GLOSSARY

The sternocleidomastoid (SCM) is a long, strap-like muscle at the side of the neck, clearly visible when the head is turned, and it divides the neck into anterior and posterior triangles.
Its name comes from its three attachments: the sternum, the clavicle, and the mastoid process.

Attachments and Innervation

• Origin: two heads, the sternal head from the manubrium and the clavicular head from the medial third of the clavicle.
• Insertion: the mastoid process of the temporal bone and the superior nuchal line.
• Nerve: the spinal accessory nerve (CN XI).

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