Movements of the elbow and shoulder during pronation of the forearm

Abstract

It is known that medial and lateral movements of the lower end of the ulna occur during pronation and supination of the forearm, but there is little clear evidence as to where these movements originate. Twenty normal subjects pronated their forearm about either an undefined, lateral, or medial axis. Measurements were made from paired photographs taken at increments of 45° during the movement. Abduction of the ulna always occurred but its magnitude did not vary significantly with differing axes of pronation. During pronation about an undefined axis the abduction at the elbow produced a lateral movement of the ulna which was usually appropriate for the axis of pronation in use. Medial or lateral rotation of the humerus was used to increase or decrease the amount of lateral movement of the lower end of the ulna to suit the requirements of pronation about a medial or lateral axis.