Utåtrrotation

Utåtrrotation, or external rotation, is the movement of turning a body segment around its longitudinal axis so that the distal part moves away from the midline of the body. In humans, external rotation is most commonly described for the shoulder (glenohumeral joint) and the hip (acetabulofemoral joint), but other joints can also perform outward rotation.

In the shoulder, external rotation occurs when the arm rotates outward relative to the torso, often demonstrated with the elbow flexed or by moving the arm away from the body's midline. The primary muscles contributing to shoulder external rotation are the infraspinatus and teres minor, with additional assistance from the posterior portion of the deltoid. In the hip, external rotation turns the leg outward, involving deep lateral rotators such as the piriformis, gemelli, obturator internus and externus, quadratus femoris, as well as the gluteus maximus.

Measurement and function: Clinically, external rotation ROM is assessed with a goniometer to gauge joint mobility. External rotation supports various daily activities and athletic movements, contributing to reach, gait, balance, and joint stability.

Clinical relevance: Limited external rotation can indicate pathology or stiffness. In the shoulder, conditions such as adhesive capsulitis (frozen shoulder) or rotator cuff pathology can reduce external rotation. In the hip, tight external rotators, impingement, or neuromuscular issues can affect ROM and function. Strength balance between external and internal rotators is important for joint stability.

See also: internal rotation.