Lesson
Forearm Joints
NOTES:
1.Forearm has proximal (pivot), middle, and distal (pivot) radio-ulnar joints
2.While the radius rotates about the ulna in pronation, the ulna is displaced laterally with respect to the radius
3.Biceps is stronger than supinator, but when elbow fully extended, biceps cannot aid in supination as its tendon run almost parallel to the shaft of the radius and so cannot produce radial rotation
4.Supination is more powerful than pronation, which is why screws have a right-handed thread, as most people are right-handed and would use right forearm supination to move the screw
5.Both pronation and supination are most powerful at 90º elbow flexion
6.Forearm pronation almost 180º without shoulder medial rotation. With humeral medial rotation, it becomes almost 360º.