Deep petrosal nerve

The deep petrosal nerve is a post-ganglionic branch of the (sympathetic) internal carotid (nervous) plexus (which is in turn derived from the superior cervical ganglion, a part of the cervical sympathetic trunk) that enters the cranial cavity through the carotid canal. It then passes perpendicular to the carotid canal in the cartilaginous substance which fills the foramen lacerum to unite with the (parasympathetic) greater petrosal nerve (a branch of the facial nerve (CV VII)) to form the nerve of pterygoid canal (Vidian nerve). Through this connection it conveys sympathetic fibers through the pterygopalatine ganglion without synapsing. These post-ganglionic fibers are distributed to the nasal cavity, palate, and lacrimal gland via branches of the maxillary nerve. The deep petrosal nerve contributes to autonomic regulation of glandular secretion and vascular tone in regions of the nasal cavity and palate and is relevant in surgical approaches involving the pterygopalatine fossa.