[Hypoglossal nerve in its intralingual trajectory: anatomy and clinical implications]

There is little literature on the intralingual trajectory of the hypoglosal nerve. We performed an anatomical dissection on 6 cadavers and completed our study with histological examinations. The 12th cranial nerve enters the lower part of the tongue laterally, reaching the anterior border of the hypoglossal muscle where it follows the ascending lingual artery medially to terminate anteriorly to the lingual V. Its terminal branches spread out horizontally in each half of the tongue. There is a paramedial branch, found in all cases, which projects downwardly, posteriorly and medially at the basilingual portion of the genioglossal muscle. These anatomic findings indicate that basiglossectomy removing the entire base of the tongue can be performed without functional sequelae. A certain degree of somatotopy is also found with specific fibers reaching the protractor and retractor muscles. This nerve distribution supports attempts at selective electrical stimulation of the hypoglossal nerve with the aim of dilating the upper airways in patients with sleep apnea syndrome.