An Uncommon Variation In The Formation Of Trunks Of The Brachial Plexus A Case Report.

Brachial plexus is the nerve plexus which gives innervation to the upper limb. Variation in the formation of brachial plexus is often reported. But variation in the trunk stage of brachial plexus is very rare. In this case report, we report an unusual variation in the formation of trunks of brachial plexus found in an elderly male cadaver during routine dissection. The upper trunk of brachial plexus was normal. The middle and lower trunks fused to form a common trunk. This was observed bilaterally. The upper trunk divided into anterior and posterior divisions. The common trunk divided into three divisions, anteromedial, anterolateral and posterior. The anterolateral division of common trunk joined with the anterior division of upper trunk and formed the lateral cord. The posterior division of common trunk joined with the posterior division of upper trunk and formed the posterior cord and the anteromedial division of common trunk continued as medial cord. The branches arising from the cords were normal.