Digastric Muscle

Description[edit | edit source]

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.[1]

Origin[edit | edit source]

anterior belly - digastric fossa (mandible); posterior belly - mastoid process of temporal bone

Insertion[edit | edit source]

Intermediate tendon (hyoid bone)

Nerve Supply
[edit | edit source]

anterior belly - mandibular division (V3) of the trigeminal (CN V) via the mylohyoid nerve; posterior belly - facial nerve (CN VII)

Blood Supply[edit | edit source]

anterior belly - Submental branch of facial artery; posterior belly - occipital artery

Function[edit | edit source]

When the digastric muscle contracts, it acts to elevate the hyoid bone.

If the hyoid is being held in place (by the infrahyoid muscles), it will tend to depress the mandible (open the mouth).

Action[edit | edit source]

Opens the jaw when the masseter and the temporalis are relaxed.

Trigger Point Referral Pattern[edit | edit source]

 The anterior and posterior bellies of digastric may contain an MTP. The MTP in the posterior belly may refer pain over the mastoid process and occasionally to the throat under the chin . The anterior belly refers to the lower central incisors and to the alveolar ridge below.[2]                                                                                                                                               

Palpation[edit | edit source]

Direct external palpation of posterior digastric is difficult due to the depth of the muscle. The anterior digastric is examined by identifying the lateral margins of the hyoid, and then palpating the inferior surface of the mandible by placing the thumbs on either side of the midline. To confirm the location of the anterior digastric, the patient is requested to swallow; a prominence of the anterior belly can be palpated under the thumb tips as the hyoid is drawn superiorly.

Length tension testing[edit | edit source]


Strength Testing[edit | edit source]


Treatment[edit | edit source]



Recent Related Research (from Pubmed)[edit | edit source]




References[edit | edit source]