A Rare Anatomical Variation in the Position of the Upper Trunk of the Brachial Plexus: A Case Report and Review of Literature

Anatomical variations of the brachial plexus may have not any clinical symptoms. One of these variations refers to the position of the roots and trunks of the brachial plexus. However, a good knowledge of this variation is very necessary in post-traumatic assessment, exploratory interventions, and administration of brachial plexus blocks in the interscalene space in order to surgical treatments. This report explains a case of variation in the position of the upper trunk of the brachial plexus which was observed in a male cadaver during routine dissection. Anatomically, the three trunks of the brachial plexus are originated from the C5-T1 spinal nerves, then, pass the interscalene space toenter the posteriortriangle of the neck. It is not usual that the upper trunk of the brachial plexus pierces the anterior scalene muscle, but in this report, it was observed that the upper trunk of the brachial plexus piercing the anterior scalene muscleunilaterally, then, was divided into two divisions. To exploratory interventions of the neck for brachial plexus nerve repair and surgical therapies, a good knowledge of the roots and trunks of the brachial plexus position helps surgeons and anesthetists prevent possible mistakes during surgery and diagnose the upper limb paresthesias.