Nerve Term Glossary

  • Allograft—a surgical graft of tissue transplanted into one individual from another individual of the same species; for example, a tendon (allograft) from a human donor transplanted into a recipient/patient with a knee injury.
  • Autograft—a surgical graft of tissue transplanted from one part of the body to another in the same organism; for example, a patient’s sural nerve (autograft) used as graft material for the same patient’s nerve repair surgery.
  • Axon—the part of a nerve cell (neuron) that transmits electrical signals.
  • Basal lamina—the innermost membrane layer of the nerve extracellular matrix that surrounds a Schwann cell. This layer remains intact when Schwann cells die and forms the tube through which a regenerating axon grows.
  • Conduit—a natural or synthetic single hollow tube-like device used in peripheral nerve repair.
  • Compression injury—“pinching” of the nerve due to space constraints, tethering of the nerve by soft tissue attachments or scar, which can lead to pain, loss of function or numbness in the affected area. Common nerve compression injuries include carpal tunnel syndrome and cubital tunnel syndrome.
  • Direct repair/direct coaptation—a surgical procedure where two ends of an injured peripheral nerve are sutured together to attempt to restore nerve function. Direct coaptation can be an effective treatment for peripheral nerve injury when no tension is generated after suturing the nerve stumps.
  • Distal—medical term for the part of the body situated farthest from the central point of attachment; for example, the distal ending (stump) of a peripheral nerve is the portion located farthest from the spinal cord relative to the injury site.
  • Endoneurial tubes—tubular shaped endoneurium, the layer of delicate connective tissue around the myelin sheath of each myelinated nerve fiber.
  • Endoneurium—the innermost sheath of extracellular matrix that surrounds an individual axon and through which a regenerating axon grows.
  • Epineurium—the outermost sheath layer of extracellular matrix that surrounds the entire nerve. Typically, it binds together multiple fascicles where each fascicle contains multiple endoneurial tubes containing axons.
  • Extracellular matrix—the connective tissue support matrix outside of the cell; in nerves, it consists of a series of concentric sheaths or tubes comprised of collagen and proteins.
  • Fascicle—a group of axon-containing endoneurial tubes wrapped in a layer of extracellular matrix called the perinerium.
  • Fully severed nerve—a nerve that has been completely cut or transected.
  • Myelin sheath—insulating fatty tissue that wraps around the axons of peripheral nerves to help facilitate signal transmission along cells.
  • Nerve transfer—the surgical transfer and connection of a functioning nerve to a damaged nerve in order to provide signals to an area of lost function. A nerve transfer necessitates transferring nerve signal capacity partially or totally from a functioning nerve.
  • Neuroma—a mass/tangled bundle of nerve fibers and scar tissue. Symptomatic neuromas can be extremely painful and may require surgical intervention to alleviate the pain.
  • Neuron—the functional unit of the nervous system. It is also called the nerve cell.
  • Partially severed nerve—a nerve that has been cut, but is still connected at some point.
  • Perineurium—the sheath of extracellular matrix that binds together multiple endoneurial tubes to form a single fascicle.
  • Proximal—medical term for a point in the body located closer to the point of reference relative to another structure; for example, the proximal end (stump) of a peripheral nerve is the portion located closest to the spinal cord relative to the injury site.
  • Remodeling—process by which an implanted biomaterial is replaced by the patient’s own tissue.
  • Revascularization—process by which blood supply to a body part, organ or biomaterial is established. Revascularization plays a key role in wound healing by allowing nutrient delivery and waste removal.
  • Schwann cells—specialized cells that support peripheral nerves by producing the myelin sheath, aiding in the cleanup process of Wallerian degeneration, and guiding new axon growth.
  • Soft tissue attachments—a fibrous band or structure that causes abnormal adherence of tissues; for example, soft tissue attachments can constrict a nerve, leading to pain, numbness and/or loss of function.
  • Tinel sign—a tingling sensation caused by light tapping over a nerve; a sign of nerve regeneration.
  • Wallerian degeneration—the process of breaking down axons and clearing cellular debris in an injured nerve, making room for new axons to grow.