Spinal Nerves and Cutaneous Nerves Can Be Differentiated With Testing

In brief, spinal nerves are responsible for sensation in a certain area and power to certain muscles. There are thirty-one spinal nerves, numbered according to the area of the spine where they emerge. We often name nerves that are the combination of two of more spinal nerves, such as the sciatic nerve, which is the combination of lumbar nerves 4 & 5 and sacral nerves 1, 2, & 3. (The sciatic nerve is usually irritated by way of the fact that one of its five spinal nerve roots - at the level of the spine - is irritated. As I’ve written before, nerve entrapments in the periphery, outside of the spine, are rare.) Spinal nerve roots are commonly irritated.

In contrast, cutaneous nerves, which are named, are responsible for sensation in a certain area, but do not power muscles. In the absence of direct trauma or compression (including due to surgery), it’s rare to irritate these nerves.
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Even though their sensory areas overlap, in the presence of a sensory problem (numbness, tingling, pain), there’s a way to determine which is at fault. We have clinical nerve tension tests, muscle power testing, and repeated movement testing to indicate which nerve is the problem. We don’t have to guess. -- Laura