Pain and discomfort in the neck can come from many different structures, including muscles, joints, nerves, and surrounding connective tissues. One muscle that is frequently involved in neck pain and related symptoms is the sternocleidomastoid, commonly called the SCM. The SCM is a large, rope-like muscle located on each side of the neck. It runs from behind the ear down to the breastbone and collarbone. This muscle plays an important role in turning and tilting the head, hel