Areas of Sensation, Spinal Reflex, Head Injuries
Spinal Cord Injury
The amount of sensation lost depends on the location and damage to the spinal cord. There can be a partial or complete injury. A partial injury means that you will have some function below the level of injury. You may be able to feel and move one or both arms or legs. A complete injury means that there is no movement or sensation below the level of injury. The part of your cord injured will determine what parts of your body are affected. The worst injury is cervical or neck injuries. If one of the first four cervical nerves is damaged (C1-C4) then you may need a ventilator (breathing machine) to breath. These nerves control your diaphragm, your head and neck. Hurting C5-C8 nerves would affect your shoulder muscles, triceps, wrist and hand control. The thoracic nerves (T1-T affect chest muscles and Abdominal muscles (T9-T12). If the injury is below T8 then you probably would have good body control and would be able to sit without support. L1-L5 nerves are the lumbar nerves and control the leg muscles. This will affect your ability to walk. S1-S5 controls your bowel and bladder and your reproductive organs.
About 450,000 people have spinal cord injuries in the USA. There are about 10,000 new injuries every year usually they are male (82%) between 16- 30. Unfortunately quadriplegia (you have no function in your arms and legs) is more common than paraplegia (you cannot move your legs).
The Spinal Reflex
A reflex is an emergency feedback that bypasses the brain so there is no delay in reacting. As warning messages enter the spinal cord signals they go directly to the muscles to avoid potential threats, like moving your hand away from a hot flame. The messages eventually are sent to the brain but usually after you have reacted to the problem. When the doctor wants to test your reflexes he taps just below your knee cap with a small rubber hammer and your leg jerks up. Well that’s a reflex.