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

Painful thumbs? Numb fingers or hands? Weak grip? The nerves in the neck and the upper mid-back control the hands. Specifically, nerves C6, C7, C8, and T1. (The "C" stands for cervical, which means neck. The "T" stands for thoracic, which refers to the mid-back.) Most hand issues are a result of the nerves in the neck/upper mid-back being compressed. If someone has problems in BOTH hands, the issue is almost ALWAYS coming from the spine. While it is normal for your hand to fall asleep if you lie on it in a weird position, it is not normal to experience numbness/tingling/pain on a regular basis, even with sleeping. If I determine that your hand symptoms are indeed coming from the nerves in your spine, I treat it with two things: movements to decompress the nerves and postural correction. Posture can refer to your sitting, lounging, and/or sleeping habits. I often suggest modifications to your car seat too. --Laura