Spry Juncture, LLC
How to Evolve Gracefully
SCM (Sternocleidomastoid)
Region
Origin & Insertion
['Origin: Manubrium of sternum and medial clavicle', 'Insertion: Mastoid process of temporal bone and superior nuchal line']
Synergistic Muscles
['Scalenes', 'Longus colli']
Joints
['Cervical vertebral joints']
Primary Actions
['Neck flexion', 'Contralateral rotation', 'Ipsilateral lateral flexion']
Nerve & Spinal Segment
Spinal accessory nerve (CN XI), with contributions from C2-C3
Cervical plexus; C2–C3
Interesting
Acts on both head and neck position; easily palpable. [Saladin]
Reversal of Action
Lift sternum toward head in posture training
Common Dysfunctions
Torticollis, tension headaches, dizziness with head movement
How to Stretch
Tilt head to side and gently rotate away.
Trigger Points
How to Strengthen
Resist head flexion and rotation manually.
Concentric Action
Rotate head to opposite side, flex neck
Applications:
Commonly tight in forward head posture; retraining improves balance and airway
Eccentric Action
Control return from head rotation
Isotonic Action
Neck flexion with resistance band
Related Conditions
['Whiplash', 'Postural syndrome']
Isometric Action
Hold head in rotated or flexed position
Exercise Ideas
['SCM isometric holds', 'Chin-to-chest nods', 'Controlled rotation drills']