Sympathetic fibers can cause vasoconstriction of lacrimal gland blood vessels via which nerve?

• A. Vidian nerve
• B. Greater petrosal nerve
• C. Deep petrosal nerve
• D. Lacrimal nerve

Answer: (A)

Sympathetic regulation of lacrimal gland blood vessels travels with the nerve of the pterygoid canal. Postganglionic sympathetic fibers from the superior cervical ganglion ride along the internal carotid plexus into the deep petrosal nerve, then merge with the parasympathetic greater petrosal nerve to form the Vidian nerve (nerve of the pterygoid canal). Through the Vidian nerve these sympathetic fibers reach the pterygopalatine region and, after reaching the lacrimal gland area via branches that ultimately reach the lacrimal nerve, cause vasoconstriction of the gland’s blood vessels. The deeper point is that the other nerves mainly carry parasympathetic fibers for secretion (greater petrosal), a combination before forming the Vidian nerve (deep petrosal), or purely sensory/postganglionic pathways (lacrimal nerve), none of which collectively convey the sympathetic vasoconstrictor supply to lacrimal vessels.