Figure 1b. Normal anatomy. (a) Axial T1-weighted magnetic resonance (MR) image demonstrates the popliteal artery (white arrow), popliteal vein (black arrow), and medial (white *) and lateral (black *) heads of the gastrocnemius muscle. (b) Arteriogram demonstrates the popliteal artery (*), sural arteries (black arrows), genicular arteries (white arrows), anterior tibial artery (white arrowhead), tibioperoneal trunk (black arrowhead), peroneal artery (white arrow with crossbar), and posterior tibial artery (black arrow with crossbar).