What is a spinal cord?

The human spinal cord forms part of the nervous system. It extends from the base of the brain to the lower back. The spinal cord consists of millions of nerve fibres. The nerve fibres are surrounded by myelin, a white fibre coating that helps to conduct the messages (electrical signals) efficiently.

The spinal cord is a major pathway for messages from the brain to the body and from the body back to the brain. These messages can be divided into three groups:

  • Sensory messages (sensory pathways), which include the sensation of pain, pleasure, touch, pressure as well as telling the body when all or part of it is hot or cold
  • Functional messages (motor pathways), which control posture, reflexes, muscle tone and conscious voluntary movements
  • Involuntary messages (Autonomic pathways), which controls the cardiovascular, digestive, and respiratory systems, as well as involuntary (also known as smooth) muscles.

The nerves that branch out from the spinal cord to the other parts of the body are called lower motor neurons and dorsal root sensory neurons. These spinal nerves exit and enter at each vertebral level and communicate with specific areas of the body.

The human spinal cordis protected by the backbone or vertebral column. The human backbone is made up of 33 bones -7 vertebrae in the cervical region, 12 in the thoracic region, 5 in the lumbar region, 5 in the sacral region and 4 in the coccygeal region.

What is a spinal cord injury?

A spinal cord injury occurs when the nerves within the spinal canal are damaged.This disconnects the brain from the spinal cord below the level of injury. A spinal cord injury can be complete or incomplete. In a complete injury, nerve damage obstructs all signals between the brain and the body parts below the injury. There is no function below the level of the spinal cord injury. In an incomplete injury, there is some movement and feeling below the level of the injury. Complete and incomplete spinal cord injury can occur in both paraplegia and tetraplegia.

The severity of the injury and the level of injury (whether high or low in the spinal cord) determines the degree of lost function and dependence upon support people.The level of injury is the exact point in the spinal cord at which damage has occurred and is determined by the five regions found in the backbone, the Cervical, Thoracic, Lumbar, Sacral and Coccygeal parts of the spinal cord. Click here for more information on how level of injury affects the health of an individual.

Tetraplegia or quadriplegia is the partial or complete paralysis and loss of feeling in all four limbs, the abdominal and chest muscles. This occurs when there is an injury to the spinal cord in the neck or cervical cord region. Paraplegia results from a spinal cord injury within the thoracic, lumbar or sacral regions. People with paraplegia have full use of their hands, arms and shoulders. Paraplegia is the partial or complete paralysis of the lower portion of the body, including the legs and, in many cases, some or all of the abdomen and chest.

What are the Causes of spinal cord injury?

In 2006-7, the Australian Spinal Cord Injury Register (ASCIR) collected surveillance information on 348 new spinal cord injury cases. The main cause of spinal cord injury is traumas. In 2006-7, 272 new cases of traumatic spinal cord injury were recorded. Transport related injuries (52%) and falls (29%) accounted for over three-quarters of the 271 cases of traumatic spinal cord injury. Sporting activities accounted for 21 cases of spinal cord injury and working for income, including travel to and from work accounted for 37 cases. Click here for access to the full report.

Other causes of spinal cord injury include diseases such as transverse myelitis, polio, spina bifida, Friedreich's ataxia, and malignant spinal cord compression.

In New Zealand there are about 70 new spinal cord injury cases each year. From data collected at the Burwood Spinal Unit, causes include car accidents (38.9%), sport and recreation (24.0%), accidents in the work place (usually falls or car accidents) (14.5%), medical illness (10.3%), other (consisted largely of medical misadventure or mishap such as complications of surgical procedures) (6.5%), and accidents in the home (usually falls) (5.7%). Visit the CatWalk Trust website for more information.

The Nervous System

The human brain is remarkable. In comparison to other animals, the brain is seven times bigger than it should be for the size of the body. During evolution, it enlarged in a rather short amount of time allowing humans to surpass other primates.

Researchers now have insight into the human advantage and ways to optimize the brain. We will explore these findings as well as the intricate functions of the nervous system. > More