Surgical anatomy of the radial nerve in the anterior compartment of the arm: relationship with the triceps aponeurosis

Abstract

Injury to the radial nerve is not an uncommon phenomenon in fracture displacement of distal humerus and its operative management as the nerve is immobile and superficial at its point of entry into the anterior compartment and in close proximity to humerus. Such injuries can be reduced by defining a ‘safe area’ for the radial nerve in relation to the triceps aponeurosis in the distal humerus. Radial nerve was dissected in 40 arms and distance of the nerve from triceps aponeurosis was measured at five sites; first one at the level of proximal or medial apex of aponeurosis, followed by four sites along its lateral border. These distances were analyzed to identify its location and to define a ‘safe area’ in relation to the triceps aponeurosis in the distal humerus. In majority of cases (67.50%), the point of entry of radial nerve into anterior compartment was at the level of proximal or medial apex at a mean distance of 2.11\u2009±\u20090.31 cm. The mean distance of radial nerve from the lateral border of triceps aponeurosis was 1.98\u2009±\u20090.60 cm with a range of 1.00–2.50 cm. The closest distance between the nerve and the aponeurosis was found to be 1.00 cm at the level of distal or lateral apex. The relationship between radial nerve and triceps aponeurosis is constant and easily reproducible. It is suggested that the rectangular zone immediately adjoining the lateral border of aponeurosis (<\u20091.00 cm) can be considered “safe” for soft tissue dissection while surgically approaching distal humeral fractures.