The radial nerve in the brachium: An anatomic study in human cadavers

Purpose: To explore the course of the radial nerve in the brachium and to identify practical anatomic landmarks that can be used to avoid iatrogenic injury during humerus fracture fixation. Methods: Data were collected from 27 adult cadaveric specimens, including 18 embalmed cadavers and 9 fresh-frozen limbs. Measurements were taken using osseous landmarks to define the relationship of the radial nerve and the posterior and lateral humerus. The extremities were studied further to determine the association of the radial nerve and anatomic landmarks on both longitudinal and cross-sectioned specimens. Results: A 6.3 cm +/- 1.7 segment of radial nerve was found to be in direct contact with the posterior humerus from 17.1 cm +/- 1.6 to 10.9 cm +/- 1.5 proximal to the central aspect of the lateral epicondyle, centered within 0.1 cm +/- 0.2 of the level of the most distal aspect of the deltoid tuberosity. The radial nerve lay in direct contact with the periosteum in all specimens, without evidence of a structural groove in the humerus in any specimen. On entering the anterior compartment, the radial nerve had very little mobility as it was interposed between the obliquely oriented lateral intermuscular septum and the lateral aspect of the humerus. As it extended distally, the nerve coursed anterior to the humerus and became protected by brachialis muscle at the level of the proximal aspect of the lateral metaphyseal flare. Conclusions: The radial nerve is at risk of injury with fractures of the humerus and with subsequent operative fixation in 2 areas. The first is along the posterior midshaft region for a distance of 6.3 cm 1.7 centered at the distal aspect of the deltoid tuberosity. The second is along the lateral aspect of the humerus in its distal third from 10.9 cm +/- 1.5 proximal to the lateral epicondyle to the level of the proximal aspect of the metaphyseal flare. The deltoid tuberosity is a consistent and practical anatomic landmark that can be used to determine the level of the radial nerve along the posterior aspect of the humerus during operative fixation from an anterior approach.