While musicians may not know exactly know how nerve compression works, we may know the physical sensations or have heard of them- numbness and tingling in the fingers, an inability to hold things or grip them, and sometimes tendonitis as well! Nerve entrapment is when a nerve becomes compressed by surrounding tissues or irritated from sustained holding positions, misuse, overuse, etc. For musicians, there are three nerves of the upper arm which are often affected: the radial nerve, the ulnar nerve, and medial nerve. These nerves originate from the cervical spine and top of the thoracic spine (aka. they start in the neck and upper back), move through the brachial plexus, and can be affected by movement patterns, lack of blood flow, tendonitis, etc. along the way to the hand.
The two most common areas of nerve entrapment affect the ulnar nerve via the elbow and median nerve via the wrist. Carpal tunnel syndrome refers to the area in the wrist where nerves and flexor tendons pass through to the hand. Tendonitis and inflammation in these flexors can press on the nerve, which might be caused by overuse, misalignment in technique, or repetitive trauma. This could be because of how a student holds his or her instrument or bow, how he or she plays at the piano, or even types at the computer. For string players, extreme wrist extension (elevated wrist when holding bow with fingers below) can also accelerate these issues.
Cubital Tunnel Syndrome affects the ulnar nerve, and refers to the cubital tunnel in the elbow region where the nerve passes to the ulna. The ulnar is the largest unprotected nerve in the body, meaning that it has very little soft tissue and muscle to protect it. Each time you bend your elbows, your ulnar nerve is slightly compressed which is normal, but sustaining bent elbows for many hours a day can wreak havoc on this sensitive nerve. Most musicians need to bend their elbows to 90 degrees to simply hold their instruments, and then add to that driving, computer use, eating, and sleeping, which can equal 20 hours of bent-elbow motion a day! Also factor in that oboists and bassoonists will make reeds, most likely with bent elbows and sitting over a reed desk. Compression in the ulnar nerve may lead to numbness and tingling in the pinky/ring side of the hand as well as the ulnar side of the forearm.
Lastly, radial nerve compression will affect the thumb side of the hand. (Remember last week's radius vs. ulna mini anatomy lesson?) This can occur in the elbow as well, though it will be in the inner pit of the elbow, unlike the ulnar nerve. There can also be compression as the nerve travels into the hand, along the thumb side. Excessive pronation, bow gripping, and over-gripping an instrument, can contribute to these issues.
Now this may look rather bleak, especially when nerve compression is coupled with surrounding tissue inflammation or tendonitis, but we'll take a look at some prevention strategies next time, as well as common treatments.