Unusual variations in the formation and branching pattern of brachial plexus

Anatomical variations in the formation and branching pattern of the brachial plexus are known. However, presence of various anomalies in the same cadaver, differing on the two sides is very rare. The present study aims to record the prevalence of such variations with embryological explanation and clinical implications. The study was carried out on thirty upper limbs from fifteen adult human cadavers. The brachial plexuses were exposed and dissected as per standard guidelines. The formation and branching pattern was observed. Numerous anomalies were observed in one cadaver, differing on the two sides. On the right side it was seen that the lower trunk did not divide and continued as medial cord. The posterior cord was absent and common pectoral nerve was formed. On the left side the main findings were absence of lateral cord, absence of musculocutaneousnerve and abnormal formation of Pectoral nerve. The medial cord was formed by anterior division of middle and lower trunk. A variation in branching pattern of posterior cord was also seen. Anomalous vascular relations were observed. Superior Thoracic artery was seen passing through the lateral and medial roots of Median nerve. Knowledge of these variations is important to anatomists, surgeons, anesthetists and radiologists.