Sternocleidomastoid feels like a good starting off point for the muscle lesson series and I’ll tell you why: it was my favorite muscle as a child. Plain and simple. It wasn’t my favorite because I knew what it did, which I didn’t, but because it was fun to say. When I started massage school and all of my teachers called it SCM I was a little bummed, not gonna lie. Of course I now call it SCM! What a let down, right?
Before we jump into it, let’s talk a bit about how muscles attach to bones. Each muscle is encased in 3 layers of connective tissue called epimysium, perimysium, and endomysium. The layers then come together at either end of the muscle and form tendons. Tendons connect to bones to assist with movement when the muscle contracts. Muscle attachments are classified into two categories, origin and insertion. The origin is considered to be at the fixed bone with the insertion being the bone that moves with the muscle contraction. This isn’t always the case though. Some muscles cross more than one joint so the origin and insertion can “change” depending which joint you are moving. That isn’t to say the muscle attaches at different places, only that a different joint is moving. This can be a little confusing to remember but don’t worry too much about it. If you know the bony landmarks where the muscle attaches, you’re good to go.
On to SCM! It has two origin points, the sternal head attaches at the manubrium (the top portion of the sternum) and the clavicular head attaches at the medial (toward the midline, or centerline, of the body) portion of the clavicle. The muscle then comes together to attach at the insertion point, the mastoid process of the temporal bone. Generally speaking, it starts at the chest and then makes it way to behind the ear. You can see the muscle really "pop," and even grip it for some nice self-massage, when you turn your head to either side.
Now you might be asking yourself, "What movements does the SCM allow us to perform?" Because of how the muscle attaches, it pulls the head and neck into contralateral rotation, meaning that when the right SCM contracts, the head and neck turn to the left and when the left SCM contracts, the head and neck turn to the right. SCM also laterally flexes the head and neck (bringing your right ear to your right shoulder), flexes the neck forward, and helps to elevate the ribcage when breathing.
SCM gets put to use a lot during the day and so it’s important to take care of it. Trigger points can develop in the muscle which can create headache-like pains in the head and face and when the muscles get tight and shortened it can create issues within other areas of the body, like Upper Cross Syndrome. Massage can help manage headache symptoms and work to help correct postural imbalances but it's always best to find ways to mitigate those things from becoming an issue in the first place.
You can perform this simple stretch to help release some of the tightness that’s bound to occur. Lying on your back rotate your head and neck to the right making sure not to flex the neck. Go only as far as you can without feeling pain. Place your right hand under your head for support and the left above your ear and slightly over your temple. From here, create a little resistance with the left hand and try to rotate your head back to neutral against it. Keep rotating against the resistance for 7 seconds and then relax. Inhale, and on the exhale see if you can rotate your head to the right a little further. Repeat 2 more times. Remember, make sure that you aren't feeling any pain when performing this stretch and don't hold your breath.
There you have it, a quick little lesson on the sternocleidomastoid muscle. Let me know what muscle you want to learn about next and if you have any questions.