Page 806 - Fundamentals of anatomy physiology

The largest, the superior sagittal sinus, is in the falx cerebri
(Figure 14–3, p. 492). Most of the inferior cerebral veins converge
within the brain to form the great cerebral vein. It delivers
blood from the interior of the cerebral hemispheres and the
choroid plexus to the straight sinus. Other cerebral veins
drain into the cavernous sinus with numerous small veins
from the orbit. Blood from the cavernous sinus reaches the
internal jugular vein through the petrosal sinuses.
The venous sinuses converge within the dura mater in the
region of the lambdoid suture. The left and right transverse
sinuses begin at the confluence of the occipital, sagittal, and
straight sinuses. Each transverse sinus drains into a sigmoid
sinus, which penetrates the jugular foramen and leaves the
skull as the internal jugular vein. It descends parallel to the
common carotid artery in the neck. p. 783
Vertebral veins drain the cervical spinal cord and the
posterior surface of the skull. These vessels descend within the
transverse foramina of the cervical vertebrae, along with the ver-
tebral arteries. The vertebral veins empty into the brachiocephalic over the right side of the vertebral column to enter the tho-
veins of the chest (discussed later in the chapter).
Superficial Veins of the Head and Neck. The superficial veins of
the head converge to form the temporal, facial, and maxillary
veins (Figure 21–27c). The temporal vein and the maxillary
vein drain into the external jugular vein. The facial vein
drains into the internal jugular vein. A broad anastomosis be-
tween the external and internal jugular veins at the angle of the
mandible provides dual venous drainage of the face, scalp, and
cranium. The external jugular vein descends toward the chest
just deep to the skin on the anterior surface of the sternoclei-
domastoid muscle. Posterior to the clavicle, the external jugular
vein empties into the subclavian vein. In healthy individuals, the
external jugular vein is easily palpable. A jugular venous pulse
(JVP) is sometimes detectable at the base of the neck.
Venous Return from the Upper Limbs. The digital veins
empty into the superficial and deep palmar veins of the
hand, which interconnect to form the palmar venous arches
(Figure 21–28). The superficial arch empties into the cephalic
vein, which ascends along the radial side of the forearm; the
median antebrachial vein; and the basilic vein, which as-
cends on the ulnar side. Anterior to the elbow is the superficial
median cubital vein, which passes from the cephalic vein,
medially and at an oblique angle, to connect to the basilic vein.
(Venous blood samples are typically collected from the median
cubital.) From the elbow, the basilic vein passes superiorly
along the medial surface of the biceps brachii muscle.
The deep palmar veins drain into the radial vein and
the ulnar vein. These veins fuse to form the brachial vein,
running parallel to the brachial artery. As the brachial vein
continues toward the trunk, it merges with the basilic vein and
becomes the axillary vein, which enters the axilla.
Chapter 21 Blood Vessels and Circulation 793
Formation of the Superior Vena Cava. The cephalic vein joins
the axillary vein on the lateral surface of the first rib, form-
ing the subclavian vein, which continues into the chest. The
subclavian vein passes superior to the first rib and along the
superior margin of the clavicle. It merges with the external
and internal jugular veins of that side. This fusion creates the
brachiocephalic vein, or innominate vein, which penetrates the
body wall and enters the thoracic cavity.
Each brachiocephalic vein receives blood from the verte-
bral vein of the same side, which drains the back of the skull
and spinal cord. Near the heart, at the level of the first and
second ribs, the left and right brachiocephalic veins join, cre-
ating the superior vena cava. Close to the point of fusion, the
internal thoracic vein empties into the brachiocephalic vein.
The azygos (AZ-ı.-gos) vein is the major branch of the
superior vena cava. This vein ascends from the lumbar region
racic cavity through the diaphragm. The azygos vein joins the
superior vena cava at the level of vertebra T2. On the left side,
the azygos receives blood from the smaller hemiazygos vein,
which in many people also drains into the left brachiocephalic
vein through the highest intercostal vein.
The azygos and hemiazygos veins are the chief collecting
vessels of the thorax. They receive blood from (1) intercostal
veins, which in turn receive blood from the chest muscles;
(2) esophageal veins, which drain blood from the inferior
portion of the esophagus; and (3) smaller veins draining other
mediastinal structures.
21Figure 21–29 diagrams the venous branches of the superior
vena cava.
The Inferior Vena Cava
The inferior vena cava (IVC) collects most of the venous blood
from organs inferior to the diaphragm. (A small amount reaches
the superior vena cava by the azygos and hemiazygos veins.)
Veins Draining the Lower Limbs. Blood leaving capillaries in
the sole of each foot collects into a network of plantar veins,
which supply the plantar venous arch (Figure 21–30a). The
plantar network sends blood to the deep veins of the leg: the
anterior tibial vein, the posterior tibial vein, and the fibular
vein. The dorsal venous arch collects blood from capillaries
on the superior surface of the foot and the digital veins of the
toes. The plantar arch and the dorsal arch are extensively in-
terconnected, and the path of blood flow can easily shift from
superficial to deep veins.
The dorsal venous arch is drained by two superficial veins:
the great saphenous (sa-FE. -nus; saphenes, prominent) vein
and the small saphenous vein. The great saphenous vein
ascends along the medial aspect of the leg and thigh, draining
into the femoral vein near the hip joint. The small saphenous