The arteries reach the gastro-intestinal trunk through the mesentery or omentum, gives off small branches to serosa and pass through the muscular coats to submucosa where they form an extensive plexus of large vessels called Heller’s plexus. From this plexus, one set of branches passes outward to supply the muscular coats and another set passes inward to the mucous membrane.
Short branches supply the muscularis mucosae, while long branches enter the lamina propria and form periglandular capillary networks. In the small intestine, each villus receives one small artery, which passes to the summit of the villus gives off a network of capillaries, which lie immediately under the epithelium. Veins correspond to the arterial branches.
The capillary network from the mucous membrane and muscular coats are drained by veins, which form a submucous venous plexus where large veins are formed. They accompany the arteries into the mesentery.
