The vena cava is the largest venous duct of the
organism. Its role is to channel the de-oxygenated blood, effluent from organs
and tissues, into the right atrium of the heart pump. It is also the largest
blood vessel. The vena cava is actually distinct in two vessels, the superior
vena cava and the inferior vena cava, both draining in the right atrium, but
different both on the morphological and embryological level.
The upper cavity drains the upper territory: upper limbs, neck and head and
directs blood forward and down and medially, into the right ventricle. It forms
in the thorax due to the confluence of two large collecting veins, the right and
left brachiocephalic venous trunks, each of which derives from the union of v.
internal jugular that collects the waste blood from the head and from the deep
regions of the neck with the subclavian vein that collects the waste blood from
the upper limb, from the superficial regions of the head and neck and from the
upper part of the thorax. The superior vena cava receives the azigos vein in the
mediastinum.
It has an extrapericardic course in
which it is in relation to the phrenic nerve, anteriorly with the pleura and the
right lung, anteriorly with the thymus, medially with the arch of the aorta,
behind with the right main bronchus and with the lymph nodes and the vagus nerve
right.
The inferior cava drains the thorax, abdomen, pelvis and lower limbs. It also transports the absorbed nutrients to the enteric level. The inferior vena cava forms on the right side of the 4 lumbar vertebra from the union of the two large common iliac veins that originate from the confluence of the internal and external iliac veins. Internal iliac veins collect blood from the pelvis and pelvic organs it contains; the iliac veins outside the blood draining from the lower limb. The lower vvava goes up along the right vertebral column and passes through the diaphragm into the right atrium; in its course it receives the blood that flows from the lumbar, frenum, lumbar, parietal veins and from the gonads, kidneys and adrenals.
The portal vein is the venous trunk that leads to the liver the waste blood
of the intestine, from the spleen, from the pancreas, from the gall bladder. It
branches off and becomes capillarized in the hepatic parenchyma where it
originates the wonderful network of lobules from which the wonderful venous
network of lobules originates. The trunk of the portal vein is formed behind the
head of the pancreas, from the confluence of the superior and inferior
mesenteric veins and the lenial vein; then the trunk is raised upwards, medially
and to the right until it reaches the hepatic hilus where it divides into the
right and left portal portals; the left vapical, right gastric, cystic veins and
umbilical veins flow into the portal system. The portal vein is related to the
aorta which leaves medially, behind with the cavity, laterally with the
coledochus, forward with the head of the pancreas and with the first portion of
the duodenum.
Superior mesenteric vein, collects blood from the small intestine, right
half of the large intestine and from the stomach, pancreas, and large omentum.
Veins flow: right colic, ileocolica, middle colic, pancreatic-duodenal vein,
pancreatic veins, duodenal veins, gastroepiploic vein.
Inferior mesenteric vein, collects waste blood from the left half of the
large intestine. It originates from the rectum as a confluence of the superior
rectal vein which is anastomosed with the middle and lower rectal veins, both
tributaries of the internal iliac vein and then of the inferior cavity system.
it ends in acute joining with the acute angle of the vein.
Lienal vein collects the waste blood from the spleen, from the pancreas,
from the stomach and from the big omentum. it ends its journey by joining the
superior mesenteric vein.