The brain and spinal cord together form the body's central nervous system, which acts as the coordination and relay station for information about the outside world. Without a central nervous system you would be unable to think or feel, to voluntarily move, or even to breathe.
The spinal cord acts as the body's telephone system, relaying information from the brain to the rest of the body, and sending signals about the rest of the body to the brain. This vital role means that, even if the rest of your body is functioning perfectly normally, a spinal cord injury can undermine even the most basic functions.
So, What Does the Spinal Cord Do?
When most people refer to the spine, they mean the spinal cord plus the bones that surround it. The spinal cord itself is a long bundle of nerve cells encased in the 33 vertebral bones known individually as vertebra.
The spinal cord is the body's central processing center, receiving information from the brain and sending it to branching nerves that connect with every other area of the body. It also receives signals from the body, sending those signals to the brain to allow you to appropriately react to everything from cold weather to intense anxiety.
Because the spinal cord both sends and receives important information about the body and the surrounding environment, it is indispensable to the regulation of a range of bodily functions, including:
- Regulating heart rate.
- Assessing temperature, and helping your body appropriately respond to cool or warm itself when temperatures are inappropriate.
- Maintaining homeostasis—relatively consistent internal body conditions. By sending signals about the body's state, the spinal cord allows the brain to react with signals that initiate a cascade of changes. For example, if the spinal cord sends signals to the brain indicating that you are cold, you may begin shivering or seek out a blanket.
- Regulating breathing.
A spinal cord injury can interfere with a range of functions. In general, the higher the injury, the more extensive the disability will be, since your spinal cord typically will be unable to process signals below the site of the injury. Very high spinal cord injuries may necessitate the use of a respirator and other artificial devices. You might also need help with basic functions, such as using the restroom.
Coordinating Reflexes
The spinal cord also coordinates most reflexive responses, allowing you to quickly respond to changing stimuli without consciously becoming aware of the change. If you brush your hand against a hot stove, pain signals quickly tell your spinal cord to react, allowing you to pull your hand away. Reflexive responses mean that you may react before you actually know what you're reacting to, since the spinal cord initiates the response before the brain can process the physical sensation.
If you experience a spinal cord injury, you may experience difficulties with reflexes, depending upon the location of the injury. This can increase your risk of certain injuries.
Parts of the Spinal Cord
The spinal cord acts as a single unit, receiving signals and sending them up the brain, and coordinating signals to send outward to the rest of the body. It is also a collection of specific sub-parts, each with its own function. Nerve tracts exit the spinal cord and travel across the body from the spine at following regions:
- Cervical spinal cord: Consisting of eight bones, descending from C1-C8, this region plays a role in critical functions such as breathing and movement of the upper torso. Injuries to the cervical spine almost inevitably result in quadriplegia, paralysis of all four limbs. Injuries high in the cervical spinal cord can be fatal.
- Thoracic spinal cord: Consisting of 12 bones, descending from T1-T12, the thoracic spinal cord helps coordinate movement in the lower body. Injuries to this region often result in quadriplegia, paralysis below the waist.
- Lumbar spinal cord: Consisting of five bones, descending from L1-L5, the lumbar spinal cord coordinates sensations in lower regions of the body. The effects of damage to this area vary greatly, but lumbar spinal injuries sometimes impede bladder and sexual function.
- Sacral spinal cord: Also consisting of five bones, descending from S1-S5, sacral spine injuries can undermine sensation in lower regions of the body, as well as chronic pain.
- Coccyx: Known sometimes as the coccygeal spine or tail bone, this region consists of between three and five distinct bones that may be fused together.
