Anatomy of the Brachial Plexus: A Rare Variation in the Laboratory of Anatomy of Bamako (Mali)

The brachial plexus (BP), established by the lap twigs of the last four cervical nerves and the first thoracic nerve, assures the driving and sensory innervation of the thoracic member. We bring back a case of rare anatomical variation of the brachial plexus. It is a 34-year-old corpse dissected in the laboratory of anatomy of the Faculty of Medicine and Odontostomatology of Bamako in September 2017. The lap twig of the fourth cervical root (C4) participated in the constitution of the brachial plexus. The superior trunk was normally constituted. The average trunk was formed by the cervical roots C7 and C8 instead of only C7. And consequently the inferior trunk was constituted by the thoracic root T1. The posterior beam was only formed by the posterior branches of the superior and more average trunk. The medial beam was formed by all of the inferior trunk which did not give posterior branch for the formation of the posterior beam. The variations of the brachial plexus could entrain failures in the loco regional anesthesia of the brachial plexus.