Causes of shoulder pain include rotator cuff injury, tenosynovitis and shoulder joint dislocation, according to Healthline. Other causes of shoulder pain are rheumatoid arthritis, thoraci outlet syndrome, heart attack, frozen shoulder and torn cartilage, states Mayo Clinic.
Rotator cuff muscles and tendons facilitate shoulder stability and movement, explains Healthline. In most cases, injuries to the rotator cuff occur in the form of tears, tendinitis, strains and bursitis. They can be acute injuries, which usually result from previous injuries, or degenerative injuries, which occur as a result of prolonged overuse of the rotator cuff.
Tenosynovitis is a condition in which the tendon sheath, or synovium, becomes swollen as a result of an injury to the tendon, notes Healthline. When the synovium gets injured, it loses its normal ability to make synovial fluid, which lubricates tendons. As a result, the synovium swells, leading to shoulder pain. The causes of synovium injury include repetitive and prolonged activities, and strain. Medical conditions such as diabetes, gout and rheumatoid arthritis can also injure the synovium.
Shoulder joint dislocation occurs as a result of sudden or unbalanced impact to the shoulder as in the case of falling or being hit on the joint, says Healthline. When this happens, ligaments, nerves and blood vessels may suffer damage, causing intense shoulder pain.