Sternocleidomastoid

Written by Oliver Jones

Last updated October 4, 2023 • 4 Revisions •

The sternocleidomastoid is a muscle of the anterolateral aspect of the neck.

  • Attachments: 
    • Sternal head originates from the manubrium of the sternum
    • Clavicular head originates from the medial third of the clavicle
    • Both heads attach to the mastoid process of the temporal bone and the superior nuchal line of the occipital bone.
  • Actions: Lateral flexion and rotation of the neck when acting unilaterally, and extension of the neck at the atlanto-occipital joints when acting bilaterally.
  • Innervation: Accessory nerve
  • Blood supply:
    • Upper third – Occipital artery
    • Middle third – Superior thyroid artery and external carotid artery
    • Lower third – Suprascapular artery

Fig 1- Lateral view of the neck. Note the two heads of the sternocleidomastoid

Premium Feature

3D Model

Premium Feature
Access this feature with premium.
Go Premium
Premium Feature

Dissection Images

Rate This Article