Functional Anatomy of the Flexor Pronator Muscle Group in Relation to the Medial Collateral Ligament of the Elbow

Abstract

To describe the relationship of the pronator teres, flexor carpi radialis, flexor digitorum superficialis, and flexor carpi ulnaris muscles to the medial collateral ligament at 30°, 90°, and 120° of elbow flexion, we dissected 11 cadaveric specimens. The flexor carpi ulnaris muscle is the predominant musculotendinous unit overlying the medial collateral ligament in the majority of cases and is the only one at 120° of elbow flexion. The flexor digi torum superficialis muscle is the only other significant contributor. The medial collateral ligament is the pri mary stabilizer of the medial elbow with elbow flexion greater than 30°, as in throwing. The flexor carpi ulnaris muscle, because of its position directly over the medial collateral ligament, and the flexor digitorum superficialis muscle, with its near proximity and relatively large bulk, are the specific muscles best suited to provide medial elbow support. This is especially relevant to overhand throwing athletes who encounter extreme valgus force across the elbow during the cocking and acceleration phases of the throwing motion. Exercise and condition ing of the medial elbow musculature, specifically the flexor digitorum superficialis muscle and the flexor carpi ulnaris muscle, may prevent injury or assist in rehabili tation of medial elbow instability, especially in overhand throwing athletes.