Abstract Objectives: To synthesise the applied clinical anatomy of gastrointestinal vascular supply with emphasis on watershed zones, circumferential perfusion patterns, and mechanisms of vascular compromise. The review aims to provide surgeons and clinicians with a practical, anatomically grounded framework for understanding perfusion vulnerability, intraoperative decision-making, and the pathophysiology of ischemic injury. Design: Narrative review integrating anatomical, surgical, radiological, and physiological literature with clinically oriented interpretation. Enhanced diagrams and comparative tables are used to support clarity and accessibility. Data Sources: Searches were conducted in PubMed, Embase, Scopus, and Google Scholar for literature relating to gastrointestinal vascular anatomy, mesenteric perfusion, watershed zones, ischemic colitis, and surgical assessment of bowel viability. Additional sources included anatomical atlases, operative textbooks, and key clinical reviews. Results: The review highlights the segmental and collateral vascular architecture of the gut, with particular focus on: • The unique vascular features of the oesophagus, stomach, duodenum, jejunum, ileum, appendix, and colon • Critical watershed zones at Griffith’s point and Sudeck’s point, where perfusion is most vulnerable • The role of circumferential blood supply and the antimesenteric border in early ischemic change • The impact of bowel distention, volvulus, and venous congestion on perfusion compromise • Practical intraoperative markers of viability and perfusion adequacy A clinically oriented synthesis is presented to support surgical planning, risk assessment, and interpretation of ischemic patterns.