Relation of median nerve to brachial artery: variations, embryological basis and clinical significance

Brachial artery is the main artery supplying the upper limb. Variations in brachial artery are so many that it becomes a rule rather than an exception. A study was done to note the variations in the relation of median nerve to brachial artery. A total of 95 upper limbs (51 Right, 44 Left), with a mean arm length of 30.82 cms, were studied. In 11 of the limbs (11.57%) median nerve was noted to course posterior (deep) to brachial artery (Superficial Brachial Artery, SBA). Out of these 11 limbs, 6 (54.54%) belonged to right side and 5 (45.45%) belonged to left side. In 9 of these limbs (81.81%), median nerve coursed posterior to brachial artery in the middle 1/3 of the arm, whereas in 2 of the limbs (18.18%), crossing took place at the junction of middle and lower 1/3 of the arm. In 5 (45.45%) of these limbs brachial artery terminated normally, whereas in the remaining 6 (54.54%) trifurcation of brachial artery was noted. A significant association (χ=29.971, P=0.003) was found between the type of terminal branches of brachial artery and level of crossing of median nerve in relation to arm segment. This anatomical knowledge of variations in the relation of median nerve to brachial artery is of great clinical significance to general surgeons, vascular surgeons and orthopaedicians and helps in preventing iatrogenic injuries.