What causes muscle spasms?

Nerve impulses: All muscular contraction, be it smooth or skeletal muscle, are initiated by nerve impulses. These can be either voluntary or involuntary, as in muscle spasms. The most likely causes of these involuntary nerve impulses would be nerve root impingement of electolyte imbalance.

Myofascial Spasm: Muscle spasms can involve fascia, too. Fascia is the transparent casing of a muscle that allows glide. It's also the connective tissue around muscle subunits, bone, and in cells (ground substance). Kinks in fascia can tug at muscles in kinetic chain reactions. Muscle =myo, so myofascial might be a better name for the spasm. See www.Fasciacongress.Org for more info.

Mechanical Stress: To my mind, muscles react with spasm when stressed to their limit of expansion. Spastic muscles splint joints that are hypermobile from acute or chronic trauma. Immobile injured joints have reduced pain. Muscle spam is protective. Chronically spastic muscles develop painful trigger points. See my chronic pain board at quora.Com.

Muscle spasms: Can occur when muscle is overused or tired, especially if it was overstretched or if it has been held in the same position for long time. This causes muscle cell to run out of energy & fluid & becomes hyper-excitable, then develops a forceful contraction. Overuse is seen in athletes doing strenuous exercise in hot environment.

Various: Acute biomechanical stress and overuse, genetic causes, nutritional deficiencies, and chronic asymmetric body postures can all participate, in varying amounts, to occurrence of muscle spasms.