Page 802 - Fundamentals of anatomy physiology

travel posterior to the peritoneal lining to reach the adrenal
glands and kidneys. We consider the branches of the renal
arteries in Chapter 26.
4. The gonadal (go. -NAD-al) arteries originate between the
superior and inferior mesenteric arteries. In males, they
are called testicular arteries and are long, thin arteries that
supply blood to the testes and scrotum. In females, they
are termed ovarian arteries and supply blood to the ovaries,
uterine tubes, and uterus. The distribution of gonadal ves-
sels (both arteries and veins) differs by gender. We describe
the differences in Chapter 28.
5. Small lumbar arteries arise on the posterior surface of the
aorta. They supply the vertebrae, spinal cord, and abdomi-
nal wall.
Arteries of the Pelvis and Lower Limbs
Near the level of vertebra L4, the terminal segment of the ab-
dominal aorta divides to form a pair of elastic arteries—the
right and left common iliac (IL-e. -ak) arteries—plus the
small median sacral artery (Figure 21–23). The common iliac
arteries carry blood to the pelvis and lower limbs. They descend
posterior to the cecum and sigmoid colon along the inner
surface of the ilium. At the level of the lumbosacral joint, each
common iliac divides to form an internal iliac artery and an
external iliac artery (Figure 21–24). The internal iliac arteries
enter the pelvic cavity to supply the urinary bladder, the inter-
nal and external walls of the pelvis, the external genitalia, the
medial side of the thigh, and, in females, the uterus and vagina.
The major branches of the internal iliac artery are the gluteal, in-
ternal pudendal, obturator, and lateral sacral arteries. The external
iliac arteries supply blood to the lower limbs. They are much
larger in diameter than the internal iliac arteries.
Arteries of the Thigh and Leg. Each external iliac artery crosses
the surface of an iliopsoas muscle and penetrates the abdominal
wall midway between the anterior superior iliac spine and the
pubic symphysis on that side. It emerges on the anterior, medial
surface of the thigh as the femoral artery (Figure 21–25a,b).
Roughly 5 cm (2 in.) distal to the emergence of the femoral
artery, the deep femoral artery branches off its lateral surface.
The deep femoral artery supplies blood to the ventral and lat-
eral regions of the skin and deep muscles of the thigh. It gives
rise to the femoral circumflex arteries.
The femoral artery continues inferiorly and posterior to
the femur. As it approaches the knee, it gives rise to the descend-
ing genicular artery, which supplies the area around the knee.
At the popliteal fossa, posterior to the knee joint, the femoral
artery becomes the popliteal (pop-LIT-e. -al) artery, which then
branches to form the posterior and anterior tibial arteries.
The posterior tibial artery gives rise to the fibular artery, or
peroneal (perone, fibula) artery, and then continues inferiorly
along the posterior surface of the tibia. The anterior tibial artery
Chapter 21 Blood Vessels and Circulation 789
passes between the tibia and fibula. It emerges on the anterior
surface of the tibia. As it descends toward the foot, the anterior
tibial artery provides blood to the skin and muscles of the
anterior portion of the leg.
Arteries of the Foot. At the ankle, the anterior tibial artery
becomes the dorsalis pedis artery. It then branches re-
peatedly, supplying the ankle and dorsal portion of the foot
(Figure 21–25a,b). Figure 21–25c charts the flow of blood from
the external iliac artery to the lower limbs.
At the ankle, the posterior tibial artery divides to form the
medial and lateral plantar arteries. They supply blood to
the plantar surface of the foot. These arteries are connected to
the dorsalis pedis artery through a pair of anastomoses. The ar-
rangement produces a dorsal arch (arcuate arch) and a plantar
arch. Small arteries branching off these arches supply the distal
portions of the foot and the toes.
Systemic Veins
Veins collect blood from the tissues and organs of the body
by means of an elaborate venous network that drains into the
right atrium of the heart by the superior and inferior venae
cavae (Figure 21–26). The branching pattern of peripheral veins
is much more variable than is the branching pattern of arter-
ies. We base the discussion that follows on the most common
arrangement of veins. Complementary arteries and veins com-
monly run side by side. In many cases they have comparable
names.
21One significant difference between the arterial and venous
systems involves the distribution of major veins in the neck
and limbs. Arteries in these areas are deep beneath the skin,
protected by bones and surrounding soft tissues. In contrast,
the neck and limbs generally have two sets of peripheral veins,
one superficial and the other deep. This dual venous drainage
is important for controlling body temperature. In hot weather,
venous blood flows through superficial veins, where heat can
easily be lost. In cold weather, blood is routed to the deep veins
to minimize heat loss.
The Superior Vena Cava
All the body’s systemic veins (except the cardiac veins) ulti-
mately drain into either the superior vena cava or the inferior
vena cava. The superior vena cava (SVC) receives blood from
the tissues and organs of the head, neck, chest, shoulders, and
upper limbs.
Venous Return from the Cranium. Numerous veins drain the
cerebral hemispheres. The superficial cerebral veins and small
veins of the brain stem empty into a network of dural sinuses
(Figure 21–27a,b). These sinuses include the superior and inferior
sagittal sinuses, the petrosal sinuses, the occipital sinus, the left and
right transverse sinuses, and the straight sinus (Figure 21–27c).