Shoulder girdle

802 Pectoral Girdle

Bulletin of the American Museum of Natural History (1881) (20254938750)

Shoulder girdle refers to the set of bones in the human body that connects the arm to the thorax (chest) and consists of two main parts: the clavicle (collarbone) and the scapula (shoulder blade). The shoulder girdle plays a crucial role in the movement and stability of the upper limb, allowing for a wide range of motion while also providing attachment points for numerous muscles and ligaments.

Anatomy

The shoulder girdle is composed of two clavicles and two scapulae. The clavicles are long, slender bones that lie horizontally at the base of the neck, connecting the arm to the body. Each clavicle articulates medially at the sternum (breastbone) at the sternoclavicular joint, and laterally with the acromion, a bony projection on the scapula, at the acromioclavicular joint.

The scapulae are flat, triangular bones located on the posterior side of the ribcage. They have several important features, including the glenoid cavity, a shallow socket that articulates with the head of the humerus (upper arm bone) to form the shoulder joint. Other notable features of the scapula include the acromion, the coracoid process, and the scapular spine, which serve as attachment points for muscles and ligaments.

Function

The primary function of the shoulder girdle is to provide support and stability for the shoulder joint, enabling a wide range of movements such as lifting, pushing, and pulling. The clavicles help to stabilize the shoulder laterally, while the scapulae provide a foundation for muscle attachment and movement. The unique structure of the shoulder girdle allows for a high degree of mobility in the shoulder joint, which is essential for the complex movements of the upper limb.

The muscles associated with the shoulder girdle, including the rotator cuff muscles, the trapezius, the pectoralis major, and the latissimus dorsi, play key roles in its movement and stability. These muscles work together to facilitate movements such as elevation, depression, protraction, retraction, and rotation of the scapula.

Clinical Significance

Injuries and disorders of the shoulder girdle are common and can significantly impact function and quality of life. Fractures of the clavicle are among the most frequent injuries, often resulting from falls or direct impacts. Dislocations of the acromioclavicular joint, known as shoulder separations, are also common, particularly in contact sports.

Conditions such as rotator cuff tendinopathy, bursitis, and frozen shoulder can affect the shoulder girdle's function, leading to pain, stiffness, and reduced range of motion. Treatment for these conditions may include physical therapy, medication, and in some cases, surgery.

See Also

• Human skeleton
• Musculoskeletal system
• Orthopedic surgery