Muscle
Digastric
Two bellies linking the jaw and hyoid
High-yield
The anterior belly develops from the first pharyngeal arch and receives the mylohyoid branch of V3. The posterior belly develops from the second arch and receives CN VII.
Overview
The digastric has an anterior belly beneath the mandible and a posterior belly running from the temporal bone. An intermediate tendon joins them near the hyoid. Their different embryological origins explain their different motor nerves.
Reference facts
- Origin
- Anterior belly: mandibular digastric fossa. Posterior belly: temporal bone mastoid notch
- Insertion
- The bellies meet at an intermediate tendon held near the hyoid by a fibrous sling
- Action
- Raises the hyoid during swallowing; with the hyoid fixed, helps lower the mandible
- Innervation
- Anterior belly: nerve to mylohyoid (V3). Posterior belly: facial nerve (CN VII)
- Blood supply
- Anterior belly: submental branch of the facial artery. Posterior belly: occipital and posterior auricular branches
Clinical correlation
The posterior belly helps orient upper-neck anatomy: major carotid vessels, the internal jugular vein and the hypoglossal nerve lie deep to this region. Anatomical variation limits the reliability of any single landmark.
Frequently asked questions
What does the digastric do?
Raises the hyoid during swallowing; with the hyoid fixed, helps lower the mandible.
What nerve innervates the digastric?
Anterior belly: nerve to mylohyoid (V3). Posterior belly: facial nerve (CN VII).
Where does the digastric attach?
Origin: Anterior belly: mandibular digastric fossa. Posterior belly: temporal bone mastoid notch. Insertion: The bellies meet at an intermediate tendon held near the hyoid by a fibrous sling.
What is the blood supply of the digastric?
Anterior belly: submental branch of the facial artery. Posterior belly: occipital and posterior auricular branches.