Head and neck muscles (chewing, facial, and throat muscles)
Posterior belly of digastric
Musculus digastricus, venter posterior
- Origin
- Mastoid notch, medial to the mastoid process of the temporal bone
- Insertion
- Intermediate tendon connected via a fascial sling around the hyoid bone to the anterior belly of digastric
- Function
- Elevates the hyoid bone and assists lowering the lower jaw when the hyoid bone is fixed; important in initiating swallowing
- Innervation
- Facial nerve (CN VII), digastric branch
- Movement & chain
- Works via the intermediate tendon synergistically with the anterior belly and the other suprahyoid muscles to elevate the hyoid bone or, when the hyoid is fixed, to open the mandible.
- Palpation
- Palpable as a soft thickening just below and behind the earlobe, medial to the mastoid process, during active swallowing.
- Clinical
- An important anatomical landmark in the neck: together with the anterior belly and the mandible bounds Pirogoff's triangle, relevant in neck surgery.
- Segmental innervation
- Motor via the facial nerve (VII); no direct spinal segment.
- In clinical practice
- Elevates hyoid; paramount surgical landmark for accessory nerve, internal jugular vein, and carotid bifurcation during neck dissection.
- Region in the model
- Head and neck muscles (chewing, facial, and throat muscles)