Arteries, Veins, Lymphatics #

Arterial Supply #

The arterial supply of the stomach is derived from all three branches of the coeliac artery, which arises from the front of the aorta between the crura of the diaphragm (Last l984). It is a short wide trunk, surrounded by the coeliac lymph nodes and flanked by the coeliac ganglia of the sympathetic system.

The first branch, the left gastric artery, runs to the left, giving off an ascending oesophageal branch, and supplying the upper part of the stomach; it may also give rise to the left hepatic artery (Moore l980). It then turns downwards between the two layers of the lesser omentum, running to the right along the lesser curvature. It divides into two parallel branches, which give off branches to the anterior and posterior gastric walls and which anastomose freely with arteries from the greater curvature. The two branches of the left gastic artery then anastomose with the two branches of the right gastric artery in the region of the incisura angularis.

The second branch of the coeliac trunk, the hepatic artery, passes downwards as far as the first part of the duodenum. It then turns forwards at the opening into the lesser sac (epiploic foramen) and curves upwards into the space between the two layers of the lesser omentum towards the porta hepatis, to supply the liver. As it turns into the lesser omentum the hepatic artery gives off the gastro-duodenal and right gastric arteries. The latter passes to the left between the two layers of the lesser omentum, along the lesser curvature of the stomach, dividing into two branches which anastomose with the branches of the left gastric artery. The right gastric artery also gives off branches to the anterior and posterior gastric walls, anastomosing with branches from the right gastro- epiploic artery.

The gastro-duodenal artery passes downwards behind the first part of the duodenum, which it supplies by multiple small branches; it then divides into the superior pancreatico-duodenal artery, supplying the second part of the duodenum and head of the pancreas, and the right gastro-epiploic artery. The latter turns to the left, passes along the greater curvature of the stomach between the layers of the greater omentum, giving off branches to the anterior and posterior gastric walls. It anastomoses with the left gastro- epiploic artery at about the midportion of the greater curvature (Menguy l976).

The third branch of the coeliac trunk, the splenic artery, passes to the left along the upper border of the pancreas, behind the peritoneum and the stomach, to supply the spleen. During its course it gives off branches to the pancreas; just before entering the splenic hilum it gives off the short gastric arteries supplying the gastric fornix, and the left gastro-epiploic artery. The latter passes downwards and to the right along the greater curvature of the stomach, between the two layers of the greater omentum, to anastomose with the right gastro-epiploic artery at the midportion of the greater curvature. It gives off branches to the anterior and posterior gastric walls, which anastomose with branches of the gastric arteries along the lesser curvature. Other branches, the epiploic arteries, pass downwards between the layers of the greater omentum.

Branches from the arterial arcades on the lesser and greater curvatures ramify through the submucosa, forming a rich arterial network from which branches arise to supply the mucus membrane. Because of this arrangement the mucosa is not supplied by end arteries, with the possible exception of the mucosa along the lesser curvature, which appears to receive its arterial supply directly from branches of the right and left gastric arteries (Menguy l976).

The first 2 cm of the duodenum is supplied by multiple small branches from the hepatic and gastroduodenal arteries (Last l984). According to Cunningham (l947) the first part of the duodenum occupies the frontier zone between the coeliac and superior mesenteric vascular supplies, and the vessels which supply it vary considerably in their size and mode of origin; the peculiarity of its blood supply may partly account for the frequency with which it is the seat of ulceration.

Venous Drainage #

The position of the gastric veins is similar to that of the arteries along the lesser and greater curvatures. All the gastric veins drain either directly or indirectly into the portal system, which carries venous blood to the liver.

The left gastric vein runs to the left along the lesser curvature, receiving the oesophageal veins below the oesophageal hiatus in the diaphragm. Usually it drains directly into the portal vein at the superior border of the pancreas.

The right gastric vein runs along the lesser curvature to the right, towards the pylorus, joining the portal vein behind the first part of the duodenum. It receives the prepyloric vein, a small vein running vertically across the anterior surface of the gastro-duodenal junction on the pyloric ring; it is an important visual guide to the situation of the ring (Chap. 3).

The left gastro-epiploic vein, running to the left along the greater curvature, and the short gastric veins, drain into the splenic vein or its tributaries. Having received tributaries from the pancreas as well as the inferior mesenteric vein, the splenic ultimately joins the superior mesenteric vein to form the portal vein.

The right gastro-epiploic vein runs to the right as far as the head of the pancreas. Usually it turns downwards to join the superior mesenteric vein, draining into the portal vein. Considerable variations may occur and the right gastro-epiploic may enter the portal vein directly, or it may join the splenic vein. There is no gastroduodenal vein.

The veins from the first 2 cm of the duodenum drain into the prepyloric vein (Last l984).

Lymphatic Drainage #

In a meticulous study of 30 post-mortem specimens, Jamieson and Dobson (l907) found that the lymph vessels in the walls of the stomach arise in the subepithelial interglandular tissue of the mucosa, from where they pass outwards between the glands to communicate with each other in the peri-glandular plexus. Vessels proceed from here into the subglandular plexus between the glands and muscularis mucosae. Short vessels then pierce the muscularis mucosae to break up on its outer surface to form the submucous plexus. Large vessels draining this plexus pass outwards through the muscular coats, communicating with the networks among the muscle fibres, and open into the subserous plexus. From the latter valved collecting vessels radiate to the curvatures of the stomach to enter the omenta. By means of injection techniques it was shown that fluid passed from the submucous to the subserous plexus, but not in the reverse direction.

Doubt had been expressed by previous authors as to the continuity of the gastric and duodenal plexuses. Jamieson and Dobson (l907) found that injection of the gastric submucous plexus showed free communication with the submucous plexus of the duodenum. Injection of the gastric subserous plexus showed a sharp demarcation at the pyloric ring, with the fluid flowing in the direction of the gastric curvatures. In only one specimen could direct communication between the gastric and duodenal subserous plexuses be demonstrated. However, many of the collecting vessels from the pyloric subserous network ran downwards over the duodenum to reach the subpyloric glands, and as they received vessels from the duodenum it was surmized that an indirect communication was formed in this way.

Horton (l928) on the other hand, demonstrated by means of injections of India ink that an almost complete block existed between the submucous lymphatics of the stomach and those of the duodenum at the pylorus. In contrast, the subserous lymphatics of the pyloric region were continuous with those of the duodenum.

Coller et al. (l94l) divided the lymphatics of the stomach into intramural, intermediary and extramural systems. The intramural system consists of 3 networks, viz. submucosal, intermuscular and subserosal. The submucosal lymphatic channels communicate freely throughout the submucosa of the stomach and to a lesser degree with the submucosal lymphatics of the duodenum; they also communicate freely with the intermuscular and subserosal networks. The intermediary system consists of numerous small channels between the subserosal network and the extramural collecting systems. The extramural system consists of four major zones of lymphatic drainage, corresponding to the arterial supply of the stomach. Ultimately all zones drain into the coeliac nodes around the coeliac arterial trunk on the anterior aspect of the aorta.

According to Eker (l951) the stomach should be considered to have the following 4 zones of lymphatic drainage:

1. The first zone comprises the upper two-thirds of the lesser curvature and a large part of the body of the stomach. The lymphatic drainage is into the left gastric nodes lying along the left gastric artery. These nodes are joined by lymphatics coming down from the lower part of the oesophagus, and their efferents proceed to the coeliac nodes.

2. The second zone of lymphatic drainage is from the distal part of the lesser curvature, including the lesser curvature of the pyloric region, to the suprapyloric nodes along the right gastric artery. Eker (l951) stressed the fact that this zone consists of "only a small area in the lower part of the pyloric region". Efferent channels from the suprapyloric nodes drain to the hepatic and ultimately to the coeliac and aortic nodes.

3. Most of the pyloric part of the stomach as well as the right (i.e. lower) half of the greater curvature constitute the third zone. The extramural lymphatics from these areas drain into the right gastro-epiploic nodes in the gastrocolic ligament, lying along the right gastro-epiploic vessels, and into the pyloric nodes on the anterior surface of the head of the pancreas. The direction of lymph flow is from above downwards, towards the pylorus and the nodes between the head of the pancreas and second part of the duodenum. From these groups, collectively called the subpyloric glands (which also drain the first part of the duodenum), efferent vessels pass along the gastro-duodenal artery to the hepatic nodes along the hepatic artery, and thence to the coeliac nodes.

4. The fourth zone is from the left (i.e. upper) half of the greater curvature and the gastric fornix. From here lymph vessels pass to the left gastro-epiploic nodes, lying along the left gastro-epiploic artery, proceed to the pancreatico-lienal nodes along the splenic artery, and ultimately to the coeliac nodes.

Lehnert et al. (l985) studied the distribution of lymph and blood capillaries by light and transmission electron microscopy in 16 endoscopic biopsy and surgical resection specimens of human gastric mucosa and submucosa. Four were normal and 12 showed evidence of gastritis. A clear distinction between small mucosal blood and lymph capillaries was not always possible with light microscopy; a distinction could be made by electron microscopy. This showed blood capillaries at all levels of the lamina propria, and especially at its upper levels, as well as in the submucosa. Lymph capillaries on the other hand, could not be demonstrated in the upper and middle regions of the lamina propria; lymphatics were only present in the deep lamina propria adjacent to the muscularis mucosae. Larger lymph vessels were observed in the submucosa. It was concluded that the entire human gastric mucosa had a rich supply of blood capillaries, many of which were adjacent to the gastric glands and surface epithelium, but that lymphatic capillaries were present only in the deep lamina propria. It seemed if earlier descriptions, derived from light microscopy, needed revision.

Discussion #

Investigators differ on the question of continuity of gastric and duodenal lymphatics. According to Jamieson and Dobson (l907), who injected lymph plexuses in the gastric submucosa, free communication existed between gastric and duodenal submucosal lymphatics; this was also the view of Coller et al. (l941). Horton (l928, l931) and Williams (l962) on the other hand, during injections of India ink into the gastric submucosal space, found a complete block at the pylorus, with no communication between gastric and duodenal submucosal lymphatics. The differing results could be due to differences in methodology; whereas Jamieson and Dobson (l907) injected lymphatic plexuses, it seems that the injections of Horton (l928, l931) and Williams (l962) were done into the submucosal space.

According to Jamieson and Dobson (l907) the gastric and duodenal subserous lymphatics did not communicate, while Horton (l928, l931) found that they were continuous. All authors agree that the gastric submucous and gastric subserous lymphatic systems communicate freely. There is general agreement about extramural lymphatic drainage away from the stomach. These factors are of importance in the spread of gastric carcinoma, and especially when spread of pyloric carcinoma into the duodenum has to be considered (Chap. 33).

The findings of Eker (l951) show that extramural lymphatic drainage from the region of the pyloric sphincteric cylinder is downwards, to the suprapyloric and subpyloric glands.

Lehnert et al. (l985) thought that the low incidence of lymph node metastasis in early gastric carcinoma, where the lesion is confined to the mucosa, could be due to the rarity of lymph capillaries (as opposed to blood capillaries) in the mucosa.

References #

1. Coller FA, Kay EB, McIntyre RS. Regional lymphatic metastases of carcinoma of the stomach. Arch Surg l941, 43, 748-761.
2. Cunningham DJ. Text-book of Anatomy. Edit Brash JC, Jamieson EB. Oxford Univ Press, 8th ed, London l947, p 1457.
3. Eker R. Carcinomas of the stomach: investigation of the lymphatic spread from gastric carcinomas after total and partial gastrectomy. Acta Chir Scand l951, 101, 112-126.
4. Horton BT. Pyloric musculature, with special reference to pyloric block. Amer J Anat l928, 41, 197-225.
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