Spasmodic torticollis signifies a spasm
in the neck muscles, forcing them to contract uncontrollably. This is thought
to be caused by an anomaly in the spinal accessory nerve, which innervates the trapezius and sternocleidomastoid muscles involved in certain neck and head movements. This condition can progressively force the head down on one side, which can be accompanied by uncontrolled and unwanted contraction of these muscles, as well as some pain in certain cases.