Synopsis
Link foregut, midgut and hindgut territories to arterial, venous, lymphatic and autonomic routes, then apply those maps to visceral relations and collateral pathways.
- The coeliac trunk supplies foregut-derived organs through left gastric, splenic and common hepatic branches; the superior mesenteric artery supplies midgut and the inferior mesenteric artery hindgut.
- Watershed labels describe border territories between arterial systems, but actual perfusion depends on arcades, marginal vessels, pressure and anatomical variation.
- Portal venous blood from abdominal gut and spleen passes to liver before systemic return; the portal vein forms behind the pancreatic neck from superior mesenteric and splenic veins.
Reasoning priorities
Assign a supplied gut segment to the most likely unpaired arterial system.
Use embryological boundary and named branch, then check overlap and anastomoses instead of treating the border as a sharp avascular line.
Worked reasoning
A supplied angiographic diagram shows reduced flow in a vessel arising anteriorly from the aorta at L1 and passing behind the pancreatic neck before crossing the third duodenal part; affected bowel extends from distal duodenum to proximal transverse colon.
- Use the aortic level and retro-pancreatic origin to identify the superior mesenteric artery rather than the coeliac trunk or IMA.
- Check the supplied bowel range against midgut derivatives: distal duodenum, jejunum, ileum, caecum, ascending colon and proximal transverse colon.
- Relate the vessel to the superior mesenteric vein on its right and to the pancreatic/duodenal structures that overlie or underlie its course.
- Conclude that the diagram represents an SMA/midgut territory; do not infer the cause or reversibility of reduced flow from anatomy alone.
- Verify by tracing jejunal/ileal and colic branches and checking whether collateral pathways shown are truly connected and patent.