Geniohyoid muscle

The geniohyoid muscle is a muscle in the neck that connects the mandible (jaw bone) to the hyoid bone in the throat.

Origin
The geniohyoid originates from the mandible (jaw bone) at the the symphysis menti on the inferior mental spine on the posterior (internal) surface.

Insertion
The geniohyoid inserts on the hyoid bone, at the superior border of the body.

Innervation
The geniohyoid is innervated by the hypoglossal nerve (CN XII), however, the fibers that innervate it originate from C1 and are carried by the hypoglossal nerve.

Blood supply
There are no major arteries that supply blood flow into the geniohyoid - instead it relies on smaller blood vessels.

Action
When it is contracted, the muscle raises the hyoid bone which consequently raises the larynx. This action assists in performing a swallowing motion, raising the tongue for speech, and also depressing the mandible which can function in either eating or speaking.

Variations
The muscle itself can vary person to person, sometimes appearing twice, and sometimes portions may be missing on one side of the hyoid bone.

Word origin
The word comes from genio (chin), referring to its origin on the mandible, and hyoid, from its insertion on the hyoid bone.