Anatomic Variations of Ligaments and Muscles Related with the Ulnar Nerve Entrapment Syndrome in the Upper Arm / 대한해부학회지

Compressive neuropathy of the ulnar nerve occurs commonly at the cubital tunnel, but it can also be occurred by the anatomic variations of the structures on the ulnar nerve passage. This study was thus performed to clarify the variations of the ligaments and muscles, which can cause the ulnar nerve entrapment syndrome in the upper arm. One hundred arms of 50 Korean adult cadavers were used. The arcade of Struthers, a musculo-tendinous band from the medial head of the triceps brachii to the medial intermuscular septum, was observed in 34% of the cases. This arcade was mostly in a narrow-band shape, but a broad-band shaped arcade was sometimes observed. The internal brachial ligament was observed in 17% of cases. The epitrochleoanconeus muscle between the medial epicondyle and the olecranon was observed in 3% of cases. The ulnar nerve was wrapped or covered by the medial head of triceps brachii in 5% of cases. This study is expected to further the current understanding of the anatomic variations of ligaments and muscles on the ulnar nerve passage, and to be helpful data for the diagnosis and treatment of the ulnar nerve entrapment syndrome in the upper arm.

Ulnar Nerve Entrapment Syndrome by epitrochleoanconeus Muscle: A Case Report / 대한정형외과학회잡지

A forty-seven-year-old male miner complained of paresthesia over right hypothenar area and ring and little fiugers for 3 months. On physical examination and electromyography, ulnar nerve dysfunction below elbow was noted. Intraoperatively, an anomalous muscle, the epitrochleoanconeus muscle, was found between the triceps muscle and flexor carpi ulnaris muscle, but it was clearly distinguished from them. Resection of the muscle and medial epicondylectomy were performed. The epitrochleoanconeus muscle is an anomalous muscle which arises from the medial epicondyle of the humerus and inserts into the medial border of the olecranon. The reports on ulnar nerve entrapment syndrome by this muscle were rare. On 14 months follow up, the symptoms and signs were improved.