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Sternocleidomastoid Muscle

The sternocleidomastoid muscle is a two-headed neck muscle, which true to its name  bears attachments to the manubrium of sternum (sterno-), the clavicle (-cleido-), and the mastoid process of the temporal bone (-mastoid). 

It is a long, bilateral muscle of the neck, which functions to flex the neck both laterally and anteriorly, as well as rotate the head contralaterally to the side of contraction. The muscle is closely related to certain neurovascular structures that pass through the neck on their way either to the head or to the periphery of the body.

Key Facts
Origin Sternal head: manubrium sterni
Clavicular head: middle of the clavicle
Insertion Mastoid process of the temporal bone, superior nuchal line of the occipital bone
Innervation Accessory nerve (CN XI), branches of cervical plexus (C1-C2)
Vascularization Occipital artery, superior thyroid artery (branches of the external carotid artery)
Actions Unilateral contraction: flexion of the neck, rotation of the head
Bilateral contraction: elevation of the head
Clinical relations Wryneck, torticollis

This article will discuss the anatomy, function and clincal correlates of the sternocleidomastoid muscle. 


Origins & Insertions

The sternal head originates from the manubrium sterni, while the clavicular head from the middle part of the clavicle. The insertion is the mastoid process of the temporal bone and the superior nuchal line of the occipital bone.


It is innervated by the accessory nerve (cranial nerve XI) and direct branches of the cervical plexus (C1-C2).

Landmarks & Relations

The muscle lies very superficially so that it is both easily visible and palpable. The carotid pulse may be felt in the middle third of the front edge. Under the sternocleidomastoid region runs a neurovascular bundle containing:

  • the common carotid artery (medial)
  • the internal jugular vein (lateral)
  • the vagus nerve (dorsal)
  • the cervical ansa

When putting a central venous catheter (CVC), the medial edge of the sternocleidomastoid muscle serves as a lead structure. Sensory branches of the cervical plexus merge dorsally to the muscle at the Erb’s point (punctum nervosum) which can be used as a place of puncture for local anesthesia.


A unilateral contraction of the sternocleidomastoid muscle flexes the cervical vertebral column to the same side (lateral flexion) and rotates the head to the opposite side. A bilateral contraction elevates the head by dorsally extending the upper cervical joints.

Recommended video: Sternocleidomastoid muscle
Origins, insertions, innervations and functions of the sternocleidomastoid muscle.

At the same time, it flexes the lower cervical column causing an overall bending of the neck towards the chest. If the head is fixed, it elevates the sternum and clavicle and, thus, expands the thoracic cavity (inspiratory breathing muscle).

Clinical Aspects

During pathological changes of the sternocleidomastoid the clinical picture of the wryneck occurs (bending of the head to the affected muscle and rotation to the healthy side). A classic example for this condition is the muscular torticollis, a tonic spasm of the sternocleidomastoid.

People with this disorder show difficulties swallowing, an extreme immobility of their throat, facial asymmetries and scoliosis. Approximately 0.5% of all newborn suffer from muscular torticollis, however the etiology remains unclear.

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Show references


  • D. Drenckhahn, J. Waschke: Taschenbuch Anatomie, Urban & Fischer Verlag/Elsevier (2008), S. 189
  • M. Schünke/E. Schulte/U. Schumacher: Prometheus – LernAtlas der Anatomie – Allgemeine Anatomie und Bewegungssystem, 2. Auflage, Thieme Verlag (2007), S. 292-293
  • W. Graumann, D. Sasse: CompactLehrbuch der gesamten Anatomie - Bd.2 - Bewegungsapparat, Schattauer Verlag (2003) S. 462-463
  • F. Hefti: Kinderorthopädie in der Praxis, 2. Auflage, Springer Verlag (2006), S. 117-120
  • E. Kennedy, M. Albert, H. Nicholson: The fascicular anatomy and peak force capabilities of the sternocleidomastoid muscle. Surgical and Radiologic Anatomy (2016), Springer-Verlag France, p. 1-17. DOI 10.1007/s00276-016-1768-9

Author & Layout:

  • Achudhan Karunaharamoorthy
  • Christopher A. Becker


  • First Illustration Gallery - Irina Münstermann, Paul Kim, Yousun Koh
  • Second Illustration Gallery - Yousun Koh, Paul Kim
  • Third Illustration Gallery - Irina Münstermann
  • Fourth Illustration Gallery - Paul Kim
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Related Atlas Images

Muscles of the anterior neck

Main muscles of the head and neck

Triangles of the neck

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