Muscle
Sternocleidomastoid
Key neck landmark
High-yield
CN XI (spinal accessory). Contralateral rotation + ipsilateral tilt; bilaterally flexes the neck. Landmark for the neck triangles.
Overview
A strap muscle dividing the neck into anterior and posterior triangles that flexes the neck and rotates the head to the opposite side.
Reference facts
- Origin
Sternal head: manubrium. Clavicular head: medial third of the clavicle
- Insertion
Mastoid process and lateral superior nuchal line
- Action
Tilts the head to the same side and rotates the face to the opposite side; bilaterally flexes the neck
- Innervation
Spinal accessory nerve (CN XI); proprioception C2, C3
- Blood supply
Occipital and superior thyroid arteries
Clinical correlation
Congenital torticollis involves a fibrosed sternocleidomastoid.