Root of mesentery is crossed by
**Core Concept**
The root of the mesentery is a vital anatomical structure that provides attachment and support to the small intestine. It is formed by the fusion of the two layers of the peritoneum, the parietal and the visceral peritoneum, and contains the superior mesenteric vessels, among other structures.
**Why the Correct Answer is Right**
The root of the mesentery is crossed by the superior mesenteric artery and vein, which are essential for supplying blood to the small intestine. These vessels are branches of the abdominal aorta and inferior vena cava, respectively, and play a crucial role in maintaining the viability of the intestinal tissue. The crossing of these vessels at the root of the mesentery creates a potential weak point in the mesenteric attachment, which can lead to ischemia or infarction if compromised.
**Why Each Wrong Option is Incorrect**
**Option A:** The inferior mesenteric artery is not directly involved in crossing the root of the mesentery, as it primarily supplies the large intestine.
**Option B:** The splenic artery, while a branch of the celiac trunk, does not cross the root of the mesentery, and its primary role is in supplying the spleen and stomach.
**Option C:** The portal vein, although a vital structure in the abdominal cavity, does not cross the root of the mesentery; instead, it runs parallel to the superior mesenteric artery.
**Clinical Pearl / High-Yield Fact**
The root of the mesentery is a common site for vascular compromise, particularly in patients with conditions such as superior mesenteric artery syndrome or those who have undergone abdominal surgery.
**Correct Answer: B. The splenic artery.**