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To obtain a good view of the splenic artery, it is necessary to throw the stomach upwards towards the ribs.

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FIG. 115. The stomach has been thrown upwards to show the coeliac axis and its branches; the pancreas is drawn downwards to exhibit the splenic vein. (From GRAY'S Anatomy.)

The vessel will then be seen to run along the upper border of the pancreas, which somewhat overlaps it. It is accompanied by the splenic vein, which, however lies at a lowel level, and therefore altogether behind the pancreas. The following are the branches of the splenic artery :— Pancreaticæ parvæ.

1. Pancreatic.

2. Gastric.

3. Splenic.

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Pancreatica magna.
Vasa brevia.
Left gastro-epiploic.

The arteria pancreaticæ parvæ are small twigs which come off at various points for the supply of the pancreas. The pancreatica magna is a larger branch which arises from the splenic artery near its termination. It sinks into the pancreas, and is directed from left to right in the gland substance in company with the duct of the gland.

The vasa brevia (arteriæ gastricæ breves) are five or six small arteries, of which some arise directly from the splenic, whilst others take origin from its terminal branches. They run towards the stomach between the two layers of the gastro-splenic omentum, and are distributed to the cardiac end of this viscus, anastomosing with the coronary and left gastro-epiploic arteries.

The left gastro-epiploic (arteria gastro-epiploica sinistra) takes origin from the splenic near the spleen, and is directed from left to right, along the greater curvature of the stomach, between the two anterior layers of the great omentum. It gives branches which ascend to supply both aspects of the stomach, and others which descend into the great omentum, and it ends by anastomosing with the right gastro-epiploic artery.

The splenic or terminal branches of the splenic artery reach the spleen by passing between the two layers of the lieno-renal ligament. The vasa brevia and the left gastroepiploic artery take the same route to gain the interval between the two layers of the gastro-splenic omentum.

From the above description of the branches of the coeliac axis it will be seen that the stomach is remarkably rich in

blood-vessels.

Two proceed from left to right-viz. the coronary along the lesser curvature, and the left gastroepiploic along the greater curvature; two, both branches of the hepatic, are directed from right to left-viz. the pyloric, in relation to the lesser curvature; and the right gastroepiploic, in relation to the greater curvature. The arterial circle is completed on the left by the vasa brevia, which connect the coronary artery with the left gastro-epiploic.

The Splenic Vein (vena lienalis), formed by the union of the veins which issue from the spleen, runs from left to right behind the pancreas, and at a lower level than the artery of the same name. After crossing the aorta and the root of the superior mesenteric artery, it ends by joining the superior mesenteric vein to form the vena portæ. In its course between the spleen and the vena portæ it receives the following tributaries:-(1) veins corresponding to the vasa brevia; (2) the left gastro-epiploic vein; (3) pancreatic veins; (4) the inferior mesenteric vein.

Vena Portæ.—This is a remarkable vessel. It arises after the manner of a vein, by gathering, by means of its rootlets, the blood from the capillaries of the entire abdominal portion of the alimentary canal (with the exception of the lower end of the rectum), the spleen, pancreas, and gall-bladder, whilst it ends in the liver after the manner of an artery, by pouring its blood into the hepatic capillaries. The blood which flows in the portal vein, therefore, passes through two series of capillaries before it is returned to the heart-viz. (1) the capillaries of the organs from which it is derived; (2) the hepatic capillaries.

The portal vein is formed between the neck and the head of the pancreas, by the union of the splenic and superior mesenteric veins. From this it ascends, with an inclination to the right, and ends near the right extremity of the transverse fissure of the liver by dividing into a right and left branch, one for each lobe of this organ. After emerging from under cover of the neck of the pancreas, it lies first behind the first part of the duodenum, and then between the two layers of the gastro-hepatic omentum,

close to its right free margin. In the latter situation it is placed behind the hepatic artery and the bile duct, and is accompanied by the hepatic nerves and lymphatics. The vena portæ receives the coronary, pyloric, and cystic veins. The last-named vein, however, may join its right branch.

The branches of the portal venous system are devoid of valves. This is a great predisposing cause in the production of hæmorrhoids.

Dissection. The connections of the duodenum should next be studied, and the dissector will find it advantageous in doing this to partially inflate with air both it and the stomach.

The Duodenum, or first part of the small intestine, is wider and more fixed in its position than either the jejunum or ileum. It is ten to twelve inches in length, and extends from the pylorus of the stomach to the left side of the second lumbar vertebra. Here it bends forwards on itself in the form of the duodeno-jejunal flexure and becomes continuous with the jejunum (Fig. 116). The duodenum is adapted to the front of the vertebral column, and describes a U-shaped curve around the head of the pancreas the concavity of which is directed upwards. For convenience in description it is divided into a first part, a second part, and a third part.

The first part of the duodenum (pars superior) is two inches in length, and is contained in the epigastric region. It is enveloped by the same two layers of peritoneum which invest the stomach, and consequently enjoys a limited degree of movement. Its position and relations are dependent upon the degree of distension of the stomach. When that viscus is empty, and the pylorus, in consequence, occupies the mesial plane, the first part of the duodenum passes backwards and to the right, with a slight inclination upwards, until it reaches the neck of the gall-bladder. Here it ends by bending suddenly downwards into the second part. Under these circumstances the first part of the duodenum lies in close apposition with the lobus quadratus of the liver. When the stomach, on the other hand, is distended, the pylorus comes into relation with

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the lobus quadratus, and the first part of the duodenum is pushed to the right, and occupies a depression on the under surface of the right lobe of the liver, behind and to the right of the transverse fissure. The relations of the first part of the duodenum are as follows: above, the under surface of the liver; below, the pancreas; behind, the

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common bile-duct, the gastro-duodenal artery, and the portal vein.

The second part of the duodenum (pars descendens) is usually about from three to four inches in length, and takes a downward course from the under surface of the liver. Placed at its commencement in the epigastric region, it

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