Analysis of the Variations in the Colic Branching Pattern of the Superior Mesenteric Artery: A Cadaveric Study With Proposal to Modify Its Current Anatomical Classification

Background: Vascular anatomy of the ascending colon is more complex and variable as compared to the left. Variations range from the mode of origin, branching to territorial supply. The present study was undertaken to learn the anatomical variations of the superior mesenteric artery (SMA) and its colic branches in detail. Materials and methods: The study included 50 formalin fixed cadavers aged between 40 and 65 years. The colic branches arising from SMA were dissected to trace their mode of origin, branching pattern, and territorial supply. Based on the mode of origin of the colic branches, the SMA anatomy was classified into four patterns: I; II a, b, c; III; and IV. Results: SMA itself showed variations in its origin (as celiacomesenteric and hepatomesenteric trunk), so the colic branches arising from it. In most of the cases, middle (MCA), right (RCA), and ileocolic artery (ICA) originated independently from SMA (I). A common stem (CS) was reported between MCA and RCA (IIa) in seven cases; RCA and ICA in one (IIb); MCA and LCA in one. MCA originated from the coeliac trunk (CT) in one case. In one case, each of absent RCA (III) and accessory artery arising from SMA (IV) was also noticed. In one case, the right branch of MCA gave origin to RCA. Additionally, close association was observed between pattern IIa and incomplete inter-colic anastomosis. Conclusion: Variations in the origin of SMA may potentially influence branching patterns of colic arteries. MCA is the most variant and ICA is the most consistent branch of SMA. Distinctive variations like MCA arising from CT or arising as CS with LCA and incomplete inter-colic anastomosis in pattern IIa are of outrageous importance for operating surgeons during surgical procedures of colon. Based on study results, we propose a modification in the classification of SMA anatomy to include the CS of MCA and LCA as type IId; however, its success relies upon universal acceptance.