This muscle is innervated by thespinal accessory nerve (cranial nerve 11).
The SCM has two heads.
One originates from the collarbone/clavicle and the other from the breastbone/manubrium.
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One side can contract, or both sides can contract.
The SCM is part of a group of muscles known as the anterolateral neck flexors.
The scalenes are synergist (helper) muscles to the SCM.
They assist the SCM in turning and tilting both the head and neck.
An impairment or injury to the spinal accessory nerve can cause weakness or paralysis to the SCM.
Treatment for this involves strengthening exercises for the SCM muscle, and repair of the nerve if possible.
Synergist muscles help other muscles perform one or more functions.
Innervation is when an organ or body part is supplied with nerves.
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