• Abdominal aorta: originates at the aortic hiatus of the diaphragm, courses left of midline, anterior to the vertebrae, and terminates at the fourth lumbar vertebra.

• Aortic bifurcation: originates approximately at level of the umbilicus to form the common iliac arteries.

• Common iliac arteries: terminate at the origin of the internal iliac (hypogastric) and external iliac arteries.

• External iliac arteries: originate at the common iliac artery bifurcation; form the common femoral artery just proximal to the inguinal ligament.

• Lower extremity arterial system: originates with common femoral artery just inferior to the inguinal ligament.

• Abdominal aorta: lies to the left of the midline and courses along the lower abdomen with a slight posterior-to-anterior angulation. The aorta tapers as it moves toward its bifurcation where it has a diameter of approximately 1.5 cm in a normal adult. It gives rise to the iliac arteries, which course through the pelvis to form the common femoral artery at the level of the inguinal ligament.

• Common femoral artery: lies lateral to the common femoral vein and bifurcates into the profunda femoris (deep femoral) artery and the superficial femoral artery.

• Profunda femoris artery: lies lateral to the superficial femoral artery and gives rise to branches that supply the region of the femoral head and the deep thigh muscles. In a small percentage of patients, the profunda femoris will originate medially from the common femoral artery.

• Superficial femoral artery: lies anterior to the femoral vein and courses along the anteromedial aspect of the thigh. It courses deep as it enters the adductor canal in the distal thigh where it becomes the popliteal artery.

• Popliteal artery: within the popliteal fossa lies anterior and medial to the popliteal vein and gives rise to small geniculate branches. It branches into the anterior tibial artery and the tibioperoneal trunk.

• Anterior tibial artery: passes superficial to the interosseous membrane and courses anteriorly along the membrane. Distally, the anterior tibial artery courses along the anterior aspect of the tibia and becomes the dorsalis pedis artery after crossing the ankle joint.

• Tibioperoneal trunk: gives rise to the posterior tibial and peroneal arteries that supply the calf muscles.

• Posterior tibial artery: originates between the tibia and the fibula and courses along the medial aspect of the calf to a midpoint between the medial malleolus (ankle bone) and the heel.

• Peroneal artery: originates from the tibioperoneal trunk and courses obliquely along the medial aspect of the fibula. The peroneal artery lies deep to the posterior tibial artery and in close apposition to the fibula.

• The lower extremity arteries supply blood to the muscles of the thigh and calf. Normal resting muscle has a low flow demand. In contrast exercising muscle requires a significant increase in flow volume to oxygenate the tissues and carry away exercise-related toxins.

• In the resting state, normal muscle will exhibit a high-resistance blood flow pattern characterized by low diastolic flow. In contrast, exercising muscle has a low-resistance blood flow pattern, exhibiting constant forward diastolic flow.

• The normal vessel lumen should be echo-free.

• Using multiple scan planes, you should be able to image the vessel bifurcations, which may be off-axis.

• None.

• 5.0-MHz to 7.5-MHz linear array for thigh and calf in majority of patients.

• 2.0-MHz to 4.0-MHz curved array for abdominal aorta and iliac arteries and may be required to image upper thigh vessels in patients of large body habitus.

• Beginning with the patient in a supine position, obtain bilateral brachial systolic blood pressures using an appropriately sized blood pressure cuff (the width of the cuff bladder should exceed 20% of the limb diameter) and a continuous-wave Doppler transducer. Record the pressures on the worksheet (see the section on Data Documentation: Using Blood Pressures). In a similar manner, obtain bilateral ankle systolic pressure measurements from the dorsalis pedis and posterior tibial arteries by placing an appropriately sized blood pressure cuff immediately above the ankle. Record all tibial pressures on the worksheet and calculate the ankle/brachial index for both legs.

• Continue with the patient lying supine with the leg rotated outward and the knee slightly flexed in a frog-leg position to allow access to the common femoral artery and the popliteal fossa.

• Or have the patient lie prone with the feet slightly elevated on a pillow or rolled towel to allow access to the popliteal fossa.

• You may stand beside the examination table to scan the limb nearest to you. To ensure appropriate ergonomic positioning, make sure that your arm is supported and not at a right angle to your body and that the examination table has been raised to a height that is comfortable for you.