shouldermuscle

The shoulder muscles, collectively known as the shoulder girdle or rotator cuff, are a group of muscles and tendons that surround the shoulder joint. This complex structure plays a crucial role in the movement and stability of the arm. The primary muscles involved are the supraspinatus, infraspinatus, teres minor, and subscapularis, which together form the rotator cuff. These muscles originate from the scapula (shoulder blade) and insert onto the humerus (upper arm bone).

The supraspinatus is responsible for initiating arm abduction, the movement of lifting the arm away from the body. The infraspinatus and teres minor work together to externally rotate the arm, turning it outward. The subscapularis is unique as it internally rotates the arm, turning it inward. Beyond these rotator cuff muscles, the deltoid muscle is a large, triangular muscle that covers the shoulder joint. It is responsible for a wide range of arm movements, including abduction, flexion (forward movement), and extension (backward movement).

The shoulder muscles are essential for everyday activities such as lifting, reaching, and throwing. They also provide dynamic stability to the glenohumeral joint, which is a ball-and-socket joint with a wide range of motion but inherently less stable than other joints. Injuries to the shoulder muscles, such as rotator cuff tears or tendonitis, can significantly impair function and cause pain. Strengthening and maintaining the health of these muscles through exercise is important for preventing injury and maintaining shoulder mobility and strength.