Locomotive muscles contract and relax to facilitate movement of bones at the joints. Without the locomotive muscle groups, we could not move our bodies. When the muscles becomes altered, there is a tendency for the muscle fibers to become short and tight (muscle spasm). This change in muscle tone affects the joint and limits mobility.
Intrinsic muscles are located deep within our body. Simply put, these smaller muscles are underneath the large locomotive muscles and function to stabilize a joint. Without the proper function of these intrinsic muscle groups, the joints will stay under stress and the body will continue to try and compensate.