Digastric muscle

The digastric muscle is a small muscle of the neck that extends from the front of the lower mandible (jaw bone) to the temporal bone of the skull in a curved form. It belongs to the suprahyoid muscle group.

The digastric muscle is made up of two muscular sections, called bellies, joined by rounded tendon. Each is supplied by a different cranial nerve. The posterior belly, the longer of the two, begins at the temporal bone of the skull and is supplied by the digastric branch of facial nerve. The anterior belly begins at the front lower section of the mandible and is attached to the hyoid bone by a fibrous loop. It is supplied by the trigeminal nerve (the fifth cranial nerve).

The digastric muscle divides the anterior triangle of the neck into three smaller triangles: The submandibular (digastric) triangle, the carotid triangle, and the suprahyoid (submental) triangle.

Action
When the digastric muscle contracts, it raises the hyoid bone. This motion is used during swallowing. This same action, when the hyoid bone is held in place by the infrahyoid muscles of the neck, results in the mouth opening.

Word origin
The name digastric comes from the Greek dis, meaning double, and gaster, Greek for stomach. It was named for its two sections that resemble the shape of the stomach.