Muscle Minute TUESDAY – Meet the Sternocleidomastoid

Stand and look in the mirror. Is your head sitting right in the center or is it turned a little bit right or to the left? When you lie on your stomach and place your head on the pillow, do you prefer to turn your head one way versus the other? One of the culprits of a head turn at rest or limitations in cervical rotation is tightness in the sternocleidomastoid (SCM). Let’s dive in.
Origin | anterior surface of manubrium (sternal head); medial one-third of clavicle (clavicular head) |
Insertion | mastoid process (temporal bone); superior nuchal line (occipital bone) |
Action | Unilaterally – contralateral cervical rotation, ipsilateral side bending; Bilaterally – cervical flexion; elevation of sternum and assists in forced inhalation. |
Innervation | accessory n. (CN XI), cervical plexus (C2-3) |
Antagonists | longus capitis, rectus capitis anterior (cervical extensors) |
The Real World Sternocleidomastoid
Wait. This muscle assists in breathing, too? Yes. If you are breathing in heavily, the sternal portion of this muscle activates to elevate the sternum and open up your rib cage. It also turns your head to the opposite side (rotation) and tilts it sideways (side bending).
But the most important thing about this muscle isn’t what it does, but rather what happens when it does too much of what it does. (I just felt like typing that sentence). Trigger points in this muscles radiate pain into the head and jaw. It has become known as the Master of the Migraine. Look at its trigger point pattern:

And it is one of two muscles implicated in temporomandibular dysfunction (TMD) that doesn’t directly attach to the jaw, the other one being the upper trapezius. If your jaw clicks when you open your mouth, you should check this muscle for trigger points.
Sit in front of a mirror and slightly turn your head in one direction. You should see the SCM stick out on the side you are looking away from.

Pinch the muscle between your thumb and index finger and pluck it like a string. Is it painful? Turn your head the other way and test the other side.
Here’s a short list of why this matters:
- If SCM is tight, it can elevate the medial clavicle, limiting movement during arm elevation. This may result in impingement syndrome.
- If the SCM is tight, it can alter head position causing imbalance of the jaw and fascial restrictions that may make your jaw pop and click when you open your mouth
- If the SCM is tight, it can mimic migraine pain.Â
- Severe trigger points may also make it feel difficult to swallow.
If you are clinician, checking the SCM for tightness in cervical, TMJ and shoulder patients and fixing what you find is key. If you find this on yourself, here is a simple self-treatment to release SCM trigger points.Â
Conventional thinking says: The SCM turns and tilts the head.
Real World Thinking says: SCM trigger points keep your head turned and/or tilted “and tightness may cause head, shoulder, neck and jaw pain. Take a moment to “pluck” this muscle.
Because nobody has time to be in pain.
Until next time…

Kind Regards,
MoveWell Academy
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