The geniohyoid lies superior to the mylohyoid, connecting the mandible to the hyoid. It is one of the suprahyoid muscles elevating the hyoid and floor of mouth during swallowing. Its C1 innervation via the hypoglossal nerve is clinically important — hypoglossal nerve lesions may paradoxically produce geniohyoid weakness despite it not being a tongue muscle.
| Origin | Inferior mental spine (genial tubercle) on the inner surface of the mandibular symphysis |
|---|---|
| Insertion | Body of the hyoid bone |
| Nerve Supply | C1 fibres via the hypoglossal nerve (XII) |
| Blood Supply | Submental artery |
| Actions | Elevates and protracts the hyoid during swallowing; Depresses the mandible when the hyoid is fixed |
|---|
The geniohyoid is a target in tongue base advancement procedures for sleep apnoea — geniohyoid myotomy and advancement (with genioglossus advancement) moves the tongue base forward to open the hypopharyngeal airway. The genial tubercle osteotomy for genioglossus advancement is performed immediately around the geniohyoid and genioglossus origins.
The geniohyoid is not palpable separately from the sublingual floor — assessed alongside the mylohyoid.
Geniohyoid and suprahyoid weakness from C1 or hypoglossal lesions contributing to hyoid elevation failure and swallowing dysfunction.
