Anatomy, Shoulder and Upper Limb, Princeps Pollicis Artery

The hand has a unique arterial blood supply. The primary source of all the blood in the hand originates from two arteries. These two arteries are the ulnar artery and the radial artery. The ulnar artery descends toward the hand to form the superficial palmar arch. The radial artery descends toward the hand and forms the deep palmar arch. The superficial palmar arch perfuses the ulnar side of the hand mainly. While the deep palmar arch will predominately perfuse the radial side of the hand, these two arches will provide collateral blood supply to each other.

These palmar arches will branch even further into digital arteries that will perfuse the digits. But the thumb does not receive blood from the digital arteries. The thumb gets a separate artery called the princeps pollicis artery. This artery is a direct branch from the deep palmar arch.

The major artery that is the source of blood for the princeps pollicis artery is the radial artery. Since the radial artery descends toward the hand to form the deep palmar arch. The princeps pollicis artery is a small muscular artery that branches from the deep palmar arch. This artery then ascends the thumb passing between two muscles. The princeps pollicis artery splits the oblique head of the adductor pollicis muscle and the first interosseous muscle. The princeps pollicis muscle ascends and terminates at the base of the proximal phalanx. At the proximal phalanx, the princeps pollicis artery terminates beneath the flexor pollicis longus muscle's tendon. Then the princeps pollicis artery will split into two smaller arteries that will further perfuse the thumb.[1]

The function of the princeps pollicis artery is to perfuse the bones, muscles, nerves, and skin in the thumb. 

During embryology, the blood vessels predominately develop from the mesodermal germ layer. The mesodermal germ layer contains mesenchymal tissue. The princeps pollicis artery develops from mesenchymal tissue. As the limbs grow during embryology, fibroblast growth factor induces the lengthening of bones, muscles, and blood vessels. Fibroblast growth factor and vascular endothelial growth factor (VEGF) have angiogenesis characteristics on blood vessels; this will induce the formation and growth of the princeps pollicis artery.

The blood supply that is provided by the princeps pollicis artery is directed towards the distal fibers of the median, radial, and ulnar nerve. The muscles that receive blood from the princeps pollicis artery are abductor pollicis brevis muscle, abductor pollicis longus muscle, extensor pollicis brevis muscle, extensor pollicis longus muscle, flexor pollicis longus muscle, flexor pollicis brevis muscle, adductor pollicis muscle,  opponens pollicis muscle, and first dorsal interosseus muscle. The skin that overlies the thumb also receives perfusion from the princeps pollicis artery.[2]

The lymphatic drainage of the thumb and the hand will drain towards the cubital fossa. At the cubital fossa, the lymph fluid will drain into the cubital lymph nodes. The lymph fluid will drain towards the axilla. Once at the axilla, the lymph fluid will enter the axillary lymph nodes. The lymph fluid eventually returns into the central circulation via the right lymphatic duct and the thoracic duct. The left thumb will drain towards the thoracic duct. While the right thumb will drain towards the right lymphatic duct.

The princeps pollicis artery provides minor blood supply to the distal nerve fibers of three nerves in the hand:

• Ulnar nerve 
• Median nerve
• radial nerve

The princeps pollicis artery's primary function is to perfuse the muscles, bone, and skin of the thumb. The blood supply sometimes overlaps with the distal nerve fibers' territory. But the princeps pollicis artery is not the dominant blood supply to the nerves in the hand.