Illustrations
Trigger finger
The flexor tendons bend the finger. They run across the palmar surface of the finger through a series of tunnels, or "pulleys". There are 5 main pulleys, A1, A2, A3, A4, and A5. The A stands for "annular", or ring shaped. (There are also some thinner pulleys called the cruciate pulleys which are not shown here.) As the finger bends and straightens, the flexor tendons glide through the annular pulleys.
Sometimes, one of the tendons will develop a nodule around the A1 pulley. When this happens, the tendons can no longer glide smoothly through the pulleys when the finger beds and straightens. The catching of the tendons in the A1 pulley may cause the finger to pop or lock. This condition is called a "trigger finger". Surgical treatment of this condition involves cutting the A1 pulley so that the flexor tendons no long get caught. Because the A2, A3, A4, and A5 pulleys are not disturbed, the tendons still function normally.
Carpal tunnel syndrome
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The carpal tunnel is a structure at the wrist formed by small bones (the floor and sides of the carpal tunnel) and the transverse carpal ligament (the roof of the carpal tunnel). Nine tendons and one nerve run through the tunnel as they travel from the forearm to the hand. The nerve is called the median nerve. The median nerve provides sensation to some of the fingers and motor function to some of the hand muscles. When the tendons in the carpal tunnel become inflamed or when the roof of the carpal tunnel becomes thickened, there is less space in the tunnel and it gets very tight. This increases the pressure on the median nerve. The compressed nerve becomes irritable and loses function. This condition is called "carpal tunnel syndrome" and is marked by loss of sensation, tingling, pain and/or weakness in the hand. Surgical treatment of carpal tunnel syndrome involves cutting the transverse carpal ligament to relieve pressure in the carpal tunnel and decompress the nerve.
