Rare Variation in the Course of C5 Root of Brachial Plexus

Variations in the formation of the upper trunk of the brachial plexus are relatively rare. Knowledge of its possible variation is useful to orthopedic surgeons dealing with the problems of cervical spine, anesthesiologists performing brachial plexus blocks and general surgeons performing lower neck surgeries. In this report, we present a variation in the formation of the upper trunk of the brachial plexus. The upper trunk was formed by the union of ventral rami of fifth and sixth cervical spinal nerves. The fifth cervical ventral ramus passed ventral to the scalanus anterior muscle, while the sixth cervical ventral ramus passed between the scalanus anterior and medius muscles. The upper trunk was formed at the lateral border of the scalenus anterior muscle.