Variations of Cords of Brachial Plexus and Branching Pattern of Nerves Emanating From Them

Brachial plexus is complex network of nerves, formed by joining and splitting of ventral rami of spinal nerves C5, C6, C7, C8, and T1 forming trunks, divisions, and cords. The nerves emerging from trunks and cords innervate the upper limb and to some extent pectoral region. Scanty literature describes the variations in the formation of cords and nerves emanating from them. Moreover, the variations of cords of brachial plexus and nerves emanating from them have iatrogenic implications in the upper limb and pectoral region. Hence study has been carried out. Twenty-eight upper limbs and posterior triangles from 14 cadavers fixed in formalin were dissected and rare and new variations of cords were observed. Most common variation consisted of formation of posterior cord by fusion of posterior division of upper and middle trunk and lower trunk continued as medial cord followed by originating of 2 pectoral nerves from anterior divisions of upper and middle trunk. Other variations include anterior division of upper trunk continued as lateral cord and pierced the coracobrachialis, upper and middle trunk fused to form common cord which divided into lateral and posterior cords, upper trunk gave suprascapular nerve and abnormal lateral pectoral nerve and formation of median nerve by 3 roots. These variations were analyzed for diagnostic and clinical significance making the study relevant for surgeons, radiologists in arresting failure patients and anatomists academically in medical education.