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Which movements can the shoulder’s ball-and-socket joint perform?

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The human hip and pelvis — ball-and-socket joint Anterior view of the hip and pelvis, showing attachment of ligaments to the femur, ilium, ischium, and pubis.

The shoulder's ball-and-socket joint, also known as the glenohumeral joint, is capable of several movements: flexion, extension, abduction, adduction, internal rotation, and external rotation.1

Flexion: Moving the arm forward, such as when reaching for an object.1
Extension: Moving the arm backward, like receiving a baton in a relay race.1
Abduction: Lifting the arm away from the body.1
Adduction: Lowering the arm toward the body.1
Internal Rotation: Rotating the arm inward, for example, when reaching into a back pocket.1
External Rotation: Rotating the arm outward, as seen in a tennis backhand stroke.1

The flexibility of the shoulder joint allows for a wide range of motion, contributing to various adaptations in different species. The rotator cuff muscles stabilize the humeral head, which is the ball portion of this joint.21