What Is the Spinal Cord?

The spinal cord extends from the brain and serves mostly as a relay station connecting the brain to the rest of the body. For protection, the human spinal cord is encased by bony vertebrae. The region of the spinal cord closest to the brain connects the brain to regions of the body in that proximity. This would include the chest and arms. Moving further down the spinal cord and away from the brain, you begin to find the interconnections between the central nervous system and the lower portions of our body, such as our legs. However, because the nerve links extending from the lower extremities must move through the upper regions of the spinal cord in order to connect with the brain, damage to the upper region of the spinal cord will affect the lower as well as the upper areas of our body. Thus, if damage occurs lower in the spinal cord it may result in temporary or permanent paralysis of only the lower extremities. However, if the spinal cord is damaged higher up, it can result in paralysis of both lower and upper extremities.
 

When you would like to move a particular body part, the process (idea) originates in the brain in a region called the motor cortex. Motor means movement! Once initiated, the impulse is carried along a linkage of nerve cells to the skeletal muscle responsible for moving the limb or body part that is to move. Incredibly the whole process only requires a couple neurons linked in series connecting the motor cortex of the brain to the muscle and occurs in a fraction of a second.
 

While the motor cortex of our brain is busy sending signals to our skeletal muscle, signaling it to move, another region of our brain is evaluating and refining the movement. This region is called the cerebellum, which is behind and lower than the more recognizable parts of the brain. It is also this region of the brain that is particularly sensitive to the effects of alcohol and explains why movement becomes less refined when we are intoxicated.