ABSTRACT
It is important to realize that these are spinal nerves, and that their relationship to the various named nerves in the body (e.g. the radial nerve) is complex. This is because at several points in the body, most notably in the axilla (armpit) and posterior abdominal wall, the spinal nerves become mixed up into interchanges known as plexuses, and the nerves that emerge from these plexuses can contain fibers from several different spinal nerves. A useful analogy is traffic coming from different origins and heading to different destinations, but sharing a stretch of motorway for a period of time. What this means functionally is that the areas innervated by an individual spinal nerve from the point of view of sensory function (the dermatome of that spinal nerve) and motor function (the myotome of that spinal nerve) can be quite different.
