Response to injury
A muscle spasm
is often a response to injury to the muscle itself or the nearby bony or soft tissue structures.
Spasms are common in the posterior (back) of the shoulder, and usually involve the rhomboids, levator and/or trapezius muscles. Acute or repetitive strain can be the cause, or an injury or condition involving the lower cervical/upper thoracic spine can cause the nearby muscles to spasm.