Kinesiology: Shoulder Anatomy and Function

Shoulder Girdle

The bony structure that connects the arm to the torso, consisting of the sternum, clavicle, and scapula.

Scapular Plane

A plane of motion where the arm is positioned 30-45 degrees in front of the frontal plane, often used in functional activities.

Acromioclavicular Joint

The joint where the acromion of the scapula connects to the clavicle, providing muscle attachments and protecting underlying structures.

Glenohumeral Joint

A ball-and-socket joint that connects the humerus to the scapula, allowing a wide range of motion but is inherently unstable.

Labrum

A fibrocartilaginous structure in the glenoid cavity that deepens the socket, providing greater stability to the shoulder joint.

Scapulohumeral Rhythm

The coordinated movement of the scapula and humerus during shoulder elevation, typically occurring in a 2:1 ratio.

Rotator Cuff

A group of muscles and their tendons that act to stabilize the shoulder joint and facilitate its movements.

Serratus Anterior

A muscle crucial for scapular protraction and upward rotation, participating in shoulder stability.

Shoulder Stability

The ability of the shoulder joint to maintain its position and function without dislocating; compromised by excessive mobility.

Articular Disk

A structure in the sternoclavicular joint that enhances mobility by allowing slight movements of the clavicle.

Protraction

The forward movement of the shoulder blades away from the spine, enhancing functional reach and movement.

Retraction

The backward movement of the shoulder blades towards the spine, crucial for shoulder stability and posture.

Elevation

The upward movement of the shoulder girdle