The sternocleidomastoids (SCM) are the muscles in your neck that stick out when you turn your head, and you have two of them (one on each side of your neck). Although the name is awkward and difficult to pronounce, these muscles are named after the bones to which they attach.
Identifying the SCM (Biel, 2005)
- Origin*: The sternal head attaches to the top of the manubrium of the sternum (the bone to which your collar bone attaches at the center of your chest). The SCM also attaches to the medial one third of the clavicle, your collar bone.
- Insertion*: The SCM attaches to the mastoid process of the temporal bone and the lateral portion of the nuchal line of the occiput, right behind your ear.
- Action: Unilaterally*, the SCM flexes your neck to the same side, meaning that your right SCM will bring your right ear closer to your right shoulder. They also rotate your neck to the opposite side, so when the fibers of your right SCM shorten, your head will turn left. Bilaterally*, these muscles flex your neck (bringing your chin closer to your neck) and assist in elevation of the ribcage during inhalation.
- Innervation: The SCMs are innervated by the spinal accessory nerve, which originates in the upper spine and controls the motor functions of the SCM and trapezius. (Hacking and Wahba)
Causes of Injury or Tightness in SCM (Sternocleidomastoid Pain, 2017)
- Stress to the area, such as looking up for long periods of time, wearing clothing tight around the neck, etc
- Sudden pulls to the muscle, such as in cases of whiplash
- Chronic cough
- Structural issues that cause stress to the neck area
- Poor posture
Symptoms of an Injured or Tight SCM (Sternocleidomastoid Pain, 2017)
- Neck pain
- Swelling or pain in the throat upon swallowing food, caused by sternal division trigger points
- Tension headache or migraine caused my tension of neck muscles
- Disturbances in vision or eye issues, caused by trigger points in the sternal belly
- Disturbances in hearing, such as ringing or sudden deafness, caused by issues with the clavicular portion
- Pain in the upper chest
Trigger Point* Referral Pattern of the SCM (Riehl, 2002)
There are seven areas where the SCM may develop trigger points. This makes the SCM a muscle with one of the highest density of potential trigger points in the whole body. (Perry, 2013)
- Trigger points in the sternal head will radiate pain from the maxilla (jaw bone) into the cheek, arching over the eye brows, deep into the eye socket, in the upper chest and the back of the head.
- Trigger points in the clavicular head refer pain behind and inside the ear, in the same-side molar teeth, and over the forehead.
How to Relieve Stress From the SCM (Sternocleidomastoid Pain, 2017)
The most obvious way to relieve pain and tension from muscles is with regular massage. This will allow the muscle fibers to relax and take stress off of any structures that may be compressed. You may also find it useful to do some stretches and strengthening exercises for your neck and chest.
Keeping stress off of your neck is also a good way to make sure the muscles do not become strained, injured, or over stretched.
The single best way to prevent stress and injury from your muscles is to use proper posture. Improper posture overstretches certain muscles and tightens others, causing an imbalance in your boy and adding excessive amounts of stress that cause pain and immobility.
Bilaterally – An action in which both SCM muscles participate.
Insertion – The insertion of a muscle is the point at which the muscle attaches to a bone that is moved by that muscle. This point will be more distal (away from the core of the body) than the origin.
Origin – A muscle’s origin is the point at which the muscle attaches to a fixed, proximal (close to the core of the body) bone.
Trigger Point – An area of hyperactive tissue that sends excessive pain signals to the spine, which generally “confuses” the brain as to where the pain is coming from.
Unilateral – An action only requiring one SCM muscle.
Biel, A., 2005. Trail Guide to the Body, Third Edition. Book of Discovery, Boulder, CO. Pp.250
Hacking, C. and Wahba, M. et al. “Spinal accessory nerve.” [Internet]. Radiopaedia. [Accessed 2017 Jan 13]. Available from: https://radiopaedia.org/articles/spinal-accessory-nerve
Perry, L. “Sternocleidomastoid Trigger Points: Masters of the Migraine.” [Internet]. [2013 Jan 25]. Triggerpointtherapist.com. [Accessed 2017 Jan 13]. Available from: http://www.triggerpointtherapist.com/blog/sternocleidomastoid-pain-scm/sternocleidomastoid-trigger-points-migraine/
Riehl, S., 2002. Neuromuscular Therapy & Advanced Deep Tissue. Real Bodywork, Santa Barbara, CA. Pp 48.
“Sternocleidomastoid Pain.” Internet. [Updated 2017 Jan 13]. New Health Advisor. [Accessed 2017 Jan 13]. Available from: http://www.newhealthadvisor.com/Sternocleidomastoid-Pain.html
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