The Surface Anatomy of the Wrist and Hand
Understanding the clinical anatomy of the wrists and hands is important because you need them for normal daily activity and hand injuries can be debilitating. The wrists and hands are amazing things. You use them to pick up a fork, wave to a friend, or pat your kids on the back (among so many other things!).
The fascia of the palm is thinner over both the thenar and hypothenar eminences. It thickens between the two eminences and forms the palmar aponeurosis, a central thickened portion of the deep palmar fascia, and fascial sheaths that surround the fingers. The palmar aponeurosis covers the softer parts of the hand and covers the tendons of those long flexor muscles.
The creases in the skin of the palm are fairly similar in everyone. That’s because those are the places where the skin is attached to the deep fascia below.
Here are some landmarks of the wrist and hand surface anatomy:
The tendons of the flexor carpi radialis and the palmaris longus are palpable; they’re probably visible on the anterior portion of the forearm and wrist. Clenching the fist may make them more prominent.
The pisiform bone is palpated just below the hypothenar eminence. It feels like a bony bump on the medial edge of the wrist distal to the moveable part of the wrist.
The tendons of extensor digitorum are visible on the back of the hand. They run under the skin from the wrist to the fingers, passing over the knuckles.
The head of the ulna may be visible and is palpable on the medial side of the wrist; it’s the bony bump on the medial side of the wrist proximal to the moveable part of the wrist.
The anatomical snuff box is a skin depression bordered by the tendons of the abductor pollicis longus and the extensor pollicis brevis on one side and the extensor pollicis longus on the other side. It’s visible and palpable at the base of the thumb. The radial artery and the superficial branch of the radial nerve run through this area.
Sometimes the median nerve gets squeezed and compressed inside the carpal tunnel area. This pressure causes numbness and tingling in the palm, thumb, and the first two fingers. Eventually the pressure causes sharp shooting pains in your wrist and hand, and it can become more difficult to grab and hold on to things. This pain is known as carpal tunnel syndrome. A lot of times it starts at night if your wrist is flexed while you’re sleeping. It typically starts in the dominant hand but can occur in both.
Women are more likely to suffer from carpal tunnel syndrome, maybe because the carpal tunnel is smaller in the female wrist. Following are other factors associated with carpal tunnel syndrome:
Having a wrist injury that causes swelling
Hormonal problems with the pituitary gland or thyroid
Fluid retention during pregnancy, PMS, or menopause
Repetitive use of certain types of hand tools
Arthritis in the wrist
Carpal tunnel can be diagnosed by using orthopedic tests. Diagnosis can be confirmed with nerve conduction tests, which involve placing electrodes on the hand and wrist and measuring the nerve impulses. Carpal tunnel syndrome may be treated by wearing a splint, taking nonsteroidal anti-inflammatory medications for pain relief, and by making changes in the way you work with your wrist. Surgery may be indicated if the other treatments fail.