Spinal cord 1

[MCBCON]

Just posting this information because I think folks here might find it informative.

from: http://www.clevelandclinic.org/health/health-info/docs/2000/2036.asp?index=8720

The Spinal Cord and Injury
The nervous system is divided into two major divisions: the peripheral nervous system and the central nervous system. The peripheral nervous system is a network of nerves throughout the body, handling everything from regulating the heart rate to flexing the hand or foot. It also receives information, much of which is sent to the brain (e.g., pain, temperature). This information is analyzed and coordinated by the central nervous system.

The central nervous system is made up of the spinal cord and brain. The spinal cord runs from the base of the brain down the middle of the back and ends just above the waist. It is made up of nerve cells (neurons) and long nerve fibers called axons that relay all incoming information from the rest of the body to the brain and all outgoing information from the brain to the rest of the body. Unlike the nerves of the peripheral nervous system, those in the central nervous system do not regenerate once they have been injured. So when the spinal cord is injured, a patient will suffer varying degrees of paralysis if these axons become destroyed.

Thirty-three ring-shaped bones called vertebrae form the spinal column (spine) and protect the spinal cord from injury. If these bones are broken or damaged, paralysis is not necessarily the result once the bones are stabilized. Therefore, a person may break his or her back or neck without suffering paralysis. It is when the damage reaches the spinal cord that serious, long-term or permanent effects often result. The extent and region of the body affected by this damage depends upon the region of the spinal cord that is injured.

The spinal column and spinal cord consist of four regions, with each region controlling a particular part of the body. These regions can be categorized even further into 31 pairs of peripheral spinal nerves. These nerve pairs extend from the spinal cord through spaces in the vertebrae, connecting the spinal cord with other nerves throughout the peripheral nervous system. In general, the higher the spinal cord is injured, the more severe the injury. The regions of the spine are numbered in descending order from the brain.

Cervical Region (C1 to C8): Located in the neck, this region controls the back of the head, the neck, shoulders, arms, hands, and diaphragm
Thoracic Region (T1 to T12): This region is located in the upper back and controls the torso and parts of the arms
Upper Lumbar (L1 to L5): Located in the middle of the back just below the ribs. The upper lumbar region controls the hips and legs
Sacral Segments (S1 to S5): Just below the upper lumbar region in the middle of the back. This region controls movement in the groin, toes, and some parts of the legs
There are two types of spinal cord injuries: complete and partial. If a spinal cord injury is complete, there is no function below the point of injury. This means the patient will experience no sensation or voluntary movement and that both sides of the body, for example have both arms, will usually be equally affected. A complete injury can result in the paralysis of all four limbs (quadriplegia) or the lower half of the body (paraplegia).

For partial injuries, a patient may be able to move one limb more than the other or be able to feel more with one side than the other. The level of incomplete injuries may vary from patient to patient, and can affect the body in different ways. For example, a C-6 injury may result in having no hand control but having wrist control. A C-5 injury may deprive a patient of wrist and hand control, but not arm and shoulder control.

Aside from a loss of sensation and movement, patients with a spinal cord injury may also experience bladder and bowel complications. Spinal cord injuries often affect fertility in males. If the spinal cord injury is high, for example C-1 or C-2, the patient may need a respirator or diaphragmatic pacemaker to breathe properly.

Other complications that may result from a spinal cord injury are an inability to regulate blood pressure, low blood pressure, reduced control of body temperature, an inability to sweat that occurs below the level of injury, and chronic pain. Patients with spinal injuries also have an increased susceptibility to respiratory disease and autonomic dysreflexia.

Autonomic dysreflexia is primarily the result of the body being unable to control the blood pressure. This is especially a concern for patients who have a spinal cord injury at T-6 or above. The signal responsible for "telling" the blood vessels to relax cannot be processed because of the injury. With autonomic dysreflexia, these blood vessels intermittently remain constricted, thus elevating the blood pressure and possibly leading to life-threatening complications such as stroke. External methods of lowering the blood pressure to a safe level are often necessary.