Muscle cramps are common, affect virtually everyone and are mostly harmless. But that doesn't mean their occurrence is any less painful or the inconvenience they cause diminished. A muscle spasm ...

The exact cause of the spasm is not known ... muscle is located on the back of the neck and top of the shoulder.) The trapezius muscle now may be working more than it is used to.

These common causes of muscle spasms are usually minor conditions that easily resolve. But you should talk with your doctor if you suspect a medication is causing your muscle twitching.

Hemifacial spasm (HFS) is a neurological disorder manifested by twitching on one side of the face due to involuntary contractions of the eyelid and other facial muscles. It usually begins gradually ...

shoulder and upper back muscles causes these muscles to tear (on a microscopic level). Your body tries to prevent this tearing by forcing these muscles to knot up. This results in muscle spasms.