Sternocleidomastoid

Muscle Origin

Sternum and Clavicle to Mastoid Process of Temporal Bone.
Manubrium and medial portion of the clavicle.

Insertion

Mastoid process of the temporal bone, superior nuchal line.

The sternocleidomastoid is innervated by the accessory nerve of the same side. It supplies only motor fibres. The cervical plexus supplies sensation, including proprioception, via the ventral primary rami of C2 and C3. Wiki

Action

Laterally Rotate Head.anatomy-model-lateral-neck-024-edited 2

Contraction on both sides: Neck flexion. Contraction on one side only: Laterally flexes (side bends) to the same side and rotates to the other side. Sportsinjuryclinic.net

The function of this muscle is to rotate the head to the opposite side or obliquely rotate the head. It also flexes the neck. When both sides of the muscle act together, it flexes the neck and extends the head. When one side acts alone, it causes the head to rotate to the opposite side and flexes laterally to the same side (ipsilaterally). It also acts as an accessory muscle of respiration, along with the scalene muscles of the neck. Wiki

Innervation – Nerve control

Motor: accessory nerve.
Sensory: cervical plexus.

The accessory nerve is a cranial nerve that controls the sternocleidomastoid and trapezius muscles. As part of it was formerly believed to originate in the brain, it is considered the eleventh of twelve cranial nerves, or simply cranial nerve XI. Wiki

The cervical plexus is a plexus of the ventral rami of the first four cervical spinal nerves which are located from C1 to C4 cervical segment in the neck. They are located laterally to the transverse processes between prevertebral muscles from the medial side and vertebral (m. scalenus, m. levator scapulae, m. splenius cervicis) from lateral side. There is anastomosis with accessory nerve, hypoglossal nerve and sympathetic trunk. Wiki

Artery

Occipital artery and the superior thyroid artery

The occipital artery arises from the external carotid artery opposite the facial artery. Its path is below the posterior belly of digastric to the occipital region. This artery supplies blood to the back of the scalp and sterno-mastoid muscles, and deep muscles in the back and neck. Wiki

Antagonist muscles

 

Pictures of muscles

 

Trigger Point Referrals

 

Stretching description

 

Exercises

 

Injuries

 

Treatment

 

Additional Resources
Wiki

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