Burns, frostbite, and cutting of the arms and legs may be painful. Similarly arthritis, abscesses in the bones and soft tissues, tumors and damage to the nerves may result in severe pain.
From the limbs of the body the nerves pass along until they connect with the roots in the spinal cord. Pressure, irritation or damage to these nerves at any point along their course may result in pain that is felt in the limb itself.
Pain may also be transmitted to the limbs from impulses arising elsewhere in the body. For instance, pain from the hip may be transmitted to the knee. Pain from the deep muscles of the back or from the small bones of the spinal column may be felt in the legs. Pain from angina pectoris or coronary thrombosis of the heart may be felt along the inner sides of the arms.
Various disturbances of the blood supply to the limbs may result in pain. This applies particularly to blocking of the circulation so that the tissues do not receive a proper amount of oxygen. As the blood supply becomes blocked there is a feeling of numbness and finally difficulty of movement. You say “My leg has gone to sleep.” Blocking the blood to the arm causes the fingers to get quite numb in about twelve minutes, and then they are painful when touched. As the blood returns a sensation of tingling is felt, which is due to renewed activity of the nerves of the arm. If an arm or leg is moved while the circulation is blocked severe pain may be felt. This may be called a cramp, although actually the muscles are not in spasm but flaccid.
After a limb has been amputated pain may be felt as if it were in the limb. This is called “phantom limb” pain.
In diagnosing the causes of pain in the extremities the character and location of the pain are most significant.