Musculotendinous variations about the medial humeral epicondyle

Anatomical variations in the musculofascial structures about the region of the medial humeral epicondyle were evaluated in 104 extremities in sixty-four cadavers. This study demonstrated presence of an Osborne's band in 77%, of some degree of ulnar subluxation in 25%, of an epitrochlearis anconeus muscle in 11%, the ulnar nerve beneath the medial head of the triceps in 24%, the medial head of the triceps within the floor of the cubital tunnel in 28%, the presence of a rudimentary supracondylar process in 1.5%, and a high origin of the pronator teres in 17% of the cadavers. There was a significant association between the presence of an epitrochlearis anconeus muscle and the ulnar nerve being completely covered by the medial head of the triceps muscle (p<.001). There was a significant relationship between the presence of the medial head of the triceps in the cubital tunnel and ulnar nerve subluxation (p.001). The high origin of the pronator teres may provide a proximal site for "double crush" syndromes of the median nerve.