💪 Sternocleidomastoid

Brian Lee
Jul 01, 2025
Reviewed

Summary

Origins: Manubrium of sternum; Medial third of 🦴 clavicle
Insertions: Mastoid process of the temporal bone; Superior nuchal line
Actions: Flexes neck when both sides contract; Rotates head to opposite side; Laterally flexes neck to same side; Assist to elevate the rib cage during inhalation