The embryologic period occurs during the first eight weeks following fertilization. The infrahyoid muscles are the antagonistic muscles to the digastric. The contraction of the posterior digastric muscle participates in the extension of the head. Furthermore, the digastrics work to depress the mandible for jaw opening, chewing, and speech. The digastric muscle functions during swallowing, chewing, and speech. The anterior belly of the digastric is one of the three suprahyoid muscles which stabilizes the hyoid during swallowing, an action critical in protecting the airway while eating. The posterior belly of the digastric also serves as a boundary for the carotid triangle, which is where the facial artery branches from the external carotid. The submental triangle is bordered laterally by the anterior belly and houses lymph nodes that drain the floor of the mouth and part of the tongue. The submandibular triangle, bordered by the anterior and posterior bellies of the digastric and the inferior border of the mandible, houses the submandibular gland, anterior facial vein, submental artery, mylohyoid nerve and vessels, and the external carotid.
The anterior belly of the digastric divides the submental and submandibular triangles of the neck. The tendon runs through a fibrous loop attached to the hyoid bone at the body and greater cornu. The intermediate tendon typically courses through the stylohyoid muscle, but variations are found lying medial or lateral to it. The posterior belly attaches to the temporal bone at the mastoid process and slopes to meet the intermediate tendon. The anterior belly of the digastric attaches near the midline of the base of the mandible on the digastric fossa and runs toward the hyoid. The two bellies connect by an intermediate tendon. The neck contains a pair of digastric muscles, each of which subdivides into an anterior and posterior belly.