Answer:
If the brachial artery were ligated at its origin, the profunda brachii artery would be primarily supplied by the collateral circulation, particularly through the branches of the axillary artery. The axillary artery gives rise to the subscapular artery, which, in turn, provides blood supply to the profunda brachii artery. The collateral circulation helps ensure blood flow to the deeper structures of the arm even if there is an obstruction or ligation of the main artery (brachial artery in this case).
