Variation of the Radial Nerve, Ulnar Nerve and Axillary Nerve in Innervation of the Three Heads of the Triceps Brachii Muscle

Abstract

This study aimed to determine how frequently the radial nerve, ulnar nerve and axillary nerve provided innervation to the medial head, long head and lateral head of the triceps brachii muscle. A secondary goal of this study was to explore correlations between the distance from the point of insertion of each muscle head of the triceps brachii and where the innervating nerve enters the muscle belly. One hundred fifty‐four limbs from male and female preserved cadavers were dissected and examined during this study. The frequency of innervation by each nerve originating from the brachial plexus was recorded for the lateral head, medial head, and long head. The distance from the insertion of the triceps brachii muscle on the olecranon of the ulna to the insertion of the nerves on the muscle was measured in millimeters. The radial nerve was found providing innervation to the medial head, long head and lateral head of the triceps brachii in every limb examined. The ulnar nerve coursed through the medial head twenty times, but no branches were observed providing evidence of innervation. The axillary nerve was not observed providing innervation to any heads of the triceps brachii. The average distance from insertion of the heads of the triceps brachii on the olecranon of the ulna to the point of insertion of the innervating nerve branch on the muscle belly of the medial head, long head and lateral head was 128 mm, 183 mm and 170 mm respectively.