geniohyoid

The geniohyoid is a slender, paired muscle of the neck that belongs to the suprahyoid group. It runs from the mandible to the hyoid bone, forming part of the midline floor of the mouth region.

Origin and insertion: It originates from the inferior mental spine (genial tubercle) on the inner surface of the mandible near the symphysis menti and inserts into the body of the hyoid bone, along its superior aspect. The muscle lies superior to the mylohyoid and medial to the other suprahyoid muscles.

Innervation and blood supply: The geniohyoid is innervated by nerve fibers from the first cervical spinal nerve (C1) carried by the hypoglossal nerve (CN XII). Its arterial supply comes from branches of the lingual and facial arteries, with additional small contributions from nearby vessels.

Function: The primary action is to elevate and pull the hyoid bone anterosuperiorly during swallowing, aiding the opening of the pharynx and elevation of the larynx. It also helps shorten the floor of the mouth. When the mandible is fixed, it can assist in depressing the mandible.

Clinical significance and variation: The geniohyoid can vary in size and form, and rare congenital variations or atrophy may affect swallowing mechanics. It serves as an anatomic landmark in neck and floor-of-mouth surgical procedures and in the interpretation of imaging of the anterior neck. Injury to nearby C1 fibers through hypoglossal nerve pathways can impact its function.