600
UNIT FOUR
the venous system are difF cult to follow. This is because the
vessels commonly connect in irregular networks, so many
unnamed tributaries may join to form a large vein. On the
other hand, larger veins typically parallel the courses of named
arteries, and these veins often have the same names as their
counterparts in the arterial system. ┬▒or example, the renal vein
parallels the renal artery, and the common iliac vein accompa-
nies the common iliac artery.
The veins that carry the blood from the lungs and myo-
cardium back to the heart have already been described. The
15.8
VENOUS SYSTEM
Venous circulation returns blood to the heart after gases,
nutrients, and wastes are exchanged between the blood and
body cells.
Characteristics of Venous Pathways
The vessels of the venous system originate with the merging
of capillaries into venules, venules into small veins, and small
veins into larger ones. Unlike the arterial pathways, those of
Superficial circumflex
iliac a.
Right common
iliac a.
Deep circumflex
iliac a.
External iliac a.
Deep femoral a.
Lateral femoral a.
Abdominal
aorta
Internal
iliac a.
Superficial
pudendal a.
Femoral a.
Deep genicular a.
Anterior tibial a.
Posterior tibial a.
Dorsalis pedis a.
Medial plantar a.
Anterior view
Posterior view
Lateral plantar a.
Fibular a.
Popliteal a.
FIGURE 15.50
Major branches of the external iliac artery. (
a.
stands for artery.)
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