Sternocleidomastoid

The sternocleidomastoid, which is also known as the sternomastoid and as the sternocleidomastoideus, is a long muscle in the neck that rotates the neck and flex the head.

The points of origin and insertion, and the actions of the sternocleidomastoid muscle:

Origins:	Sternal Head: anterior surface of the upper sternum ('breastbone') Clavicular Head: medial third of the clavicle bone, which is also known as the 'collar bone'
Insertion:	Mastoid process, which is a conical prominence projecting from the undersurface of the mastoid portion of the temporal bone
Actions:	In general: Rotates the head Flexes the neck As also applies to other pairs of muscles of which one of the pair is located at either side of the neck, the actions of these muscles depend on how the combination operates, e.g. if both of the muscles that form the pair contract simultaneously or if only one of the pair (so, the muscle at only one side of the neck) contracts.

Extreme whiplash movements can cause damage to the sternocleidomastoid among other muscles.

This is one of the muscles of the head, neck, and face that is included on the syllabus of many courses in Indian Head Massage. As this is a popular therapy we have included several pages that may be of interest to students of Indian Head Massage. See, for example, the page about skeletal structures of the head and neck.

To view the location of the sternocleidomastoid muscle see the page about anterior muscles.