Localizing the course of the radial nerve based on anatomical landmarks: A cadaveric study

Surgeons treating humeral shaft fractures must be able to reliably locate the radial nerve in the posterior arm to limit iatrogenic injury. This study aims to improve the understanding of radial nerve anatomy by increasing the sample size, comparing bilateral upper extremities, and analyzing the impact of sex on its location.

Twenty-five pairs (n = 50) of fresh cadaveric upper extremities were studied with the cadaver in the lateral position. The shoulder was abducted and internally rotated and the elbow flexed to 90° and supported, as done intraoperatively. A triceps-splitting approach was performed and the radial nerve was identified in situ. Distances were recorded, using an electromagnetic digitizer, taken from the medial epicondyle to the proximal and distal edges of where the radial nerve crossed the posteromedial border of the humerus. Two measurements were taken on the ipsilateral extremity using the lateral epicondyle and posterolateral border of the humerus as reference points. The contralateral extremity was measured using the same protocol. A midpoint between the proximal and distal edges of the radial nerve was then calculated for its crossing on both the medial and lateral borders of the humerus.

The radial nerve, on average, crosses the posterior humerus 17.1 cm and 12.5 cm proximal to the medial and lateral epicondyles, respectively. There was no difference when matched pairs were compared bilaterally. The radial nerve was between 0.93 cm and 1.06 cm closer to the epicondyles in females than males, a statistically significant difference.

The increase in sample size and comparison between sexes provides a more reliable location for where to expect the radial nerve in the posterior arm. This improved understanding may help surgeons better anticipate the location of the radial nerve during operative repair of adjacent injured structures, thereby reducing the risk of iatrogenic nerve injury.

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