Any damage to the spinal cord is a very complex injury. People who are injured are often confused when trying to understand what it means to be a person with a spinal cord injury (SCI). Will I be able to move my hands? Will I walk again? What can I do? Each injury is different and can affect the body in many different ways. The following is a brief summary of the changes that take place after a spinal cord injury. It tells how the spinal cord works and what some of the realistic expectations are for what a person should eventually be able to do following a spinal cord injury.
The Normal Spinal Cord
The spinal cord is a part of your nervous system. It is the largest nerve in the body. Nerves are cord-like structures made up of many nerve fibers. The spinal cord has many spinal nerve fibers that carry messages between the brain and different parts of the body. The messages may tell a body part to move. Other nerve fibers send and receive messages of feeling or sensation back to the brain from the body, such as heat, cold, or pain. The body also has an autonomic nervous system. It controls the involuntary activities of the body; such as, blood pressure, body temperature, and sweating.
The nerve fibers that make up the communication systems of the body can be compared to a telephone system. The telephone cable (spinal cord) sends messages between the main office (the brain) and individual offices (parts of the body) over the telephone lines (nerve fibers). The spinal cord is the pathway that messages use to travel between the brain and the other parts of the body.
Because the spinal cord is such an important part of our nervous system, it is surrounded and protected by bones called vertebrae. The vertebrae, or backbones, are stacked on top of each other. This is called the vertebral column or the spinal column. The vertebral column is the number one support for the body. The spinal cord runs through the middle of the vertebrae (figure A).
The spinal cord is about 18 inches long. The cord extends from the base of the brain, down the middle of the back, to about the waist. The bundles of nerve fibers that make up the spinal cord itself are Upper Motor Neurons (UMNs). Spinal nerves that branch off the spinal cord up and down the neck and back are lower motor neurons (LMNs). These nerves exit (figure C) between each vertebrae and go out to all parts of the body. At the end of the spinal cord, the lower spinal nerve fibers continue down through the spinal canal to the sacrum, or tailbone.
The spinal column is divided into four sections. The top portion is the cervical area. It has eight cervical nerves and seven cervical vertebrae. Moving down the back, the next section is the thoracic area. It includes the chest area and has twelve thoracic vertebrae. The lower back section is the lumbar area and has five lumbar vertebrae. The bottom section has five sacral vertebrae and is the sacral area. The bones in the sacral section are actually fused together into one bone.
Source: Jackson, A.B. (2000). Overview of spinal cord injury anatomy and physiology. Retrieved from http://www.spinalcord.uab.edu/show.asp?durki=32105&site=1021&return=21475 on August 20, 2012.