The Course and the Variations of Radial Nerve and its Muscular Branches in Human Fetuses’ Arms and Forearms

Aim: To determine the course and the variations of radial nerve and its muscular branches in human fetuses. Material and Method: Radial nerve dissections were made on the 200 arms and forearms of 100 fetuses (50 males and 50 females). Length, thickness and distance measurements were taken by the same person using a 0.01 mm sensitive digital compass. Results: In all arms, primarily, the medial branch of muscular branch was separating from radial nerve. This branch was originating from posterior superior part of radial nerve in 153 arms (76.5%) and anterior superior part of radial nerve in 47 arms (23.5%). On forearms it was observed that the first branches of radial nerve reached to the brachioradialis muscle and extensor carpi radialis longus muscle. It was found that the motor branch which innervates extensor carpi radialis brevis muscle exit from deep branch in 48% of the arms, from radial nerve (separating location of the deep and superficial branches) in 42% of the arms, and from superficial branch in 10% of the arms. Also it was observed, in 26% of the cases, that a muscular branch originated from radial nerve and reached to the inferolateral segment of brachial muscle. It was found that there was no relationship between radial nerve and humerus body’s upper (superiorly 0.18) and lover (inferiorly 0.17) parts. Conclusion: The course, muscular branches, innervation patterns and variations of radial nerve should be well known by the specialists especially dealing with the local surgery of this region. In the fetuses, the knowledge of the spiral course of the radial nerve on the posterior face of humerus is crucial to determine the operation approach point, and this area is less safer than adults in the fetuses, according to our results.