pronatoren

Pronatoren, in anatomical terminology, are muscles that produce pronation, the rotation of a limb segment so that the palm or sole turns downward or backward relative to the anatomical position. In the context of the upper limb, the term most often refers to the forearm muscles that rotate the radius around the ulna to turn the palm downward.

The principal pronators of the forearm are the pronator teres and the pronator quadratus. The pronator teres originates from the medial epicondyle of the humerus and the coronoid process of the ulna, inserting on the lateral midportion of the radius. It acts mainly at the radioulnar joints to rotate the distal radius, contributing to pronation and elbow flexion. The pronator quadratus is a deep, flat muscle that lies across the distal forearm between radius and ulna; its fibers pull the distal radius over the ulna to produce rapid pronation and provide stability to the distal radioulnar joint.

Nerve supply for these muscles is primarily from the median nerve. Pronator teres receives innervation from the median nerve (C6-C7), while pronator quadratus is supplied by the anterior interosseous branch of the median nerve. Blood supply comes from branches of the ulnar and anterior interosseous arteries.

Functionally, pronators act as antagonists to the supinator muscles (including the supinator and, when the elbow is flexed, the biceps brachii) to control forearm rotation. Clinically, weakness or entrapment of the median nerve or the pronator muscles can affect pronation, as seen in conditions such as pronator syndrome or nerve injuries related to repetitive forearm use.