ANATOMY OF THE ULNAR NERVE AT THE ELBOW - POTENTIAL RELATIONSHIP OF ACUTE ULNAR NEUROPATHY TO GENDER DIFFERENCES

Men develop perioperative ulnar neuropathies more frequently than wome n. To determine the role of anatomical gender differences in the devel opment of these neuropathies, we performed several studies of the anat omy of the ulnar nerve, cubital tunnel, and elbow region. These studie s included detailed dissection of male and female embalmed and unembal med cadavers, ultrasound measurements of the tissue layers at the elbo w, and measurement of various dimensions of the coronoid process of th e ulna in multiple skeletal sets. No gross anatomical differences were found between genders regarding the course of the ulnar nerve through the upper limb. However, there was a strikingly larger (2-19 times gr eater) fat content on the medial aspect of the elbow in women compared to men, and the tubercle of the coronoid process was approximately 1. 5 times larger in men (P less than or equal to .002, rank sum test). O ur finding suggest that the tubercle of the coronoid process is a like ly area for external compression-induced ischemia of the ulnar nerve b ecause the nerve and its arterial supply (the posterior ulnar recurren t artery) are covered at the tubercle only by skin, subcutaneous fat, and a very thin aponeurosis of the flexor carpi ulnaris. Importantly, this tubercle is larger and the nerve and blood vessels passing by it are less protected by subcutaneous fat in men than in women. These two anatomical differences between men and women may contribute to the in creased frequency of perioperative ulnar neuropathy induced by externa l pressure at the medial aspect of the elbow in men. (C) 1998 Wiley-Li ss, Inc.