Digastric muscle

Digastric muscle
Muscles of the neck. Lateral view.
Front view of neck.
Details
Origin	anterior belly - digastric fossa (mandible); posterior belly - mastoid process of temporal bone
Insertion	Intermediate tendon (hyoid bone)
Artery	anterior belly - Submental branch of facial artery; posterior belly - occipital artery
Nerve	anterior belly - mandibular division (V3) of the trigeminal (CN V) via the mylohyoid nerve; posterior belly - facial nerve (CN VII)
Actions	Opens the jaw when the masseter and the temporalis are relaxed.
Identifiers
Latin	musculus digastricus
Dorlands /Elsevier	m_22/12548801
TA	A04.2.03.002
FMA	46291
Anatomical terms of muscle []

The digastric muscle (also digastricus) (named digastric as it has two 'bellies') is a small muscle located under the jaw. The term "digastric muscle" refers to this specific muscle. However, other muscles that have two separate muscle bellies include the ligament of Treitz, omohyoid, occipitofrontalis.

It lies below the body of the mandible, and extends, in a curved form, from the mastoid process to the symphysis menti. It belongs to the suprahyoid muscles group.

A broad aponeurotic layer is given off from the tendon of the digastricus on either side, to be attached to the body and greater cornu of the hyoid bone; this is termed the suprahyoid aponeurosis.

The digastricus (digastric muscle) consists of two muscular bellies united by an intermediate rounded tendon.

The two bellies of the digastric muscle have different embryological origins, and are supplied by different cranial nerves.

Each person has a right and left digastric muscle. In most anatomical discussions, the singular is used to refer to a muscle, even when each person actually has two of that muscle -- one on the right side, and another on the left. For example, we speak of the deltoid, even though there is one deltoid in each shoulder. Likewise, we speak of the digastric even though there is a right and left digastric muscle.

The posterior belly, longer than the anterior belly, arises from the mastoid notch which is on the inferior surface of the skull, medial to the mastoid process of the temporal bone. The mastoid notch is a deep groove between the mastoid process and the styloid process. The mastoid notch is also referred to as the digastric groove or the digastric fossa.