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Sternocleidomastoid (SCM): Learn Your Muscles

The sternocleidomastoid, or SCM, is one of the muscles that can be a real pain in the neck–literally. Since it connects your breastbone and collarbone to a notch on the back of your skull, its tightness can cause neck pain and restricted head movements. For most people though, the SCM only becomes a problem if you’ve been in an accident.

Location

sternocleidomastoid

Thanks to Virtual Sports Injury Clinic for the image.

There are two points of origin for the sternocleidomastoid. The sternal head originates on the anterior surface of the upper sternum, and the clavicular head originates on the superior surface of the medial one third of the clavicle. This means that one part of the muscle starts on the top part of the sternum, and the other part starts on the one third of your collarbone that is closest to your midline.

The sternocleidomastoid inserts on the mastoid process of the temporal bone. When you feel your skull just behind your ear, that outward bony lump is the temporal bone.

So, if you think about it, the SCM is not simply a neck muscle. Yes, it is a major muscle of your neck, but it also runs on a diagonal path. This means that it is one of the muscles that connects the front plane of your body to the back plane.

Function

When both sides of the SCM contract, the head moves forward and the neck flexes. That’s if you’re moving the insertion to the origin. Think about the opposition movement and, when you move origin to insertion, the sternum (breastbone) lifts. Wherever the sternum goes, the rib cage will follow. This movement is most noticeable in deep inhalation.

If only one side of the SCM is contracted, the head will tilt toward the same side as the working muscle. Also, it will turn your head to the opposite side. It could also turn your head to the opposite side and slightly tilt it upward as the muscle contracts.

Common Dysfunction

This muscle is commonly tight and dysfunctional for many people. If you feel like you’re someone who carries a lot of neck tension, this muscle could be one of the culprits. Even with a dysfunctional SCM, you won’t notice a significant inconvenience.

Maybe your head rotates better toward one side than the other, or maybe you feel tightness along the path of the muscle. Sometimes this tightness can cause headaches or neck pain.

If you have significant issues with your SCM, it’s more likely that you have had an injury or accident. Extreme whiplash can cause significant issues with several of your neck muscles. As someone who has broken her neck, I can attest that the SCM therapy after the healing process is incredibly challenging. This nagging muscle requires constant strengthening and stretching, and slacking in your exercises only results in pain.

Restoring or Maintaining Health

If you believe you have injured your sternocleidomastoid, please talk to your doctor. A doctor can order all of the appropriate imaging, medicine, and therapy for you to make a quick and complete recovery. For those who have been in an accident or have been injured, it is particularly important for you to see a doctor. Once you are released, make sure you have a script for physical therapy. A physical therapist will make sure you are working the muscle correctly.

For those who are simply wanting to keep a strong, healthy SCM, here are some suggestions:

  • Regularly massage this muscle. You can even rub the SCM while you’re performing a stretch.
  • Look down. This works both sides of the sternocleidomastoid at the same time.
  • Look to the right and left. When you deeply engage the SCM, the head will tilt upward after rotating. Remember, if you’re looking to the right, it’s the left SCM working.
  • Try other neck stretches. There is a program called Active Isolated Stretching that I use frequently for my clients. You hold stretches for short amounts of time to help increase the strength and flexibility of the muscles. Here is a link to an instructional video.

More Information

I consulted The Concise Book of Muscles by Chris Jarmey. Recently, the book updated to its third edition. I love this as a quick resource.

If you’re wanting more in-depth information, I recommend Flash Anatomy Muscles Flash Cards. I also used these as a resource. If you really enjoy anatomy and want a tool to help you locate specific muscles correctly, I highly recommend these flash cards. I turn to them any time a client comes in with pain.

What’s your favorite way to strengthen your sternocleidomastoid? Let us know in the comments below.

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About Sarah Stockett

Hi! I'm Sarah, and I'm a certified Pilates and yoga instructor with a passion for pain relief. When I'm not working with clients, I'm researching the best ways to get rid of pain. Do you want to learn how to practice yoga and Pilates safely in your own home? Or, do you want to know all my tips and tricks for pain relief? Join my mailing list and receive free goodies to help you.

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