Spry Juncture, LLC
How to Evolve Gracefully
Masseter
Region
📷 Masseter muscle animation small by Anatomography, via Wikimedia Commons, licensed under CC BY-SA 2.1 JP
Origin & Insertion
['Origin: Zygomatic arch', 'Insertion: Angle and lateral surface of mandible']
Synergistic Muscles
['Temporalis', 'Medial pterygoid']
Joints
['Temporomandibular joint (TMJ)']
Primary Actions
['Elevation of mandible', 'Protraction of mandible']
Nerve & Spinal Segment
Mandibular branch of trigeminal nerve (CN V3)
Cranial nerve; from trigeminal ganglion
Interesting
One of the strongest muscles by weight. [Gray’s Anatomy]
Reversal of Action
Anchor jaw and tilt head downward
Common Dysfunctions
Bruxism, jaw tension, TMJ pain
How to Stretch
Open mouth slowly with fingers on chin for light downward pressure.
Trigger Points
How to Strengthen
Jaw resistance exercises—press fist under jaw during mouth closing.
Concentric Action
Bite down forcefully
Applications:
Key in TMJ stability and rehab for chewing efficiency
Eccentric Action
Slowly open mouth against mild resistance
Isotonic Action
Chewing tough foods (e.g., gum or resistive chewing device)
Related Conditions
['TMJ dysfunction', 'Bruxism']
Isometric Action
Hold jaw closed against resistance
Exercise Ideas
['Isometric jaw press', 'Chewing resistance band', 'Controlled open/close']