A muscle spasm is a painful, involuntary movement or contraction of a muscle. A muscle spasm is also known as a muscle cramp. Muscle spasms and cramps are not the same as muscle twitching, which refers to very fine involuntary movements (fasciculations) of a small segment of muscle.Skeletal muscles are muscles attached to bones that you control to move your body.lthough we often think of skeletal muscle spasms or cramps, other kinds of muscle, such as smooth muscle, can spasm or cramp. Smooth muscles are found in the walls of hollow organs in your body, such as your stomach, bladder, and blood vessels, and play an important role in normal organ function.