digastric

Digastric refers to a paired muscle of the neck, one of the suprahyoid muscles. It consists of two muscle bellies—the anterior and the posterior—joined by an intermediate tendon that loops through a fibrous sling attached to the body of the hyoid bone. The digastric muscle helps position the hyoid during swallowing and speech and can assist in opening the mouth when the hyoid is fixed.

The anterior belly originates from the digastric fossa on the inner surface of the mandible near the chin and inserts into the intermediate tendon. The posterior belly arises from the mastoid notch on the temporal bone and also inserts into the same tendon. The tendon passes through a fibrous loop anchored to the hyoid, coordinating the two bellies’ actions.

Innervation differs between the two bellies: the anterior belly is supplied by the mylohyoid nerve, a branch of the mandibular division of the trigeminal nerve (V3). The posterior belly is innervated by the facial nerve (cranial nerve VII) via a digastric branch.

Blood supply also comes from distinct sources. The anterior belly receives branches of the facial artery, including the submental artery. The posterior belly is supplied by branches from the posterior auricular and occipital arteries.

Functionally, the digastric elevates the hyoid bone during swallowing and speaking. When the hyoid is fixed, contraction of the digastric can help depress the mandible, aiding in jaw opening. The term digastric derives from Latin roots meaning “two-bellied.” Variations exist, with occasional accessory slips or a single-bellied form.