Internal rotation of the shoulder is the humerus rotating inward toward the chest or back—bringing the hand toward the abdomen or behind the back—primarily driven by subscapularis, pectoralis major, latissimus dorsi and teres major. External rotation rotates the humerus outward away from the body—moving the hand away from the abdomen—mainly using infraspinatus and teres minor.

Shoulder external rotation is the outward rotation of the upper arm at the glenohumeral joint, turning the forearm and palm away from the body. It primarily uses the infraspinatus and teres minor (with posterior deltoid assistance) and is important for throwing, reaching, and overhead tasks. Restriction may result from tight internal rotators, capsular stiffness, or rotator cuff pathology and is assessed clinically.

Test internal and external shoulder rotation with the patient seated or supine. Abduct the shoulder to 90° with the elbow flexed 90°. For external rotation, rotate the forearm backward; for internal rotation, rotate it forward (or reach the hand toward the opposite shoulder blade for internal). Measure range with a goniometer (axis at the olecranon, moving arm along the forearm) or use the Apley scratch as a functional screen.

The three standard shoulder X‑ray views are: anteroposterior (AP) — including true AP/Grashey for glenoid profile; axillary view — assessing glenohumeral joint alignment and dislocations; and the scapular Y (lateral) view — helpful for evaluating displaced fractures and shoulder dislocation. Together they provide orthogonal perspectives for fractures, dislocations, arthritis, and joint space assessment.

Pain with shoulder internal rotation can arise from rotator cuff (especially subscapularis) tendinopathy or tear, posterior capsule tightness, internal impingement, adhesive capsulitis (frozen shoulder), glenohumeral osteoarthritis, labral or biceps pathology, and cervical spine referral. Overuse, trauma, aging, poor posture or prior surgery increase risk. Evaluation includes history, exam and imaging to guide treatment.

Internal rotation example: rotating the arm or thigh toward the body—e.g., reaching behind your back to tuck into a waistband or turning the foot inward. External rotation example: rotating the arm or thigh away from the body—e.g., placing your hand on the back of your head or crossing one ankle over the opposite knee (figure‑4) so the knee points outward.