Arm external rotation
External or lateral rotation of the arm represents the movement of the humerus when an arm flexed to 90° at the elbow is externally rotated around the longitudinal plane of the humerus such that the hand moves away from the midline of the body. It is the opposite of arm internal rotation.
As with internal rotation, the degree of rotation is dependent on the degree of abduction. When the arm is adducted, medial rotation of 40-55° is possible. However, as the arm is abducted, this increases towards 70°.
It is produced by:
- infraspinatus
- teres minor
- deltoid (posterior fibers)
See also movements of the arm.
Siehe auch:
