Many people who experience back pain are told they have 'muscle spasm' and while it's certainly true that this is present in many cases it unfortunately leads to the idea that muscles can spasm on their own for no reason.
So what causes a muscle to spasm or reflexively tighten? The spine is acutely sensitive to actual or perceived harm. The many intricate joints which comprise the column contain the extension of the brain and it's movement and stability is a finely controlled neuromechanical system. You've probably never considered this but muscular spasm (as distinct from cramping) never appears to occur anywhere else but the midline of the body - the spine - and the control of spinal position (an aspect of postural control) is the result of exquisitely complicated and integrated neuromuscular reflexes. Also part of this is a 'damage/instability warning' system which can trigger muscular splinting when it perceives that joint position or a joints components are threatened.
'Back pain' can be caused by many things. One off mild joint strains are common but should not be confused with chronic conditions which suggest repetitive injury due to a deconditioning of posture control. In these cases 'muscle spasm' or 'back pain' is not a diagnosis merely symptoms of poor neuromuscular control.
