Allen test part 1

Anatomy

The blood supply to the arms is supplied by the right and left subclavian arteries with arising from the brachiocephalic trunk fron the aorta. The subclavian arteries then run beneath the clavicle and are referred to as  axillaries arteries as it is reaches the axilla. From there, the axillary artery which supply blood to the upper arm will continue to travel to the antecubital fossa where it divides into radial and ulnar arteries. The radial and ulnar arteries then will supply blood flow  to the forearm and eventually to the hand. The radial artery runs along the lateral aspect of the forearm between the brachioradialis and flexor carpi radialis muscles. At the wrist, it splits into superficial and deep palmer branches. The ulnar artery runs along medial aspect of the forearm and at the wrist runs through Guyon's canal its split into its deep and superficial branches. These arches form the basis of the collateral blood flow to the hand.