Motor Neurons,Peripheral Nerve


Hello all,

What exactly is a peripheral nerve and how do you damage it? I know it can cause flaccid paralysis, but I do not know what/where it is. I am thinking they are in the limbs.

Also, with a complete transection of the spinal cord, the area under the cord is damaged.

Does this mean:

-no pain, temp, or light/crude touch sensations

-no kinesthetic sensation or refined touch/ pressure

-there will be no movement that you can control but will still have the spastic paralysis

Does a complete transection damage only the upper motor neurons?

I am trying to see if I am understanding this correctly. Help and clarification from anyone would be most appreciated.

nurseprnRN, BSN, RN

2 Articles; 5,114 Posts

Here's a great little resource to help you with SCI (spinal cord injury). You can print it out or save it (it's a PDF). Note that people with paralysis and no sensation can still have terrible spasticity below the level of the injury, too.

Upper motor neurons are in the cortex, the brain. Lower motor neurons are in the spinal cord. Here's a little video that can help you with that.

Yes, peripheral nerves are outside the spinal column. You can damage them in lots of ways-- here are a few: diabetic neuropathy you may have heard of, there are toxins that damage nerve tissue, they can get hypoxic with ischemia, and of course there's always trauma, including surgery (which is just intentional, expensive trauma). When you whap your elbow on a doorframe and the outside of your hand lights up, you have hit a peripheral nerve (the ulnar nerve, to be specific). When you cross your legs and your foot falls asleep and burns like crazy as it wake up, you have compressed your peroneal (NOT perineal, that's a bit higher up :) ) nerve and it has gotten very annoyed about it. When your dentist gives you lidocaine, that's to keep those peripheral nerves in your mouth temporarily out of the picture.


83 Posts

Thank you so much for your helpful response and links!