Final answer:
The lateral arm flap receives its arterial blood supply from the posterior radial collateral artery, a branch of the deep brachial artery.
Step-by-step explanation:
The arterial supply to the lateral arm flap is provided by the posterior radial collateral artery, which is a branch of the deep brachial artery. This arterial network is responsible for delivering blood to the structures in the upper arm. The deep brachial artery itself arises from the brachial artery that supplies blood to the brachial region, dividing at the elbow into several branches, including the deep brachial arteries.
The lateral circumflex artery supplies blood to the deep muscles of the thigh and the ventral and lateral regions of the integument. In the case of a lateral arm flap, this artery is used to provide the necessary blood supply to the transplanted tissue in the lateral arm area.