Scapulothoracic rhythm refers to the coordinated movement between the scapula and the thoracic cage during shoulder elevation, which is critical for maintaining shoulder joint stability and optimizing arm movement. This rhythm involves a specific ratio of motion between the glenohumeral joint and the scapulothoracic articulation, typically around 2:1, ensuring efficient upper limb function and reducing the risk of injury.

Scapulothoracic Rhythm

Coordinated Movement

The scapula, or shoulder blade, is a flat, triangular bone located in the upper back that plays a crucial role in shoulder mobility and stability by connecting the humerus (upper arm bone) with the clavicle (collarbone). It serves as an attachment site for multiple muscles, facilitating a wide range of arm movements and contributing to the overall function of the shoulder girdle.

Scapula

The thoracic cage, also known as the rib cage, is a bony structure that surrounds and protects the heart and lungs in the thoracic cavity. It consists of the sternum, ribs, and thoracic vertebrae, providing support and facilitating respiration through its flexible yet sturdy design.

Thoracic Cage

Shoulder elevation refers to the upward movement of the shoulder girdle, primarily facilitated by the trapezius and levator scapulae muscles. This movement is crucial for a wide range of activities, from lifting objects overhead to shrugging, and plays a significant role in posture and shoulder joint stability.

Shoulder Elevation

Shoulder joint stability is crucial for maintaining the functional integrity of the shoulder, preventing dislocations, and ensuring efficient movement. It relies on a complex interplay of static and dynamic stabilizers, including ligaments, the joint capsule, and the rotator cuff muscles.

Shoulder Joint Stability

Arm Movement

Ratio of motion

The glenohumeral joint, commonly known as the shoulder joint, is a ball-and-socket joint that allows for a wide range of motion, making it one of the most mobile joints in the human body. Its stability is primarily maintained by a combination of muscles, tendons, and ligaments, rather than the bony structures alone, making it susceptible to dislocations and injuries.

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