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Does every nerve ending send information to the brain separately? Is there a nerve path (I don't know their scientific name) from every nerve ending to the brain; or are they sent to brain from the same paths in the dorsal root ganglion? If not, how can we determine the (almost) exact location of pain in our hand?

I am not very familiar with the biology except the lessons I had taken in the high school. So please try to use daily language explaining this.

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  • $\begingroup$ This depends on what you mean by a nerve ending. An entire nerve [bundle] such as the sciatic nerve? An individual neuron within the bundle? The dendritic branches at the terminal end of the neuron? $\endgroup$ – bpedit Oct 26 '16 at 15:39
  • $\begingroup$ Nerve cells typically have many - sometimes thousands - of endings, called dendrites. The inputs from these are integrated, and cause a spike to travel along the axon. (This is a considerable oversimplification: look up "dendritic tree" for more info.) $\endgroup$ – jamesqf Nov 25 '16 at 18:27
  • $\begingroup$ sensory neurons often have a single dendrite, either synapsed to a sensory receptor cell, e.g. type I spiral ganglion neurons and inner hair cells in the cochlea. Or, the sensory neuron may have a specialised sensory dendrite, e.g. merkel's discs. $\endgroup$ – Oliver Houston Apr 25 '17 at 10:45
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There are two main structures in the human nervous system:

  • The central nervous system, which includes the brain and spinal cord
  • The peripheral nervous system, which is all of the nerves in the rest of the body (fingers, arms, feet, etc.)

image showing a simplified diagram of the nervous system, showing the outline of a human, with the brain and spinal cord colored in pink (the central nervous system, or CNS) and the rest of the nerves, shown as branches through the arms, torso, and legs, colored in blue (the peripheral nervous system, or PNS)

The signals taken by the peripheral nerves mainly travel to the brain through the spinal cord, and the brain sends signals back to the peripheral nerves through the central nervous system.

There are a lot more complex mechanisms and various exceptions, but essentially: the nervous system is a vast network of signals, and the majority of these signals travel through the spinal cord to the brain and from the brain to the target nerves.

The signals travel via different nerve "branches" — think of it like a tree of nerves, with the common root being the brain.

For more information please see:

Overview of the nervous system for dummies

Wikipedia (with strong references and lots of detailed information)

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As commented, a nerve ending is really the ending of a neuron, some sensory neurons travel directly to the brain, some form synapses in the spinal cord (most touch and pain neurons from the body), then spinal cord neurons carry the information to the brain. (Note that facial sensation is carried by cranial nerves from the brain stem).

Some, e.g. in the retina undergo some quite intensive processing before ganglion cells carry any information to the brain.

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