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Posterior Belly of Digastric Muscle
Muscular System

Posterior Belly of Digastric Muscle

Venter posterior musculi digastrici

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Quick Facts

Origin: Mastoid notch of temporal bone.

Insertion: Intermediate tendon of digastric muscle.

Action: Depresses mandible; elevates hyoid bone.

Innervation: Digastric branch of facial nerve (CN VII).

Arterial Supply: Posterior auricular and occipital arteries.

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Origin

The posterior belly originates from the mastoid notch, which is found along the internal surface of the mastoid process of temporal bone.

Insertion

Both the anterior and posterior bellies of the digastric muscle insert into the intermediate tendon of digastric muscle. This tendon pierces the stylohyoid muscle and then passes through a fibrous sling that is attached to the hyoid bone.

The fibers of the posterior belly descend anteriorly before attaching to the intermediate tendon.

Key Features & Anatomical Relations

The platysma, sternocleidomastoid, stylohyoid, and longissimus capitis muscles, as well as the mastoid process of the temporal bone, sit superficial to the digastric muscle.

The fact that the anterior and posterior bellies have separate innervation reflects their embryological origins. The anterior belly is derived from the first pharyngeal arch and, thus, is innervated by the trigeminal nerve (CN V). The posterior belly of the digastric muscle is derived from the second pharyngeal arch and, therefore, it is innervated by the facial nerve (CN VII).

Actions

Overall, the digastric muscle is involved in multiple actions:

- depresses the mandible at the temporomandibular joint;

- elevates the hyoid bone (Standring, 2016).

References

Standring, S. (2016) Gray's Anatomy: The Anatomical Basis of Clinical Practice. Gray's Anatomy Series 41st edn.: Elsevier Limited.

Learn more about this topic from other Elsevier products

Digastric Muscle

ScienceDirect image

The digastric muscle is a paired muscle that inserts on the mastoid process, part of the temporal bone behind the ear, and the suture that joins the two halves of the lower jaw.

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