9 © Springer International Publishing AG, part of Springer Nature 2018 P. Zamboni et al. (eds.), Saphenous Vein-Sparing Strategies in Chronic Venous Disease, https://doi.org/10.1007/978-3-319-70638-2_2 Functional Anatomy of Leg Veins Sergio Gianesini, Paolo Zamboni, and Erika Mendoza 2.1 Introduction Lower limb venous anatomy knowledge is not necessary just for getting oriented inside the drainage routes. Rather it is fundamental for a proper comprehension of the architecture which infuences haemodynamics law application. Communicating vessel principle, Venturi’s effect and Poiseuille law are just some of the many fundamentals in venous return determi- nants, all infuenced by anatomy parameters like valve density, vessel calibre and length. Moreover, the anatomical relationship among veins and muscle masses strictly infuences the systolic push effect on the same vessels, so deter- mining a velocity and pressure gradient moving from the most superfcial towards the deepest compartments. In conclusion, lower limb venous anatomy knowledge is necessary since itself is a determi- nant of the venous return pathophysiology. Anatomy of leg veins is complex and described in various textbooks, to which we refer the inter- ested reader (see Literature at the end of the chap- ter) [1–3]. In this chapter, the focus lays on those information concerning deep and superfcial veins which are relevant to the non-ablating treatment of the saphenous veins. A detailed anatomical information necessary for the superfcial vein exploration is included in Chap. 4, Ultrasound. The venous system has been classically divided into two distinct parts. On the one hand, we fnd the superfcial system which courses superfcially to the muscular fascia and is respon- sible for carrying the blood away from the subcu- taneous tissue and, on the other hand, the deep or subfascial system which is responsible for drain- ing the muscles and bones. These two systems are separated anatomically by the muscle fascia. Both systems are connected by perforating veins. Since the upcoming of duplex ultrasound devices and the new investigation possibilities of leg veins, the anatomical division of superfcial leg veins into saphenous veins running between the muscular fascia and the saphenous fascia and epifascial veins was rediscovered [4]. Franceschi frst described three different networks: “N1” for the deep veins, “N2” for the interfascial veins (saphenous veins) and “N3” for the epifascial veins [5]. Zamboni described the saphenous compartment in 1997 [6, 7], and Caggiati and S. Gianesini, M.D., Ph.D. (*) Vascular Diseases Center, University of Ferrara, Ferrara, Italy USUHS University, Bethesda, MD, USA P. Zamboni, M.D. School of Vascular Surgery and Vascular Diseases Center, University of Ferrara, Ferrara, Italy Unit of Translational Surgery, AOU Ferrara, Ferrara, Italy e-mail: zmp@unife.it E. Mendoza, M.D., Ph.D. Venenpraxis, Wunstorf, Germany e-mail: erika.mendoza@t-online.de 2