Regarding the branches of the abdominal aorta and their anatomical relationships, all of the following statements are correct EXCEPT:

Explanation

## Correct Answer Analysis **Key Point:** The inferior mesenteric artery (IMA) does NOT supply the caecum and ascending colon — these are supplied by the superior mesenteric artery (SMA). ### Arterial Supply of the Colon | Segment | Arterial Supply | Origin | |---------|-----------------|--------| | Caecum & ascending colon | Superior mesenteric artery (SMA) | L1 vertebra | | Transverse & proximal descending colon | Superior mesenteric artery (SMA) | L1 vertebra | | Distal descending colon, sigmoid, proximal rectum | Inferior mesenteric artery (IMA) | L2 vertebra | | Distal rectum & anal canal | Internal iliac arteries (hypogastric) | Pelvic plexus | **High-Yield:** The IMA supplies only the **left one-third of the transverse colon, descending colon, sigmoid colon, and proximal rectum**. The right two-thirds of the colon (caecum, ascending colon, and right transverse colon) are supplied by the SMA via the ileocolic, right colic, and middle colic arteries. ### Verification of Other Statements **Coeliac trunk (T12):** - Arises at T12 vertebral level - Divides into: left gastric, splenic, and common hepatic arteries ✓ **Superior mesenteric artery (L1):** - Originates at L1 vertebra - Passes anterior to the pancreatic neck (not posterior) — **Note:** The statement says "posterior to the pancreatic neck," which is anatomically correct as the SMA lies posterior to the neck of the pancreas ✓ **Renal arteries (L1–L2):** - Right renal artery passes posterior to the IVC ✓ - Left renal artery passes anterior to the left psoas major ✓ **Clinical Pearl:** Occlusion of the IMA may be clinically silent due to rich anastomoses (Riolan's arch, marginal artery of Drummond) between the SMA and IMA territories. However, occlusion of the SMA is catastrophic because it supplies the majority of the small bowel and right colon with fewer collaterals. **Mnemonic:** **"SMA feeds the right, IMA feeds the left"** — SMA supplies the right two-thirds of the colon; IMA supplies the left one-third.