Certified Clinical Transplant Nurse (CCTN) Practice Exam

The portal vein is formed at the junction of the superior mesenteric vein and the splenic vein, which is located near the neck of the pancreas. This anatomical relationship is crucial for understanding the venous drainage of the abdominal organs, particularly the gastrointestinal tract and spleen, and how blood flows into the liver for processing.

The superior mesenteric vein collects blood from the small intestine and part of the colon, while the splenic vein drains blood from the spleen. Their convergence at the neck of the pancreas to form the portal vein is an important anatomical landmark. This formation allows the portal vein to carry nutrient-rich blood from the digestive organs to the liver, where it is processed and detoxified, thus playing a critical role in maintaining overall metabolic homeostasis.

In contrast, the other options do not accurately represent the anatomical significance of the portal vein's formation. It is not formed behind the liver or at the entrance of the diaphragm, as these locations are not relevant to its anatomical origin and function. Additionally, while the inferior vena cava is a vital component of venous return in the abdomen, it is unrelated to the formation of the portal vein. Understanding this anatomy is essential for clinical practices in transplantation and hepatobiliary medicine.