Nerve fibers sometimes called axons are filamentous projections of many individual neurons called nerve cells The most known is the peripheral nerves. The nerve fiber bundles within the brain and spinal cord are referred to as nerve tracts or pathways. Nerve fibers carry information from a receptor or sense organ . Messages are sent by electrical impulses propagated along the fibers. some carry only sensory or motor fibers but most carry both. nerve functioning is sensitive to pressure, hot , cold, and injuries.
A peripheral nerve can be damaged by:
When a nerve experiences an injury that severs some or all conducting fibers by cut or crush nerve injury has occurred. Surgical repair is possible except for nerves in the brain and spinal cord.
The injuries that involve crush injuries where the nerve trunk itself remains intact and individual fibers within a peripheral nerve are severed. The severed fibers degenerate on both sides causing loss of strength in a muscle or loss of sensation in the skin area. If the ends are still aligned new fibers can grow and regenerate. They begin to repair in a few days after the injury.
Total severance from things like accidents with bullets, knifes, power tools, flying glass, car accidents and any other penetrating injury. The ends of the cut nerves are separated and there is an absence of direct contact a lump of tissue forms as the nerves try to regenerate. This causes no recovery of function so it is very important that the ends of nerves are brought together and stitched.
Regenerating nerve fibers sometimes pass down the wrong channels and the function may not be the same as before. Movement skills and interpretation of sensations may be restored or partially restored with physical therapy.
The brain and spinal cord nerve tracts are structurally different from peripheral nerves. If nerves become severed they do not regenerate.
Pain in an area supplied by a nerve or tingling, weakness, and numbness means a nerve may be compressed or stretched. Carpal tunnel syndrome where pain in thumb, middle finger, and index finger is where pressure is on the median nerve that passes through the wrist. The prolapsed disk has pressure on the nerve root leading from the spinal cord sends pain down back and legs. The radial nerve is pressed against the humerus (upper arm bone) the pain runs down to wrist and hand is known as crutch palsy.A damaged nerve takes time to heal. Sometimes surgical decompression is used to relieve pressure.