why do your nerves..?

Question

why do you lose like the feeling in your fingers when like your arm is at a weird angle and the blood flow is decreased?...can you only have nerve sensors working with blood flow?

Answer 1

From this article:
http://www.madsci.org/posts/archives/dec96/850996021.Ns.r.html

Mild nerve compression causes the familiar experience of an arm or leg "falling asleep". Your arm falls asleep not because of the pressure on the nerve, but because the pressure deprives the nerve of its blood supply, a condition called ischemia. Ischemia causes changes in the excitability of nerve fibers. Initially, the nerve becomes superexcitable, and so as your arm or leg "falls asleep" you might notice a slight tingling or pickling sensation as the nerve spontaneously fires. As the ischemia continues, the nerve steadily becomes less excitable, until finally it is unable to fire at all. Once normal blood flow is restored, the nerve enters a prolonged period of superexcitability, which causes a more pronounced and disagreeable tingling, and sometimes even a cramping sensation. These sensations originate from the nerve itself and not the sensory endings; amputees can sometimes experience their non-existent limb "falling asleep"!