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 degrees, 90 degrees, and 120 degrees 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 degrees of elbow flexion. The flexor digitorum superficialis muscle is the only other significant contributor. The medial collateral ligament is the primary stabilizer of the medial elbow with elbow flexion greater than 30 degrees, 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 conditioning of the medial elbow musculature, specifically the flexor digitorum superficialis muscle and the flexor carpi ulnaris muscle, may prevent injury or assist in rehabilitation of medial elbow instability, especially in overhand throwing athletes.

Ultrasonographic Assessment of the Flexor Pronator Muscles as a Dynamic Stabilizer of the Elbow Against Valgus Force

“…In an anatomical study, Davidson et al 2) stated that the FCU and FDS were the predomi- nant musculotendinous units because of their position directly over the MUCL in the elbow flexion position. Recently, Otoshi et al 9) described that the upper part of the PT ulnar head was attached directly to the medial epicondyle via a thickened joint capsule just anterior to the AOL in all specimens and suggested that muscle activation of the PT directly increases the strain on the medial joint capsule via the humeral branch of the ulnar head.…”

Elbow anatomy and structural biomechanics

“…Due to the orientation and origin of the flexor-pronator muscles, it seems inherent that these muscles would provide a dynamic support to valgus stress across the medial elbow [37]. Specifically, the flexor carpi ulnaris and portions of the flexor digitorum superficialis lie directly over the anterior bundle of the medial ulnar collateral ligament [37].…”

Medial instability of the elbow: Findings on valgus load radiography and MRI in 16 athletes

“…All patients were treated with immobilization of the elbow in a long arm-cast for 4 weeks, followed by a total arm-strength rehabilitation protocol under supervision of a physiotherapist in which valgus load was avoided for 3 months. The flexor carpi ulnaris, flexor digitorum superficialis and pronator teres were strengthened to provide dynamic stabilization , Davidson et al 1995.…”