Which vein accompanies the descending aorta?

The inferior vena cava is the correct answer because it runs parallel to the descending aorta and is responsible for draining deoxygenated blood from the lower body back to the heart. It collects blood from the lower extremities, pelvis, and abdomen and transports it to the right atrium of the heart. Positionally, the inferior vena cava is situated to the right of the descending aorta. This anatomical relationship is critical for understanding circulation and the organization of the body's vascular system.

In contrast, the superior vena cava collects blood from the upper body and pours it into the right atrium, but it is situated above the level of the aorta rather than accompanying it. The axillary vein drains blood from the upper limb and is not in close proximity to the descending aorta. Similarly, the jugular vein, which drains blood from the head and neck, runs vertically alongside the cervical spine, far removed from the thoracic structure of the descending aorta. Thus, the inferior vena cava's position and function make it the correct answer to the question about which vein accompanies the descending aorta.