Mouse Shoulder is a term that has been used to describe a specific collection of neck and shoulder symptoms noticed in people who use computers for prolonged periods. The shoulder and shoulder blade attach to the body by various muscles that insert into the spine, ribcage, neck, and base of the skull. Holding a mouse with the arm held away from the body causes these muscles to contract, as they support the weight of the outstretched arm. Sitting like this for several hours with no variation or relaxation can, in time, lead to pain and weakness.