Lingual nerve

The lingual nerve is a branch of the mandibular nerve (CN V3), itself a branch of the trigeminal nerve. The lingual nerve supplies sensory innervation to the mucous membrane of the anterior two-thirds of the tongue. It also carries nerve fibers that do not originate from the trigeminal nerve, including taste sensation to the anterior part of the tongue as well as parasympathetic and sympathetic fibers. The submandibular ganglion is suspended by two nerve filaments from the lingual nerve.

The lingual nerve lies at first beneath the lateral pterygoid muscle, medial to and in front of the inferior alveolar nerve, and is occasionally joined to this nerve by a branch which may cross the internal maxillary artery.

The chorda tympani (a branch the facial nerve, CN VII) joins it at an acute angle here, carrying taste fibers from the anterior two thirds of the tongue and parasympathetic fibers to the submandibular ganglion.

The nerve then passes between the medial pterygoid muscle and the ramus of the mandible, and crosses obliquely to the side of the tongue over the Constrictor pharyngis superior and Styloglossus, and then between the Hyoglossus and deep part of the submandibular gland; it finally runs across the duct of the submandibular gland, and along the tongue to its tip, lying immediately beneath the mucous membrane.

Mnemonic
Students of anatomy are aided in learning this material through the following sextet:
 * The lingual nerve
 * Describes a curve
 * Across the hyoglossus
 * Said Wharton's duct
 * "Well I'll be fucked--
 * That bastard's double-crossed us."