A pinched, compressed, or entrapped nerve can be surrounded by swollen tissues or impinged upon by bony processes in many areas of the body.
The cause can be injury, disease, or even pregnancy.
The result is pain, numbness, tingling, and weakness in the part of the body to which the nerve normally carries impulses.
One kind of nerve entrapment, carpal tunnel syndrome, is produced in the wrist because of repetitive stress from movements like typing; the resulting swollen tissues compress the median nerve, which runs through a bony tunnel in the wrist called the carpal tunnel.
Similar problems can affect the ulnar nerve, which runs through the elbow, and another nerve in the arm, the radial nerve.
The pain of sciatica results from compression of the sciatic nerve, which runs down through the buttocks to the back of the leg. The cause is often a herniated spinal disk; normally, this gelatinous cushion with a tougher outer ring separates the vertebrae, but injury can squeeze out the soft core so it puts pressure on a nerve.
A pinched tarsal nerve or plantar nerve can cause numbness in the foot. Some other commonly compressed nerves include the femoral nerve, which extends from pelvis to knee, and the peroneal nerve, along the side of the leg.