The deep palmar arch is one of the arterial networks found in the hand. The arch splits off of the radial artery, and then loops and meets with the deep palmar branch of the ulnar artery. During its course, the arch runs over the metacarpal bones. It is partially covered by the adductor pollicis' oblique head. The finger's flexor tendons and the lumbricals of the hand also cover the arch. Also, the arch branches into the palmar metacarpal arteries, which serve the fingers but not the thumb. The princeps pollicis artery serves the thumb. All of these arterial vessels convey oxygenated blood from the lungs and heart. The deep palmar arch and its corresponding branches have venous counterparts of similar names. Veins always work opposite of arteries, carrying oxygen-depleted blood back to the heart and lungs. The deep palmar arch should not be confused with the superficial palmar arch, which also connects the radial and ulnar arteries. Like its deeper counterpart, the superficial palmar arch branches out into smaller arteries that serve the fingers.