genioglossus

The genioglossus is a fan-shaped extrinsic muscle of the tongue. It originates from the superior mental spine on the inner surface of the mandible and fans posteriorly to insert into the dorsum of the tongue, with some fibers extending into the body of the tongue and others reaching toward the hyoid bone. It is one of the primary muscles involved in moving the tongue and shaping its position within the mouth.

Its most important action is protrusion of the tongue. Bilateral contraction of the genioglossus mainly protrudes the tongue, while the posterior fibers can help depress the tongue’s center and aid in drawing the tongue back toward the floor of the mouth. Unilateral contraction can cause the tongue to deviate toward the side of the muscle that is pulled, which is relevant in neurological assessment after cranial nerve injury.

The muscle is innervated by the hypoglossal nerve (cranial nerve XII). Its arterial supply comes from branches of the lingual artery, with the deep lingual branches contributing to the vascularization of the muscle. Clinically, the genioglossus is notable for its role in airway maintenance and tongue posture, and weakness or asymmetry can affect tongue movement and oral function, as seen in certain neurologic conditions and sleep-disordered breathing.