Just as a kink in a garden hose can impede the flow of water, the impingement of a nerve can affect the transmission of nerve impulses to and from the brain. The spinal cord is encased in the flexible, bony confines of the vertebral column, where a contiguous series of vertebrae provide protection while allowing freedom of movement. A biomechanical mishap, such as trauma to the spinal column, can shift the vertebrae and compress the spinal nerves.
Referred Pain
Often the impingement of a spinal nerve will cause pain in another part of the body. This pain reflects the path of the particular nerve that has been affected, and reveals some information about the sensory regions it serves. The pain caused by a pinched nerve may become worse upon movement of the affected area of the spine.
For instance, orthopedic surgeon Peter Ullrich of NeuroSpine Center of Wisconsin notes that sciatica, a condition characterized by pain radiating down the back of the legs, can be caused by a pinched nerve of the lower spine. The sciatic nerve is composed of nerves that originate in the lower lumbar and sacral regions of the spinal column.
Numbness and Tingling
Some pinched nerves may cause no pain or the complete absence of sensation in the regions supplied by that nerve. The American Academy of Orthopedic Surgeons explains that decreased nerve impulses due to a pinched nerve may result in numbness, or in some cases paresthesia, the tingly "pins and needles" sensation commonly associated with having an appendage "fall asleep."
The brachial plexus is a network of nerves formed from the lower four cervical nerves, plus the first thoracic nerve. Numbness that radiates into the arm or shoulder can be caused by an injury to the nerves of the cervical spine, which supports the neck. Thoracic nerves are those that exit through the chest and ribcage area of the spine.
Muscle Weakness
The motor nerves are those specifically destined to terminate within muscle tissue, where they supply the muscles with nerve impulses that instruct them on when and how to move. Impingement of a spinal nerve can sometimes affect motor function and cause muscle weakness, according to MayoClinic.com. Spasticity of the muscles is another possibility associated with a pinched spinal nerve, and some patients may experience muscle twitching as a result.
