The "interfascial" veins of the lower limbs.

The veins of the lower limb are commonly divided in deep and superficial ones according to their position with respect to the Muscular Fascia (MF). Anatomical textbooks affirm that all superficial veins are thin walled vessels that run in a yielding layer of fat. Accordingly, no differences between saphenous Veins (SVs) and their tributaries (TVs) are reported by physiologists and pathophysiologists. On the contrary, the SVs do not correspond to the classic anatomic, physiologic and clinical descriptions of the "superficial" veins. In fact, the SVs: 1) are not superficial because they course between the SF and the MF; 2) they are not thin vessels, being their wall thick and rich in muscular cells; 3) they actively contribute to the complex mechanisms of venous return from the lower limbs; and finally, 4) they are quite resistant to hypertension and usually afflicted with limited varicose changes. As a consequence, the SVs should not be longer considered "real" superficial veins and the venous bed of the lower limb would be better represented by a three-layered model.