Nerve fibers 2-way signal paths? Or is 1 nerve for muscle motion instruction and 1 for pain sense/ feedback?

Answer 1

Ok, starting with a simple definition of a nerve is a good spot. A nerve (sciatic nerve for example) is a bundle of neurons, and the nerve that we can see if we dissect an animal is mostly a bundle of the "axon" portions of the nerve cells (called a neuron). The axon transmits the nerve impulse from the CNS (central nervous system) to its target or from the target back to the CNS (of course the impulses are transmitted as action potentials).

So in summary, a nerve is a bundle of many many many neurons. The sciatic nerve has so many neurons, which individually are tiny in diameter (microns), but the sciatic nerve as whole itself is usually several centimeters thick!!! An important thing to remember is that neurons can only transmit signals in ONE DIRECTION!!! But a "nerve" transmits signals in both directions, because it contains some neurons that go toward the CNS, and some neurons that go away from it.


Now, of these neurons within a nerve, some of them are AFFERENT, some of them are EFFERENT (toward the CNS and away from the CNS respectively). Afferent neurons are "sensory neurons", but they dont just sense touch. There are different sensory neurons that sense different things, including:

1. touch
2. temperature
3. pain
4. proprioception (meaning your position in three dimensional space)
5. special senses, i.e. taste, smell, sound, vision, etc.

Then in nerves, you have EFFERENT neurons, which include a few types of neurons:
1. motor (to skeletal muscle)
2. sympathetic (to organs and smooth muscle)
3. parasympathetic (to organs and smooth muscle)

Now, the difficult part of studying neurobiology is that all of these afferent pathways take different routes into the CNS and within the CNS. The CNS then responds to the afferent signals with an efferent signal, and those too all have distinct pathways within the CNS and back out to the periphery (skeletal muscle, smooth muscle, organs).

Hope you can understand this!

Answer 2

The peripheral nervous system has two functional subdivisions. The sensory or afferent subdivision consists of nerve fibers that convey impulses to the central nervous system from sensory receptors located throughout the body. Sensory fibers conveying impulses from the skin, skeletal muscles and joints are called somatic afferent fibers, and those transmitting impulses from the visceral organs are call visceral afferent fibers. The sensory division keeps the central nervous system constantly informed of events going on both the inside and outside of the body. The motor, or efferent, subdivision of the PNS transmits impulses from the CNS to effector organs, which are the muscles and glands. These impulses activate muscles to contract and glands to secret; that is, they effect a motor response. Hope this clears up some confusion you may have had regarding this anatomically matter. Thank you for letting me share.

Answer 3

Nerve fibres can conduct in both ways, BUT the Synapse(functional junctions between nerves) is One Way....

The Nerve fibre for each function differs... Motor(instrucion to the muscle) fibers are different and sensory firbes are different...

Answer 4

That gives me a few thinks to think about. Interesting.