Sternocleidomastoid muscle

Sternocleidomastoid muscle (also known as SCM) is one of the largest and most distinct muscles in the neck. It is named after its attachment points - the sternum (breastbone), the clavicle (collarbone), and the mastoid process of the temporal bone of the skull.

Anatomy

The sternocleidomastoid muscle originates from two locations: the manubrium of the sternum and the clavicle. It travels obliquely across the side of the neck and inserts at the mastoid process of the temporal bone of the skull and the superior nuchal line. This muscle has a broad and strong attachment at its origin and a small, rounded and tendinous structure at its insertion.

Function

The primary actions of the sternocleidomastoid muscle are rotation of the head to the opposite side and flexion of the neck. When both sides of the muscle act together, it flexes the neck and extends the head. When one side acts alone, it causes the head to rotate to the opposite side and flexes the neck to the same side.

Clinical significance

Dysfunction of the sternocleidomastoid muscle can result in a variety of clinical conditions. These include sternocleidomastoid syndrome, which is characterized by a variety of symptoms including headache, facial pain, and dizziness. Another condition is torticollis, also known as wry neck, which is a condition in which the head is tilted toward one side, and the chin is elevated and turned toward the opposite side.

See also

• Neck muscle
• Torticollis
• Sternocleidomastoid syndrome

References

Sternocleidomastoid muscle Resources
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