My understanding of the "sensory pathway" is that its a linear, directional pipeline as follows:
- Nerves (fire various signals depending on the type of sensors they are)
- Fibers (transmit signals from nerves to spinal cord)
- Spinal cord (transmits signals from fibers to brainstem)
- Brainstem (transmits signals from spinal cord to brain)
- Brain (the somatosensory cortex register signals as pain/pressure/temperature/etc.)
So again, my understanding is that sensory nerves are 1-way sensors, and that once they fire a signal, its 1 and only ultimate destination is the brain.
So, as a precursor to my question, if anything I have stated is incorrect, please begin by correcting me!
I read that pinched nerves in the back and neck can cause neuropathy ("pins and needles") all over the body: hands, feet, face, etc.
But how can this be? If my understanding of the sensory pathway is correct, then a pinched nerve in one's neck should only send "pins and needles" signals directly to the brain; it should not at any point forward/relay signals on to any other areas of the body.
To state that a pinched nerve in one's neck could possibly cause neuropathy in their arm, then that insinuates there is some connection between the pinched "neck nerve" and the nerve(s) in the arm that are experiencing the pins and needles sensation.
In fact, unless I completely misunderstand the entire sensory pathway and how pain signals transmit, this implies that a pinched nerve sends signals out to the spinal cord, down the spinal cord and into, say, an arm, and that the sensory receptors in the arm subsequently react to these signals.
How is this possible?!? Is there some kind of feedback mechanism at play where nerves in the neck and back can relay signals on to other areas of the body, instead of just feeding directly into the "spinal cord => brainstem => cortex" pipeline?