Sternocleidomastoid
Musculus sternocleidomastoideus
MuscularSuperficial musclesWhole bodyLeft and right
View left in 3D View right in 3D
- What it is
- Strap muscle crossing the side of the neck obliquely, from the mastoid process and superior nuchal line down to two heads: a rounded tendinous sternal head on the manubrium and a flat fleshy clavicular head on the medial third of the clavicle.
- Function
- Acting alone it turns the face to the opposite side and tilts the head to the same side; both together flex the neck and help lift the thorax in forced inspiration.
- Size
- About 16 cm long and 3–4 cm wide at mid-neck.
- Clinical note
- Fibrosis of it in infancy causes congenital torticollis (wry neck); it divides the neck into the anterior and posterior triangles.