectus is a somatic motor muscle supplied by CN III, not by sympathetic fibers. So Muller's muscle is the one that receives sympathetic innervation traveling with the superior division of CN III.