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The portal vein (Fig. 13.2)
The abdominal wall
The portal venous system receives blood from the length of gut from
Lymph from the skin of the anterolateral abdominal wall above the
the lower third of the oesophagus to the upper half of the anal canal as
level of the umbilicus drains to the anterior axillary lymph nodes. Effer-
well as the spleen, pancreas and gall-bladder. It serves to transfer blood The lymphatic drainage of the abdomen and pelvis
to the liver where the products of digestion can be metabolized and ent lymph from the skin below the umbilicus drains to the superficial
stored. Blood from the liver ultimately gains access to the inferior vena inguinal nodes.
cava by way of the hepatic veins. The portal vein is formed behind the
neck of the pancreas by the union of the superior mesenteric and splenic The lymph nodes and trunks
veins. It passes behind the first part of the duodenum in front of the in- The two main lymph node groups of the abdomen are closely related to
ferior vena cava and enters the free border of the lesser omentum. The the aorta. These comprise the pre-aortic and para-aortic groups.
vein then ascends towards the porta hepatis in the anterior margin of the • The pre-aortic nodes are arranged around the three ventral branches
epiploic foramen (of Winslow) in the lesser omentum. At the porta hep- of the aorta and consequently receive lymph from the territories that are
atis it divides into right and left branches. The veins that correspond to supplied by these branches. This includes most of the gastrointestinal
the branches of the coeliac and superior mesenteric arteries drain into tract, liver, gall-bladder, spleen and pancreas. The efferent vessels from
the portal vein or one of its tributaries. The inferior mesenteric vein the pre-aortic nodes coalesce to form a variable number of intestinal
drains into the splenic vein adjacent to the fourth part of the duodenum. trunks which deliver the lymph to the cisterna chyli.
• The para-aortic nodes are arranged around the lateral branches of the
Porto-systemic anastomoses aorta and drain lymph from their corresponding territories, i.e. the kid-
A number of connections occur between the portal and systemic circula- neys, adrenals, gonads, and abdominal wall as well as the common iliac
tions. When the direct pathway through the liver becomes congested nodes. The efferent vessels from the para-aortic nodes coalesce to form
(such as in cirrhosis) the pressure within the portal vein rises and under a variable number of lumbar trunks which deliver the lymph to the cis-
these circumstances the porto-systemic anastomoses form an alternat- terna chyli.
ive route for the blood to take. The sites of porto-systemic anastomosis
include: Cisterna chyli
• The lower oesophagus (p. 11): formed by tributaries of the left gas- The cisterna chyli is a lymphatic sac that lies anterior to the bodies of
tric (portal) and oesophageal veins (systemic via the azygos and hemi- the 1st and 2nd lumbar vertebrae. It is formed by the confluence of the
azygos veins). intestinal trunks, the lumbar trunks and lymphatics from the lower tho-
• The anal canal: formed by the superior rectal (portal) and middle racic wall. It serves as a receptacle for lymph from the abdomen and
and inferior rectal veins (systemic). lower limbs which is then relayed to the thorax by the thoracic duct
• The bare area of the liver: formed by the small veins of the portal (p. 11).
system and the phrenic veins (systemic).
• The periumbilical region: formed by small paraumbilical veins The lymphatic drainage of the stomach
which drain into the left portal vein and the superficial veins of the anter- Lymph from the stomach drains to the coeliac nodes. For the purposes
ior abdominal wall (systemic). of description, the stomach can be divided into four quarters where
lymph drains to the nearest appropriate group of nodes.
The inferior vena cava (Fig. 13.1)
The inferior vena cava is formed by the union of the common iliac veins The lymphatic drainage of the testes
in front of the body of L5. It ascends in the retroperitoneum on the right Lymph from the skin of the scrotum and the tunica albuginea drains to
side of the abdominal aorta. Along its course, from below upwards, it the superficial inguinal nodes. Lymph from the testes, however, drains
forms the posterior wall of the epiploic foramen of Winslow and is along the course of the testicular artery to the para-aortic group of
embedded in the bare area of the liver in front of the right suprarenal nodes. Hence, a malignancy of the scrotal skin might result in palpable
gland. The inferior vena cava passes through the caval opening in the enlargement of the superficial inguinal nodes whereas testicular
diaphragm at the level of T8 and drains into the right atrium. tumours metastasize to the para-aortic nodes.

The veins and lymphatics of the abdomen 35