Nerves, Arteries, and Veins of the Wrist and Hand
Busy muscles need plenty of nerve supply and blood flow. Three main nerves (plus all their branches) work the wrist and hand, and many arteries and veins bring blood into and out of the hand.
The main nerves you need to know for the wrist and hand come from the median, ulnar, and radial nerves. These nerves supply the skin, muscles, joints, and other tissues. The nerves allow you to feel what your hands and fingers are touching and help you move those muscles around.
Median nerve: The median nerve enters the hand through the carpal tunnel, which is a passageway between the tubercles of the scaphoid and trapezium bones laterally and by the pisiform and the hook of the hamate on the medial side. It gives nerve supply to the thenar muscles and the first two lumbricals, plus it sends sensory fibers to the skin on the lateral part of the palm and to the sides and distal portions of the first three digits.
The palmar cutaneous branch of the median nerve branches off before the carpal tunnel. It innervates the middle of the palm.
Ulnar nerve: The ulnar nerve comes from under the tendon of the flexor carpi ulnaris and runs through the ulnar tunnel (or tunnel of Guyon), which is between the pisiform and the hook of the hamate. The ulnar nerve and its dorsal cutaneous, palmar cutaneous, and superficial branches innervate the medial portion of the wrist and hand and the medial one and a half digits.
Radial nerve: The radial nerve has two branches in the forearm: The deep branch runs through the posterior part of the forearm, supplying motor innervation to the extensor muscles. The superficial branch is a cutaneous nerve that runs under the brachioradialis muscle and passes through the anatomical snuff box, which is a visible depression formed near the base of the thumb by the tendons of the extensor pollicis longus and extensor pollicis brevis muscles. It doesn’t innervate any intrinsic hand muscles; instead, it innervates the skin and fascia of the lateral portion of the back of the hand and lateral three and half digits.
The arteries and veins
The ulnar and radial arteries carry blood down through the forearm into the wrist, where they anastomose (join together) to form arches. These arches, along with several branches, supply blood to the hand and digits.
Here are the arteries that enter the wrist:
Anterior interosseous artery: This artery runs from the ulnar artery anterior to the interosseous membrane. It pierces the membrane distally to join the dorsal carpal arch.
Palmar carpal branch: This branch runs from the ulnar artery over the anterior part of the wrist under the flexor digitorum profundus tendons.
Dorsal carpal branch: This branch runs from the ulnar artery across the back of the wrist under the extensor tendons.
Palmar carpal branch: This branch runs from the radial artery across the anterior wrist underneath the flexor tendons.
Dorsal carpal branch: This branch runs from the radial artery across the wrist beneath the pollicis and extensor radialis tendons.
These carpal branches of the ulnar arteries join together with the carpal branches of the radial arteries to form two arches in the wrist:
Palmar carpal arch: The area where the palmar carpal branches of the radial and ulnar arteries meet
Dorsal carpal arch: Formed by the anastomoses of the dorsal carpal branches of the radial and ulnar arteries
Next up are the arteries and branches that supply blood to the hands and fingers. They also come from the radial and ulnar arteries.
Superficial palmar arch: This arch is formed by the ulnar artery anastomosing with a superficial branch of the radial artery. It runs in front of the flexor tendons near the middle of the metacarpal bones.
Deep palmar arch: This arch is made by the radial artery and a deep branch of the ulnar artery. It runs along the bases of the metacarpals.
Common palmar digitals: These branches leave the superficial palmar arch to run along the lumbricals to the webbing of the fingers.
Proper palmar digitals: These branches start from the common palmar digitals and run along the sides of the fingers, but not the thumb.
Princeps pollicis: This artery starts at the radial artery at the palm and descends to past the first metacarpal to the proximal phalanx of the thumb. There it splits into two branches that run along the sides of the thumb.
Radialis indicis: This branch arises from the radial artery and runs along the lateral side of the index finger.
The superficial and deep palmar venous arches return blood to the heart and are located near the arterial arches. They drain into the deep veins of the forearm. Dorsal digital veins drain into dorsal metacarpal veins, which form the dorsal venous network. This blood drains into the cephalic and basilic veins.