A pinched nerve occurs when the nerve is compressed in some way. A piece of disc in your back or neck pressing on the nerve, a narrowing of the spine associated with either age or arthritis, or an injury that allows soft tissue to interfere with normal nerve activity can all be causes of a pinched nerve. Pinched nerves in your arm and neck usually cause pain in your neck and arms, while compressed nerves in your back tend to produce back pain.
Numbness or altered sensation in your shoulder, arm and fingers can be sign that you have a pinched nerve in your arm or neck. MayoClinic.com explains that you could feel completely numb in the affected area, feel less sensation than normal, or experience hot or cold sensation as part of your sensory disturbance.
The compression of a nerve can be very painful. You might feeling a burning pain; tingling; pins and needles or a prickly feeling; or just a dull ache. If you have a herniated cervical disc, which is a displacement of one of the discs in your neck, the bone fragments can press on nerves leading down your arm and into your hand and cause pain in either one or both arms.
Symptoms that affect your muscles might not be as obvious as the abnormal sensations and nerve pain that you might have in your arm and neck. Spine Universe says spasm of the muscles are a possible effect of having a pinched nerve, though this is more likely to occur if you have a pinched nerve in your lower back rather than your arm. Muscle weakness in your arms can also be symptoms of a pinched nerve, due to the impaired signals that are not able to be sent effectively to your muscles.