Mylohyoid muscle

The mylohyoid muscle is a muscle running from the mandible to the hyoid bone, forming the floor of the oral cavity.

Structure
The mylohyoid muscle is flat and triangular, and is situated immediately above the anterior belly of the digastric muscle. It forms, with its fellow of the opposite side, a muscular floor for the cavity of the mouth.

It arises from the whole length of the mylohyoid line of the mandible, extending from the symphysis in front to the last molar tooth behind. The posterior fibers pass medialward and slightly downward, to be inserted into the body of the hyoid bone. It thus belongs to the suprahyoid muscles.

The middle and anterior fibers are inserted into a median fibrous raphé extending from the symphysis menti to the hyoid bone, where they joint at an angle with the fibers of the opposite muscle. This median raphé is sometimes absent; the fibers of the two muscles are then continuous.

Innervation
The mylohyoid muscle, along with the anterior belly of the digastric muscle, is innervated by the mylohyoid nerve, a nerve that ultimately arises from the mandibular division of the trigeminal nerve.

Variations
It may be united to or replaced by the anterior belly of the digastric muscle; accessory slips to other hyoid muscles are frequent.