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Anterior belly of digastric muscle

The anterior belly of the digastric muscle is a slender, ribbon-like muscle found in the anterior part of the neck, forming part of the suprahyoid muscle group. It plays a key role in jaw movement and swallowing, extending from the digastric fossa of the mandible to the intermediate tendon, which is tethered to the hyoid bone. Understanding its anatomy, innervation, vascular supply, and imaging features is essential for accurate diagnosis and surgical planning.

SYNONYMS

  • Anterior digastric

  • Anterior belly of digastricus

  • Venter anterior musculi digastrici

FUNCTION

  • Depresses the mandible (opens the mouth)

  • Elevates the hyoid bone during swallowing and speaking

  • Assists in stabilizing the hyoid bone

ORIGIN

  • Digastric fossa of the mandible (inner surface of the inferior border of the mandible, near the midline)

INSERTION

  • Intermediate tendon of digastric muscle (which is connected to the body and greater cornu of the hyoid bone by a fibrous sling)

NERVE SUPPLY

  • Mylohyoid nerve (branch of the inferior alveolar nerve from the mandibular division of the trigeminal nerve, CN V3)

ARTERY SUPPLY

  • Submental branch of the facial artery

  • Occasionally, small contributions from the mylohyoid branch of the inferior alveolar artery

VEIN SUPPLY

  • Submental vein (drains into the facial vein)

  • Anterior jugular vein (indirectly)

MRI APPEARANCE

  • T1-weighted: Intermediate to low signal intensity (similar to skeletal muscle)

  • T2-weighted: Normal muscle demonstrates relatively low signal intensity, but increased signal may indicate edema or pathology.

  • STIR (Short Tau Inversion Recovery): Fat suppressed, muscle appears with relatively low signal unless there is edema or pathology

CT APPEARANCE

  • Appears as a soft tissue density muscle band in the submental region, anterior to the hyoid bone

  • Well-defined margins, easily identified against adjacent fat planes

MRI images

Anterior belly of digastric muscle