During normal intestinal rotation, the midgut rotates around the superior mesenteric artery (SMA) by how many degrees in a counterclockwise direction?

Explanation

## Midgut Rotation Mechanics **Key Point:** The midgut rotates 270 degrees (or 3/4 of a full turn) counterclockwise around the SMA as its axis during weeks 6–10 of gestation. ### Rotation Phases 1. **First 90 degrees** — Duodenum moves posteriorly; jejunum swings to the left 2. **Second 90 degrees** — Jejunum moves inferiorly; ileum swings to the right 3. **Third 90 degrees** — Colon moves superiorly and anteriorly to the right upper quadrant **High-Yield:** After 270° rotation, the final anatomical positions are: - Duodenum: retroperitoneal, C-shaped, posterior - Jejunum: left abdomen, intraperitoneal - Ileum: right lower quadrant, intraperitoneal - Colon: right side of abdomen (ascending colon) **Mnemonic:** **270 = Three-quarters turn** — remember "three" (270°) as the key number for midgut rotation. ### Clinical Significance Abnormal rotation (incomplete or reversed) leads to **malrotation**, which predisposes to **volvulus** and intestinal obstruction, particularly in infants. [cite:Langman's Embryology Ch 13]