Extension cords are only so long. You can plug one in, and if it is 20 feet long it will reach its destination at just 20 feet. If it goes around any obstacles it will still travel 20 feet, but it will waste length going around the obstacles.
Imagine that near a wall outlet, an extension cord has to travel through a tight, narrow space and it gets caught. Now there is 1 foot of excess of cord at the plug that can’t get through. The cord only has 19 feet to reach its destination now. Every time you try to reach the cord around another corner, an obstacle near its far end, you notice excessive tension that is stressing the cord. Over time, the wear and tear on the cord will occur at this corner, rather than at the point by the plug where the cord can’t get through. Only observing the distal end where the cord is trying to reach its destination, you would think that is where the problem lies.
With further investigation along the entire length of the cord, you would discover that the cord has lost use of its full length. If you were to free up where it is caught, you would not get as much tension on the cord every time you turned the corner to your destination.
Why am I talking about extension cords? Because a nerve does the same thing: takes information from its origin at the spinal cord down a set length to a destination (i.e. the tips of your fingers). We all understand the extension cord analogy and that it can only stretch so far, but I see so many patients with distal nerve problems that originate at the neck. Many patients get surgery at the wrist or elbow based off of tests telling them they have positive distal impingement of the median, ulnar, or radial nerve. These same patients get immediate short term relief from surgery, but then they come back later with the same problem. If the surgery repaired the impingement at the far end, then why do they have the same symptoms?
It is because the nerve is getting caught as it leaves the neck and is operating with shorter length on a constant basis. The nerve is getting trapped in the musculature around the neck. As the nerves leave the spinal cord, they pass through the scalene muscles in the neck, dive under the clavicle, under the pec minor, and into the arm where they start taking different routes to their individual destinations. In this area between the spinal cord and the arm, any tension put on the nerve will limit its ability to easily reach its final destination. Then simply utilizing your hand in normal daily activity will put tension on that nerve. The tension may present at the wrist, i.e. carpal tunnel, or it may present in the forearm. This tension is often there because your nerve is operating at an abnormally shortened or tensed length because of what is going on at the neck.
So with nerve symptoms in the arm and hand, you should always check the neck. Make sure you don’t simply have hand and arm numbness because of what is going on at the neck.