Entrapment of the ulnar nerve by the deep flexor-pronator aponeurosis.

A study of eight patients and 20 cadaveric limbs identified the deep aponeurosis of the flexor carpi ulnaris as a potential site for constriction of the ulnar nerve. The ulnar nerve passes through this aponeurosis approximately 5 cm distal to the medial epicondyle and 2 to 3 cm distal to the cubital tunnel. In two cases of isolated compression at this level, local decompression was successful in relieving the symptoms of ulnar nerve compression. Submuscular transposition is also effective because it places the ulnar nerve deep to this aponeurosis throughout its entire course.