The midgut loop, during its physiological herniation into the umbilical cord, normally undergoes which sequence of rotations?

• A 90 degrees clockwise followed by 180 degrees anticlockwise
• B 270 degrees clockwise around the axis of the coeliac trunk
• C 270 degrees anticlockwise around the axis of the superior mesenteric artery ✓
• D 180 degrees anticlockwise followed by 90 degrees clockwise

Explanation

As the midgut loop herniates at week 6, it rotates 90 degrees anticlockwise, and after returning to the abdomen by week 10 to 12 it rotates a further 180 degrees anticlockwise, giving a total of 270 degrees anticlockwise rotation around the superior mesenteric artery axis. This brings the caecal bud to the right iliac fossa and the transverse colon in front of the duodenum. Clockwise rotation or wrong totals produce malrotation and volvulus.

Reference: Langman's Medical Embryology, 14th ed.

High-yield for: NEET PGINI-CETNExTFMGEUSMLEPLABMRCP

Written and medically reviewed by the StethoPrep medical team.