There are two major parts of the nervous system: the central nervous system and the peripheral nervous system. The central nervous system is made up of the brain and the spinal cord. The brain serves as the body's control center. It controls motion, emotion, intellect and speech. The spinal cord sends messages to and from the brain. It is the link between the brain and all the other parts of the body, such as breathing and sleeping cycles.

The peripheral nervous system is made up of nerves that go from the spinal cord to most parts of the body (i.e. hand or foot). They include sensory and motor nerves. Sensory nerves send messages from your body to your brain about what you are feeling or "sensing" around you. Motor nerves carry messages from the brain through the spinal cord to arms, legs, and trunk, telling them when and how to move. Another part of the peripheral nervous system, the autonomic system, works the internal organs such as the heart, lungs, stomach and blood vessels. You do not consciously control this part of the nervous system.

The action of moving from one place to another can provide a simple description of how the nervous system works. The signal to move starts in the brain, travels down the spinal cord to the peripheral nerves in the trunk and legs, and movement begins - getting up and walking. We are not even aware of all the messages needed to do this which is what makes the process so amazing.

An example of how well the nervous system works is when accidentally reaching out and touching a very hot object. The sensory (feeling) nerves in the hand send the message to the brain, by way of the spinal cord, that the object is too hot to touch and causes pain. Another message is sent by way of the motor nerves to the hand to move away. This happens instantly, but depends on all parts of the nervous system working. How a person with a spinal cord injury feels and moves is affected by where the injury occurs (see table below). For example, a person with a spinal cord injury touches something hot and the message is sent from the hand to the spinal cord and begins to travel up the spinal cord to the brain. However, when the message reaches the part of the spinal cord that is damaged, the message is blocked. The brain doesn't get the message and can't tell the body to move, so a burn can occur.

Following a spinal cord injury, damaged nerve tissue may be permanent. If it does return, recovery may take a long time, and function may not be completely normal. In order to maintain good health, you must know what damage has occurred and take the necessary steps to compensate.

Spinal Cord Functional Levels

Note: As the levels go down you will be able to do everything described above the level of your injury. Functional abilities depend on many other factors, such as age, having a good support system, and general health.

LEVEL	MUSCLES CONTROLLED BY THAT LEVEL	FUNCTIONAL ABILITIES
Cervical 1, 2 and 3	Limited neck control	Unable to breathe without equipment
Cervical 4	Good neck control	Able to breathe without equipment
Cervical 5	Biceps - bringing hand to mouth	Able to feed self, use computer and telephone with special equipment
Cervical 6	Wrist movement	Able to push own wheelchair, bathe and dress upper body
Cervical 7	Triceps - bringing hand down; bend fingers	Able to transfer in and out of wheelchair, drive with special equipment, do most or all of own care
Thoracic 1 and 2	Finger movement	Able to perform self-care and have wheelchair mobility independently
Thoracic 3, 4, 5 and 6	Intercostals - muscles between the ribs	Stronger cough
Thoracic 6 to 11	Trunk balance	Everything mentioned above and better balance
Thoracic 12 to Lumbar 2	Hip flexors—lifting leg	Able to walk short distances and use crutches
Lumbar 3 and 4	Hip abductors and quadriceps—moving leg in and out , kicking	Able to walk with short leg braces
Lumbar 4 to Sacral 3	Toes and ankles	Able to walk without equipment
Sacral 2 to 4	Bowel, bladder and sex organs	Management of bowel and bladder with equipment