Vessels and nerves of the hand
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Transcript
All hands on deck everyone!
We’re taking a deep dive into the blood supply and nerves of the most mobile and dexterous parts of our musculoskeletal system, the hands.
Human hands are supplied by an intricate network of blood vessels and nerves, which all work hand-in-hand to deliver the necessary blood supply and coordination in order for the hand muscles to be able to type, draw, suture, climb and everything else hands do.
The hand’s blood supply comes entirely from two main sources: the ulnar and radial arteries, which both originate from the brachial artery.
Inside the hand, the radial and the ulnar arteries give off numerous branches and anastomoses, ensuring that working muscles get an uninterrupted blood supply throughout our versatility of movements.
Both the ulnar and the radial arteries enter the hand from the wrist.
The ulnar artery travels down the medial forearm and enters the hand medally, while the radial artery runs down the lateral forearm and enters the hand laterally.
Let’s look at the ulnar artery first.
When entering the wrist, the ulnar artery passes superficiall to the transverse carpal ligament, also known as the flexor retinaculum, and enters the hand through a small tunnel called the ulnar canal, or Guyon’s canal.
The ulnar canal has a roof, made up by the thickened superficial palmar fascia, a floor made up by the transverse carpal ligament, a medial wall, consisting of the pisiform and pisohamate ligament, and a lateral wall made up by the hook of the hamate.
The ulnar canal also allows the ulnar nerve to pass through, medial to the ulnar artery.
After the ulnar artery reaches the hand, it divides into superficial palmar arch and a deep palmar branch.
The superficial palmar arch is the main termination of the ulnar artery and starting in the medial part of the hand it courses towards the lateral part of the hand to anastomose with the superficial branch of the radial artery.
Along its course, the superficial palmar arch gives rise to three branches known as the common palmar digital arteries.
Each of these divides into a pair of proper palmar digital arteries, which run along the sides of the 2nd to 5th digits.
Resumen
The arterial blood supply to the hand mainly comes from the radial and the ulnar artery. Within the hand, both the ulnar and radial arteries divide into branches that anastomose into superficial palmar arch and deep palmar branches. The superficial palmar arch gives three branches called the common palmar digital arteries, whereas the deep palmar arch gives off the princeps pollicis artery to supply the thumb, the radialis indicis artery to supply the index finger, and the three palmar metacarpal arteries to supply their other digits.
The hand has superficial and deep veins. On the dorsal side, the superficial veins form the dorsal venous network which drain into dorsal metacarpal veins in the hand, contributing to two major veins in the forearm: the cephalic vein on the lateral side, and the basilic vein that runs medially. On its palmar side, the hand has superficial and deep palmar venous palmar arches, which drain into the deep veins of the forearm.
Finally, the hand is innervated by three main nerves, which are the median, ulnar and radial nerves. The median nerve innervates some of the thenar muscles, the lateral lumbricals, and provides the sensation to the palm, and the distal parts of the lateral 3 and part of the fourth digits. The ulnar nerve innervates most of the intrinsic hand muscles, and provides the sensory innervation to the dorsal and palmar surfaces of the fifth and part of the fourth digits. Finally, the radial nerve does not innervate any muscle in the hand. It provides sensory innervation to the skin of the lateral half of the dorsal part of the hand and thumb. It also innervates the proximal parts of the second, third, and half of the fourth digits, on their dorsal side.
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