Above: Spinal cord (Wikimedia Commons/BruceBlaus)
Whether it was an injured athlete or a car accident victim, you’ve probably seen paramedics treating someone with a head injury. One of the first things they do is put on a neck brace in order to stabilize the spine and protect the spinal cord.
Did you know? Aside from injury, spinal cord damage can also be caused by diseases that attack the spinal cord, such as multiple sclerosis, or diseases that cause the vertebrae to wear down, exposing the cord.But what exactly is the spinal cord, and why is it so important? The answers to these questions will help you understand why the location of a spinal injury is extremely significant.
The spine and spinal cord
The spinal cord is a bundle of nerve cells that starts at the bottom of your brain and ends in your lower back. By sending signals through this cord, your brain and body are able to communicate.
Because the spinal cord is so fragile, it’s protected by a stack of rigid bones called vertebrae that surround the cord and form your spinal column, or spine. From top to bottom, the vertebrae are organized into four main regions: the cervical (C), thoracic (T), lumbar (L), and sacral (S) segments.
Within each region, the vertebrae are numbered from top to bottom. In total, there are 7 cervical vertebrae (C1 to C7), 12 thoracic vertebrae (T1-T12), 5 lumbar vertebrae (L1-L5), and 5 sacral vertebrae (S1-S5). The sacral vertebrae are fused together and are collectively known as the sacrum.
This system is also used to organize the spinal cord itself, which is divided into the same regions. A pair of spinal nerves branch off from each region of the cord and lead to a specific part of the body. These nerves allow your brain to send commands to muscles so you can perform movements. They also send information from your body back to your brain so you can sense things like pain, temperature, and where your limbs are.
What causes a spinal cord injury?
The most common cause is a motor vehicle accident, but whenever there is an impact to the head, neck or back, there is the chance of a spinal cord injury. For example, one could occur when diving headfirst into water or falling on your head while snowboarding. If vertebrae are fractured, or moved out of place, the cord can become exposed—at which point it can be compressed, stretched, torn, or punctured. And when the spinal cord is damaged, it can no longer properly transmit signals between the brain and the body.
Why is location so important?
Doctors describe spinal cord injuries based on the location where the damage occurs, because this determines the severity of the injury. The spinal cord is organized so that the higher regions control your arms and back, and the lower regions control your legs. And because the cord acts as a relay system, all of the regions below the level of the injury are also cut off from the brain. So the higher the level of the injury, the more severe the effects.
|Diagram showing where nerves connected to different parts of the body connect to the spinal cord. Click image to enlarge (Wikimedia Commons/Ralf Stephan)
Did you know? The majority of spinal cord injuries occur in young people under the age of 30. Over 80% of victims are male. If the lower part of your spinal cord is damaged—for example, at the L1 level—you won’t be able to feel or move your legs. This is known as paraplegia. But if the cord is damaged at the C6 level, you will lose the function of both your arms and your legs. This is known as quadriplegia. And injuries at the cervical level usually result in the patient being unable to move.
In addition, the main muscle that controls breathing, the diaphragm, is controlled by nerves from the C3-C5 levels. That means that if a person’s spinal cord is damaged at or above this level, they may not be able to breathe on their own. This was the case with the actor Christopher Reeve, who suffered an injury at the C1-C2 level after falling off of a horse. In addition to being paralyzed, he was also dependent on a ventilator in order to breathe.
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Researchers continue to make great strides in developing new treatments for spinal cord injuries. In cases where the cord is only partially damaged, it may even be possible to regain some function over time. But the best treatment is still prevention. Never dive into shallow water, always wear a helmet when playing sports, and remember to buckle up when you’re in a car!
Resources freely available online
New hopes, new dreams (2001)
Roger Rosenblatt, Time
Magazine article on Christopher Reeves’ experience with spinal cord injury.
J. J. Como. E. R. Sutton. M. McCunn, R. P. Dutton, S. B. Johnson, B Aarabi & T. M. Scalea. (2005). Characterizing the need for mechanical ventilation following cervical spinal cord injury with neurologic deficit. The Journal of Trauma 59(4), 912-916.
Scientific article discussing factors affecting whether a person with spinal cord injury will require help breathing. An abstract is available on the journal’s website. A subscription is required to view the full text.
R. J. Dumont, D. O. Okonkwo, S. Verma, R. J. Hurlbert, P. T. Boulos, D. B. Ellegala & A. S. Dumont. (2001). Acute Spinal Cord Injury, Part I: Pathophysiologic Mechanisms. Clinical Neuropharmacology 24(5), 254-64.
Scientific article discussing factors affecting the severity of spinal cord injuries and the implications for treatment. An abstract is available on the journal’s website. A subscription is required to view the full text.
L. H. Sekhon & M. G. Fehlings. (2001). Epidemiology, demographics, and pathophysiology of acute spinal cord injury. Spine 26(24 Suppl), S2-12.
Scientific review article providing a global perspective on the epidemiology, demographics, and pathophysiology of acute spinal cord injury. An abstract is available on the journal’s website. A subscription is required to view the full text.