Musculotendinous variations about the medial humeral epicondyle

Abstract

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 less than .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.

Scratch Collapse Test Localizes Osborne's Band as the Point of Maximal Nerve Compression in Cubital Tunnel Syndrome

“…The predominant intraoperative finding of a thickened FCU aponeurosis or Osborne's band causing the entrapment for the ulnar nerve is not unique to our experience [4,7,8,[20][21][22]33]. Osborne's band, while tauter with elbow flexion, represents a good candidate for chronic compression because compression is commonly present at this site even in elbow extension.…”

“…The arcade of Struthers is a musculotendinous arch often quoted to exist between 3 and 10 cm proximal to the medial humeral epicondyle [12,26,29]. Existence of a true "arcade," however, is controversial, and Mackinnon and Dellon, in over 300 ulnar nerve surgeries never found the band to exist [7]. Despite this controversy, proximal dissection, at least 8 cm, is necessary as recurrence after failed transposition is noted to occur here presumably due to kinking of the nerve after incomplete release of the brachial fascia [18].…”

290 Surgical Procedures for Ulnar Nerve Entrapment at the Elbow: Physiopathology, Clinical Experience and Results

“…The increased vulnerability to compression of the nerve trunk at this level is conditioned by its anatomical relationships [3,5,7,10,13]: in fact, the nerve is running between the medial belly of the triceps muscle and humerus condyle. The aponeurosis, connecting to the intermuscular septum, and the muscle itself are closely following the nerve as far as it enters the trochlear groove, covered by a sheath of connective tissue extending to the two-folded belly of the¯exor carpi ulnaris.…”

“…The aponeurosis, connecting to the intermuscular septum, and the muscle itself are closely following the nerve as far as it enters the trochlear groove, covered by a sheath of connective tissue extending to the two-folded belly of the¯exor carpi ulnaris. Ulnar nerve compression may be related, besides external factors, to anatomical individual variations and it is a common cause of arm and hand pain, paraesthesias and weakness [7,13,14,37]. A correct preoperative evaluation and careful planning of the surgical procedure are essential for a good therapeutic result.…”

Separate muscle bundles of the flexor digitorum superficialis overlying the ulnar nerve

“…The muscles thought to be associated with ulnar nerve compression have been the hypertrophied medial head of the triceps brachii [17], and anomalous muscles such as the anconeus epitrochlearis and the anconeus epimedialis muscles [6,8,15] at the elbow, and a hypertrophied FCU in the lower part of the forearm [11]. Nonhypertrophied anomalous muscle bands that crossed the ulnar nerve were also found to cause compressive neuropathy around the wrist [16,22].…”