Anatomia Venosa

ProSono

copyright 2006

Lower Extremity
Venous Anatomy
Over many years, as clinical medicine caught up with classic academic
anatomy, the veins of the leg acquired various names creating confusion and
miscommunication. In the last several years, attempts have been made to
standardize anatomical terminology of the leg veins. In 2004, the International
Union of Phlebology andInternational Federation of Anatomical Association
(IFAA) elaborated a revision of the venous nomenclature in the leg.1 The names
and descriptions adopted by the IFAA are used throughout this study.

General Anatomic Considerations
Superficial veins are large, relatively thick-walled, muscular structures that
lie just under the skin within the subcutaneous fascial layer. In the extremities
they form acomplex network of collecting veins that gather blood from the skin
and superficial fascia, passively directing it into the deep system through truncal
or perforating veins (see below). Among the superficial veins are the great and
small saphenous veins of the leg, the cephalic and basilic veins of the arm,
and the external jugular veins of the neck. The deep veins, on the other hand,
arethin-walled and less muscular and lie within the deep fascia usually in close
proximity to a bone. Deep veins accompany arteries (often as venae comitantes)
and bear the same names as the arteries that they parallel. The cross-sectional
area of these veins is roughly three times that of the adjacent artery.
Within the skeletal muscles are large, thin-walled veins that sometimes are
referred toas sinusoids. As part of the “bellows” of the muscle pump
mechanism, they serve a particularly important function during exercise. In the
calf, the soleal sinusoids empty into the posterior tibial vein, and the
gastrocnemius sinusoids usually drain directly into the popliteal vein.
In addition to the deep and superficial systems in the both the upper and
lower extremities, communicating veinsconnect the deep and superficial
systems. These short, thick-walled veins perforate through the fascia and
connect the two systems in series.
Also called perforators, these
communicating veins allow for collateralization when normal flow channels are
obstructed but they also contain valves that prevent blood in the higher-pressure
deep system from refluxing back into the lower pressuresuperficial system. In
the leg, congenital absence or damage of these valves results in abnormally
Lower Extremity Venous Anatomy

(1)

ProSono

copyright 2006

elevated pressure in the superficial veins which can cause or contribute to the
formation of varicose veins and other sequelae associated with chronic venous
insufficiency.
One of the most important anatomic feature
Table I.Valve Distribution in the
of veins, from a clinical perspective, is the
Deep System of the Leg
presence of venous valves. Each of these
(approximate numbers)
delicate, but extremely strong, bicuspid strucSuperficial femoral vein
3
tures lies at the base of a segment of vein that is
2-4
expanded into a venous sinus.
This Popliteal vein
arrangement permits the valves to open widely Anteriortibial veins
9 -11
without coming into contact with the wall, thus
9 -19
permitting rapid closure when flow begins to Posterior tibial veins
Peroneal veins
7
reverse.
There are approximately 9 to 11 valves in the
anterior tibial vein, 9 to 19 in the posterior tibial, 7 in the peroneal, 1 in the
popliteal, and 3 in the superficial femoral vein. In two-thirds of the femoral veins
a valveis present at the upper end within 1 cm of the inguinal ligament. About
one-quarter of the external iliac veins have a valve. The common iliac vein
usually has no valves. Superficial veins have fewer valves - approximately seven
to nine in the greater and lesser saphenous veins. Fifty-six valves are present in
venules as small as 0.15 mm in diameter.
Table I summarizes valve distribution...