Course of the innervation supply of medial head of triceps muscle and anconeus muscle at the posterior aspect of humerus (anatomical study).

INTRODUCTION: In elbow surgery; posterior side of joint has been described as the front door for accessing the elbow pathologies. Triceps splitting, triceps reflection, posterolateral Kocher, posteromedial Bryan-Morrey, modified MacAusland transolecranon approaches are the well known posterior surgical approaches. In the English literature, release and transposition of ulnar nerve on the medial side was fully described in posterior approaches. We believe that there was a need to identify the structures at the lateral aspect of the elbow while an iatrogenic injury may inversely effect an excellent radiological result. Therefore, we exposed the detailed innervation supply to the anconeus muscle and medial head of triceps muscle and tried to show possible denervation sites of these two structures during posterior approaches.

MATERIALS AND METHODS: This study was performed on 14 elbows in formalin-preserved 7 cadavers. We exposed the course of the innervation supply to the medial head of triceps muscle and anconeus muscle and tried to show possible denervation sites of these two structures during posterior approaches. The branching pattern of radial nerve innervating anconeus muscle and its deriving level from radial nerve was identified. Distance from a vertical line which is passing through lateral epicondyle to branching point was measured.

RESULTS: The mean distance of the branching point of the nerve to medial head of triceps muscle and anconeus was 168.3 mm (range 130.36-185.4). The nerve to anconeus muscle ran along the posterior aspect of the humerus from the horizontal line passing through lateral epicondyle at a distance of 142.20 mm (range 153.72-136.41) medial to olecranon and at a distance of 47.45 mm (range 77.13-30.14) lateral to olecranon.

CONCLUSION: Although splitting the fibers of triceps proximaly increases the exposure of the posterior humerus, innervation of the lateral portion of the medial head of triceps muscle and anconeus muscle may be jeoparadized. Therefore, surgeons who have interest in elbow surgery; (1) should revise the course of the nerve to medial head of triceps and anconeus muscle, (2) be aware of possible iatrogenic injury of the extensor muscles of the elbow via transtricipital approaches, (3) try to choose a more conservative posterior surgical approach.