Corpus: Lesser petrosal nerve

The lesser petrosal nerve, or LPN for short, is a continuation of the tympanic nerve, carrying preganglionic parasympathetic fibers from the inferior salivatory nucleus to the otic ganglion. It emerges from the tympanic plexus and provides the secretory innervation of the parotid gland.

The lesser petrosal nerve enters the middle cranial fossa through the hiatus for the lesser petrosal nerve and then runs forward in the groove for the lesser petrosal nerve on the anterior surface of the petrous part of the temporal bone. It exits the cranial cavity through the sphenopetrosal fissure, a lateral extension of the foramen lacerum. Occasionally, it may also pass through the foramen ovale. Inside the skull, it gives off a communicating branch to the geniculate ganglion.

Immediately below the foramen, the nerve connects to the otic ganglion, where its fibers synapse with the second neuron. Through a communicating branch, the postganglionic fibers reach the auriculotemporal nerve, which carries them to the parotid gland.

Together with the tympanic nerve, the lesser petrosal nerve forms part of the Jacobson's anastomosis.