What is the main blood vessel carrying the most highly oxygenated blood in adults?

The vessel that carries the most highly oxygenated blood in adults is the pulmonary vein. This is because, after oxygenation occurs in the lungs, the pulmonary veins transport oxygen-rich blood back to the heart. Specifically, they carry this oxygenated blood from the lungs to the left atrium of the heart, where it can then be pumped out to the rest of the body.

In adults, the aorta does carry oxygenated blood from the heart to systemic circulation, but it is not the vessel with the most highly oxygenated blood, as it receives blood from the left ventricle, which may contain lower oxygen levels compared to the blood coming straight from the lungs via the pulmonary veins.

The pulmonary artery, on the other hand, carries deoxygenated blood from the right ventricle to the lungs for oxygenation, meaning it does not transport highly oxygenated blood at all.

Lastly, the coronary artery supplies blood specifically to the heart muscle itself, and while this blood is oxygenated, it still does not have the highest oxygen content compared to the blood in the pulmonary veins directly after it has been oxygenated in the lungs.