To appreciate how helpful ultrasound is in evaluating the lower extremities for abnormalities, it is important to be proficient in the basic anatomy of the lower extremity arteries.
There are five arteries in each leg that you’ll examine in a routine ultrasound study:
- Common femoral artery (CFA)
- Superficial femoral artery (SFA)
- Popliteal artery
- Posterior tibial artery (PTA)
- Dorsalis pedis artery (DPA)
The lower extremities’ deep veins run adjacent to arteries of the same name which can help identify the arteries on ultrasound.
The common femoral artery (CFA)
The saphenofemoral junction (SFJ) in the groin area is adjacent to the CFA. On ultrasound, you can find the SFJ next to the CFA with the common femoral vein (CFV) just inferior. This appearance is referred to as the Mickey Mouse sign.
The CFA is inferior to the inguinal ligament and receives aortoiliac inflow. On ultrasound, a normal CFA has smooth walls and a black lumen.
At the CFA bifurcation, the CFA divides into two branches:
- Profunda femoris artery (PFA)
- Superficial femoral artery (SFA)
The profunda femoris artery (PFA)
The PFA, formerly known as the deep femoral artery, dives deep off of the CFA bifurcation and branches into collaterals in the thigh. Due to its deep anatomical location, it is not routinely examined on ultrasound past the CFA bifurcation. The PFA and its branches are better evaluated by computed tomography (CT), if needed.
The superficial femoral artery (SFA)
The other branch off of the CFA bifurcation, the SFA, is also known as the femoral artery. Rather than use the general terminology, it is more useful to clarify whether you’re referring to the common femoral artery, the profunda femoris artery, or the superficial femoral artery. The SFA travels from the CFA bifurcation down the medial thigh to the knee.
The popliteal artery
The SFA becomes the popliteal artery at the posterior knee. The above-knee popliteal artery starts at the distal adductor canal (where the thigh becomes the knee), and the below-knee popliteal artery extends to the bifurcations of the calf arteries at the distal popliteal fossa.
The popliteal is the only artery where you regularly see the vein located above the artery on the ultrasound screen.
The posterior tibial artery (PTA)
The distal popliteal artery splits into the anterior tibial artery (ATA) and the tibioperoneal trunk (TPT) at the distal popliteal fossa. The TPT immediately splits into the peroneal artery and PTA, which both travel the length of the inner calf to the ankle.
The dorsalis pedis artery (DPA)
The ATA follows the lateral shin and becomes the DPA at the ankle. Then, it forms the pedal arch of the foot. The DPA can be evaluated in an ankle-brachial index test, known as the ABI test.
The three-vessel runoff
The peroneal artery, the PTA, and the ATA are commonly referred to as the three-vessel runoff. The three-vessel runoff isn’t typically examined throughout the entire calf with ultrasound.
By comparing the ultrasound duplex findings at the popliteal artery to the waveforms obtained at the ankle, we can determine the presence and severity of a disease in the calf. If there is a concern from this comparison, a CT scan is ordered for a more efficient and detailed assessment of the runoff vessels.
That’s it for now. If you want to improve your understanding of key concepts in medicine, and improve your clinical skills, make sure to register for a free trial account, which will give you access to free videos and downloads. We’ll help you make the right decisions for yourself and your patients.
- Aboyans, V, Criqui, MH, Abraham, P, et al. 2012. Measurement and interpretation of the ankle-brachial index: a scientific statement from the American Heart Association. Circulation. 126: 2890–2909. PMID: 23159553
- Cervin, A, Wanhainen, A, and Björck, M. 2020. Popliteal aneurysms are common among men with screening detected abdominal aortic aneurysms, and prevalence correlates with the diameters of the common iliac arteries. Eur J Vasc Endovasc Surg. 59: 67–72. PMID: 31757587
- Cleveland Clinic. 2021. Leg and foot ulcers. Cleveland Clinic. https://my.clevelandclinic.org
- Cleveland Clinic. 2021. Marfan syndrome. Cleveland Clinic. https://my.clevelandclinic.org
- Cleveland Clinic. 2021. Popliteal artery entrapment syndrome (PAES). Cleveland Clinic. https://my.clevelandclinic.org
- Cleveland Clinic. 2021. Statin medications & heart disease. Cleveland Clinic. https://my.clevelandclinic.org
- Collins, L and Seraj, S. 2010. Diagnosis and treatment of venous ulcers. Am Fam Physician. 81: 989–996. PMID: 20387775
- Høyer, C, Sandermann, J, and Peterson, LJ. 2013. The toe-brachial index in the diagnosis of peripheral arterial disease. J Vasc Surg. 58: 231–238. PMID: 23688630
- Jaoude, WA. 2010. Management of popliteal artery aneurysms. SUNY Downstate Department of Surgery. http://www.downstatesurgery.org
- Johns Hopkins Medicine. 2021. Aneurysm. Johns Hopkins Medicine. https://www.hopkinsmedicine.org
- Kassem, MM and Gonzalez, L. 2020. “Popliteal artery aneurysm”. In: StatPearls [Internet]. Treasure Island (FL): StatPearls Publishing. https://www.ncbi.nlm.nih.gov
- Moxon, JV, Parr, A, Emeto, TI, et al. 2010. Diagnosis and monitoring of abdominal aortic aneurysm: current status and future prospects. Curr Probl Cardiol. 35: 512–548. PMID: 20932435
- Richert, DL. 2016. Gundersen/Lutheran Ultrasound Department Policy and Procedure Manual. Gundersen Health System. https://www.gundersenhealth.org
- Rivera, PA and Dattilo, JB. 2020. “Pseudoaneurysm”. In: StatPearls [Internet]. Treasure Island (FL): StatPearls Publishing. https://www.ncbi.nlm.nih.gov
- Stanford Medicine 25. 2021. Measuring and understanding the ankle brachial index (ABI). Stanford Medicine 25. https://stanfordmedicine25.stanford.edu/
- Teo, KK. 2019. Acute peripheral arterial occlusion. Merck Manuals Professional Edition. https://www.merckmanuals.com
- The Regents of the University of California. 2020. Diabetic foot ulcers. UCSF Department of Surgery. https://surgery.ucsf.edu
- Zwiebel, WJ and Pellerito, JS. 2005. Introduction to Vascular Ultrasonography. 5th edition. Philadelphia: Elsevier Saunders. (Zwiebel and Pellerito 2005, 254–259)