Deep petrosal nerve

The deep petrosal nerve is a post-ganglionic branch of the internal carotid (nervous) plexus that enters the cranial cavity through the carotid canal, then passes perpendicular to the carotid canal in the cartilaginous substance which fills the foramen lacerum to unite with the greater petrosal nerve to form the nerve of pterygoid canal (Vidian nerve).

Anatomy

The path of the fibers from the spine to the lacrimal gland is as follows: intermediate grey column → white rami communicantes → superior cervical ganglion → gray rami communicantes → internal carotid plexus → deep petrosal nerve → nerve of pterygoid canal → pterygopalatine ganglion → zygomatic nerve → zygomaticotemporal nerve → lacrimal nerve.

Origin

The cell bodies of pre-ganglionic sympathetic axons that subsequently give synapse with neurons of the deep petrosal nerve reside in the intermediate grey column of the spinal cord at around the spinal level of T1. The pre-ganglionic axons ascend in the sympathetic trunk to synapse at the superior cervical ganglion where the cell bodies of the fibres of the deep petrosal nerve are situated. The post-ganglionic fibres do not synapse again and ultimately innervate their target tissues directly.

Function

The deep petrosal nerve carries post-ganglionic sympathetic axons which are ultimately distributed to the blood vessels, and exocrine glands of the lacrimal gland, nasal cavity, and oral cavity.