Pronation vs Supination
Pronation and supination are anatomical terms used to describe the rotation of the forearm and feet. These motions are important in shock absorption, balance, co-ordination, and propulsion of the body. In forearm, pronation and supination occur at synovial pivot joints at the proximal and distal ends of radius and ulna. Muscles involved in pronation and supination are attached to radius, which then moves around the fixed ulna of forearm.
What is Pronation?
Pronation rotates the hand to face downwards so that the radius and the ulna of the forearm are crossed. It puts the palm of the hand on a flat surface. For example, pronation involves when pouring something from a jug. Pronation involves two muscles; pronator teres and pronator quadratus. The pronator teres crosses the anterior forearm from the medial side of elbow and extends halfway down to lateral shaft of the radius. The pronator quadratus is located just above the wrist, passing transversely between the lower anterior shaft of the ulna and radius. Many pronation movements are made by the pronator quadratus alone. However, pronator teres is involved especially when an extra power is needed against resistance.
Supination turns the forearm to face upward that resulting in parallel ulna and radius. This motion is more powerful than pronation. Turning a screw is an example for supination. There are two basic muscles active in supination; namely, biceps brachii and supinator. The biceps brachii is involved in supination movements against resistance by pulling on the radial turberosity to rotate the radius. The supinator is involved in slow movements of supination, such as when arms hang by sides. The supinator originated from the lateral epicondyle of the humerus and adjacent areas of the ulna.
Pronation vs Supination
• In the forearm, supination of the radio-ulna joint makes the palm facing forward or upward, whereas pronation of the same joint makes the palm facing backward or downward.
• Supination is stronger than pronation.
• In the forearm, the muscles called pronator teres and pronator quadratus are active in pronation. In contrast, muscles called biceps brachii and supination are active in supination.
• Pronation makes ulna and radius crossed while supination results ulna and radius parallel.