SMA injuries, Fullen zone classification, and their associated bowel segments1 27
| Zone | Segment SMA | Ischemic risk | Bowel affected |
|---|---|---|---|
| I | Trunk proximal to 1st branch | Maximal | Jejunum, ileum, right colon |
| II | Trunk between inferior pancreaticoduodenal and middle colic | Moderate | Major segment, small bowel, right colon |
| III | Trunk distal to middle colic | Minimal | Minor segment or segments, small bowel or right colon |
| IV | Segmental branches (jejunal, ileal, colic) | None | None |
SMA, superior mesenteric artery.