Spry Juncture, LLC
How to Evolve Gracefully
Digastric
Region
📷 Digastricus by Uwe Gille (modified from Image:Gray385.png), via Wikimedia Commons, in the Public domain
Origin & Insertion
['Anterior belly origin: Digastric fossa of mandible', 'Insertion: Intermediate tendon to hyoid bone']
'Posterior belly origin: Mastoid notch of temporal bone',
Synergistic Muscles
['Mylohyoid', 'Geniohyoid']
Joints
['Temporomandibular joint (indirectly)']
Primary Actions
['Depresses mandible', 'Elevates hyoid during swallowing']
Nerve & Spinal Segment
Mylohyoid branch of mandibular nerve (CN V3)
Posterior Belly: Facial nerve (CN VII)
Cranial nerve; Trigeminal ganglion
Posterior Belly: Cranial nerve; Facial nucleus in pons
Interesting
One muscle with dual innervation; functions in swallowing and speaking. [Moore's Anatomy]
Reversal of Action
Elevate hyoid during swallowing
Common Dysfunctions
Difficulty initiating swallow, jaw movement asymmetry
Posterior Belly: Impaired hyoid elevation, weak laryngeal elevation
How to Stretch
Open jaw wide and tilt head slightly back to stretch anterior neck.
Trigger Points
How to Strengthen
Resisted jaw depression using fingers under chin.
Concentric Action
Depress mandible during mouth opening
Applications:
Used in dysphagia rehab and swallowing coordination
Eccentric Action
Control jaw closing against light resistance
Isotonic Action
Repeated jaw opening against gravity
Related Conditions
['TMJ disorders', 'Dysphagia']
Isometric Action
Hold mandible in slightly open position
Exercise Ideas
['Jaw depression with resistance', 'Hyoid elevation holds', 'Swallow and hold drill']