Sternocleidomastoid Muscle: Location, Action and Trigger Points

Posted on 17 Oct 2010 21:25

By Eric Troy, Ground Up Strength

The sternocleidomastoid (SCM) is a muscle of the neck so-named because it originates on the sternum (sterno) and the clavicle (cleido) and inserts on the mastoid process1 (mastoid) which is an easily located bony prominence behind the ear. The muscles pass diagonally across the front and side of the neck beginning at the top of the sternum and ending behind the ear. This two-sided muscle is large and ropy, making it the most prominent muscle visible at the front of the neck.

The muscle is made up of two branches: The medial or sternal branch, which is directed superiorly, laterally, and posteriorly and the lateral or clavicular branch which is directed almost vertically upward.

The right side rotates the head to the left and flexes it to the right. The left side rotates the head to the right and flexes it to the left.2 Both sides together flex the neck and head forward. The SCM is also an important accessory muscle of inspiration (respiratory inhalation) and is highly active during costal (high chest) breathing especially during rapid breathing [3][4]. With habitually faulty forward head posture the SCM, along with the scalenes, may develop shortness. This will in turn place an overload strain on the muscles that help control forward neck flexion.

Sternocleidomastoid Origin, Insertion, and Action

Origin: Manubrium of the sternun and medial clavicle.

Insertion: Mastoid process, occipital prominence behind the ear.

sternocleidomastoid muscle photograph image

image by Rob Swatski[5]

sternocleidomastoid muscle photograph image

image by Rob Swatski[5]

Action: Both sides flex the head and neck forward. The left side causes rotation of the head to the right and lateral flexion to the left. The right side cause rotation of the head to the left and lateral flexion to the right.

Sternocleidomastoid Trigger Points Referred Pain and Symptoms and Causes

There is rarely pain present in the sternocleidomastoids themselves but they have the potential to refer a large amount of pain to areas of the head, face, throat, and sternum (see trigger point images below). Each head of the SCM, the clavicular and sternal, can have its own trigger points and so each must be treated separately, but each tend to refer pain upwards to the head, face, and jaws. The SCM may become tight and cause painful stiffness in the neck forcing the head to tilt to one side. This may indicate the presence of trigger points, which may be responsible for frequent headaches or ear pain (mistaken for an ear infection).

Headaches of a myofasical origin are referred to as myogenic headaches.3 and the pain from these types of headaches is most often felt in the lower back portion of the head, termed the occipital area. Trigger points in the trapezius muscle and various muscles of mastication can also contribute to myogenic headaches so should be treated concurrently.4

Sternocleidomastoid trigger points may be associated with trigger points in the jaw muscles that cause jaw and teeth pain. SCM triggered headaches along with jaw and teeth pain, for example, may mean that the SCM has generated secondary trigger points in the masseter muscles, which are causing the jaw and teeth pain.

Dizziness or balance problems, nausea, fainting, lacrimation (excess tear production,) blurred vision, eyelid jerking or droopy eyelid and visual disturbances have all been claimed to be a possible result of trigger points along the sternocledomastoid. A host of other systemic symptoms such as cold sweat on the forehead, distorted weight perception, excess mucus in sinuses, nasal cavities and throat, and chronic cough have also been attributed to them. According to Travell and Simons, impaired hearing was reported in some patients due to trigger points in the clavicular branch on the same side.1,7,8

Trigger points in the sternocleidomastoid can be activated by a tight or tense pectoralis major muscle as the clavicular head of the pec major pulls down on and forward on the clavicle which puts tension on the clavicular branch of the SCM. Any alteration in gait can cause problems in the SCM as well as the levator scapulae and scalenes as these muscles are active when trying to adjust to the gait alterations. Many other scenarios, of course, exist for the development of sternocleidomastoid trigger points. For more information refer to the resources at the bottom of the page.

Trigger Points of the Clavicular Branch

Trigger points in the clavicular branch of the SCM may cause deep ear-ache symptoms, toothaches of the back molars, pain behind the ear, and frontal head pain.

sternocleidomastoid muscle clavicular branch trigger points and referred pain pattern

Clavicular Branch Trigger Points

sternocleidomastoid muscle clavicular branch trigger points and referred pain pattern

Clavicular Branch Trigger Points

Trigger Points of the Sternal Branch

Trigger points in the sternal branch of the SCM can cause deep pain around the eyes, headaches behind the ear, at the top of the head, and over the eye. They may cause pain in the pharynx (throat) and the tongue when swallowing, giving you a "sore throat." They may also contribute to temporomandibular joint (jaw) pain along with the muscles of mastication. It is also possible for the pain to be referred downward to the top of the sternum.

sternocleidomastoid muscle sternal branch trigger points and referred pain pattern

Sternal Branch Trigger Points

sternocleidomastoid muscle sternal branch trigger points and referred pain pattern

Sternal Branch Trigger Points

Trigger Point Treatment

SCM trigger points are easily self treated and require only the fingers and thumb. Looking in the mirror may help visualize the two branches. To do so, slightly tuck the chin. You should be able to see one or both other the branches' origins on the sternum, with and indentation between them.

neck muscles image with sternal and clavicular branches of sternocleidomastoid labelled

SCM Sternal and Clavicular Branches

neck muscles image with sternal and clavicular branches of sternocleidomastoid labelled

SCM Sternal and Clavicular Branches

The sternal branch is the prominent branch closest to the front of the neck and the clavicular branch is behind. If you cannot visualize both of them place a few finger on the one you can see and roll backwards and forwards until you encounter a trough like area or indentation. This should allow you to locate the other branch. Once you have located a branch, squeeze it between the thumb and forefingers, massaging the kneading the muscle from top to bottom. Cover both branches, looking for particularly painful areas to concentrate on.

Only use as much pressure as you can tolerate. Each session should not last more than two minutes per side. Massaging the sternocleidomastoid may be extremely painful at first and may even bring on the referred pain symptoms, such as a headache. But the pain should get better quickly upon subsequent sessions and referred pain symptoms should begin to subside almost immediately. After the symptoms have gone away continue daily massage sessions for several days longer.

Be careful of the carotid artery which is located high up under the chin alongside the windpipe. This artery corresponds to the carotid pulse so if you can feel the pulse you are too close to the artery. The image below shows the internal and external carotid artery's location relative the sternocleidomastoid and other neck muscles, as well as the head anatomy. Massage of the SCM should be perfectly safe but as with any self treatment procedure, there are always risks. Consult your physician with any concerns you have.

Find anything you need for self trigger point treatment. There are many effective tools and informational resources available for personal use.

Self Stretch for the Sternocleidomastoid

The sternocleidomastoid can be stretched along with the trapezius muscle. To stretch the right trapezius and progress to a stretch of the SCM, from a seated position allow the head to fall to the left and then bend to the left a bit more. Keep the right hand tucked under the right hip so that the right shoulder does not rize during the stretch. While keeping the left side bend, allow the head to fall forward into flexion. Now turn the face to the left and use left hand to pull on the right side of the head to stretch the trapezius further. To stretch the sternocleidomastoid rotate the head to the right and then tuck the chin. A stretch should be felt in the SCM on the opposite side.

internal and external carotid arteries with neck muscles and sternocleidomastoid and head anatomy

Internal and External Carotid
Artery's Location Relative the
Sternocleidomastoid -image by
Patrick J. Lynch

internal and external carotid arteries with neck muscles and sternocleidomastoid and head anatomy

Internal and External Carotid Artery's Location Relative the Sternocleidomastoid
-image by Patrick J. Lynch

Sternocleidomastoid Stretch with Massage Ball Video

Strengthening the Sternocleidomastoids

There is actually no need to think about strengthening individual muscles of the neck. If the neck is exercised against resistance using all of its basic movements then all of the muscles will be appropriately worked and the SCMs will be heavily involved with forward flexion or rotary movements.

However for purposes of explanation, applying resistance to the front of the forehead to apply force posteriorly (toward the back of the head) and attempting to push the head forward against this resistance will work the sternocleidomastoids. This corresponds to the SCM's function in flexion of the neck. Placing the resistance against one side of the jaw to apply a rotational force and then attempting to turn the head toward this resistant force will work the SCM on the opposite side, corresponding to its role in rotating the head and neck.

The hand or other means of resistance can be used. Such as a weighted forehead strap, to work neck flexion. Also, a cushion can be placed against a wall and then leaned against with the forehead so that some of the body's weight must be supported, thus working neck flexion5. This exercise can be graduated to the ground. For rotation work only very light resistance should be used and there is little need for external resistance other than the hand. However, a partner can provide the resistance as well.

The most important point to remember in any neck strengthening exercise is that only isometric exercise should be used. Never actively forward or laterally flex, extend, or rotate the neck against resistance. No neck curls! This is a highly injurious activity and absolutely unnecessary for neck strengthening. The type of cervical injury that can be sustained during these types of exercises, even from just one incident, may never fully resolve. So no movement. Isometric only is the way to go.

The neck muscles and especially the sternocleidomastoid hypertrophy very easily for most trainees with just this kind of isometric work. So if your goal is to do reasonable strengthening of the neck and to have your neck look thicker it does not take a lot to achieve this for most.

This "Sternocleidomastoid Muscle: Location, Action and Trigger Points" page is provided by Ground Up Strength for information purposes only and should not take the place of professional medical advice. Although we have done our utmost to provide accurate and safe information, we are not medical professionals and the information on this page should not be taken as professional medical advice, or any other kind of medical advice. Any self-treatment undertaken by you is undertaken at your own risk.

1. Simons, David G., Janet G. Travell, Lois S. Simons, and Janet G. Travell. "Chp. 8: Masseter Muscle." Travell & Simons' Myofascial Pain and Dysfunction: the Trigger Point Manual. Baltimore: Williams & Wilkins, 1999. 329. Print.
2. Floyd, R. T., and Clem W. Thompson. Manual of Structural Kinesiology. Dubuque, IA: WCB/McGraw-Hill, 1998. Print.
3. Costa D, et al. “Participation of the sternocleidomastoid muscle on… [Electromyogr Clin Neurophysiol. 1994 Jul-Aug] - PubMed result.” Web. 17 Oct. 2010.
4. Kendall, Florence P., Et Al. Muscles Testing and Function with Posture and Pain. Baltimore, MD: Lippincott Williams & Wilkins, 2005. Print.
5. image by Rob Swatski, Assistant Professor of Biology, Harrisburg Area Community College - York Campus, York, PA
6. “Headache — Clinical Methods — NCBI Bookshelf.”
7. Davies, Clair. The Trigger Point Therapy Workbook: Your Self-treatment Guide for Pain Relief. Oakland, CA: New Harbinger Publications, 2004. Print.
8. Babak, Missaghi. “Sternocleidomastoid syndrome: a case study.” J Can Chiropr Assoc. 2004 September; 48(3): 201–205. Webcite.

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This page created 17 Oct 2010 21:25
Last updated 30 Jul 2017 22:49

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