Experimental work on the functional anatomy of the shoulder has involved a study of the conditions involved in elevation of the arm. Movements of the upper limb are organised round a very special alignment of the scapulo-humeral joint whose geometric features and exact position have been determined. The ligaments of the joint play a major role in the controlling the attainment of this alignment. The value of this alignment in the physiology of the shoulder is demonstrated. A new terminology of shoulder movement is suggested.