Objectives

1. To define the vertebral level of origin, course and branches of distribution of the celiac trunk, superior mesenteric and inferior mesenteric
2. To describe the pattern of blood supply to the small and large intestines, especially the formation of arcades, and the marginal artery
3. To describe the pattern of blood supply including venous drainage of the various organs of the gastro-intestinal tract and relate this to the embryonic origin.
4. To localise the various lymph node groups in the abdomen, and understand which organs they drain
5. To outline the distribution of the vagus and splanchnic nerves; and sacral parasympathetic outflow to the organs of the gastro-intestinal tract.

The organs of the GIT receive arterial blood supply from three arteries:

• Coeliac trunk for foregut
• Superior mesenteric artery for midgut
• Inferior mesenteric artery for hindgut

The veins drain into the portal vein and from thence to the liver and ultimately inferior vena cava.

Lymph drains into local mesenteric nodes, then para-aortic nodes then to the thoracic duct.

The vagus nerve supplies parasympathetic innervation upto the proximal 2/3rd of the transverse colon where it hands over to the sacral outflow. Sympathetic innervation is derived from the greater, lesser and least splanchnic nerves (T6-T12). Sensory fibres run with the sympathetic.