What vein drains the gallbladder?

The vein that specifically drains the gallbladder is the cystic vein. The cystic vein is responsible for carrying deoxygenated blood away from the gallbladder and draining it into the portal vein. This is vital because the gallbladder plays a crucial role in the storage and concentration of bile, and its proper venous drainage is essential for maintaining circulatory efficiency and liver function. Understanding the structure and function of the cystic vein is important in the context of surgeries that involve the gallbladder, such as cholecystectomy.

The other veins mentioned—middle thyroid vein, superior thyroid vein, and inferior thyroid vein—are not associated with the gallbladder at all; they are involved in draining various regions of the thyroid gland and surrounding areas. Therefore, the cystic vein stands out as the correct answer, underlining its specific role in the anatomical and physiological context of gallbladder drainage.