A nerve in the neck becomes pinched when something invades the space normally occupied by the nerve. This may be a herniated disc, a bone spur, a tumor or swollen tissue from a traumatic injury. Just as there are a number of potential causes, the effects of a pinched nerve in the neck are multiple.
Anyone who has ever bumped his "funny bone" knows what nerve pain is all about. Pain from a pinched nerve in the neck will have many of the same characteristics as the "funny bone" pain of striking the ulnar nerve near the elbow. The quality of the pain tends to evoke the intense, distinctive sensation of electric shock. Another feature of nerve pain is its radiating quality. Pinching a nerve at one location will tend to cause pain that radiates all along the course of the nerve. For many of the nerves in the neck, this will mean pain into an arm.
In most cases when a nerve in the neck is being pinched, there will be certain positions or movements that reduce the pinching and others that increase the pressure on the sensitive nerve. Since it is natural to avoid pain when possible, a pinched nerve will result in a voluntary or involuntary avoidance of offending movements and positions. The resulting loss of mobility will tend to be asymmetrical as the pinched nerve will usually be on one side only.
The nerves passing between the vertebrae of the neck do not just carry pain information but they also provide other sensory information to the brain. Numbness or tingling can be an effect of a pinched nerve. The specific location of the numbness or tingling can be an important clue as to the location of the pinched nerve. The sensory area, or dermatome, served by the C6 nerve, for example, includes the thumb and index finger. According to Dr. Craig Scanlan of the University of Medicine and Dentistry of New Jersey, the nerves most commonly pinched in the neck are at the C7 and C6 levels.
Just as the nerves of the neck provide sensory information from specific areas, muscles are also served by specific nerves. This means that a pinched nerve in the neck often results in weakness. Donald Murphy, in his book, "Conservative Management of Cervical Spine Syndromes," describes how a pinched C5 nerve may cause weakness in the shoulder muscles. A C6 nerve that is pinched will affect the strength of the wrist extensors and a C7 pinched nerve tends to weaken the wrist flexors.