Muscle pain may be related to compression of the nerves that innervate the muscles, injury to the muscles themselves, and other precursors to disease.
Compression of the central nerves that innervate the muscles can lead to muscle pain in the innervated area, such as the common cervical and lumbar herniated discs, spinal stenosis, and pyriformis syndrome, which compresses the nerves.
Muscle pain can also be caused by peripheral nerve compression, such as carpal tunnel syndrome, elbow tunnel syndrome, and superior gluteal nerve entrapment syndrome.
Injury to the muscle itself can also cause pain such as chronic muscle strain, acute muscle pull after trauma, and bacterial infection of the muscle.
Generalized muscle pain can also be associated with colds and fevers, muscle fatigue from over-activity, and lactic acid buildup in the muscles.