The spinal cord connects the entire nervous system from the brain to the rest of the body and acts like a motorway, sending information back and forth. The brain sends movement signals down and the soft tissue sends sensory information back.
To help protect us we have automatic responses which are called spinal reflexes. This means that you do not have to think about something before you do it. For example, when you touch something very hot, you immediately pull away.
This is an automatic reaction which is us reacting without sending messages back up to the brain.
The spinal cord passes through a hollow column from your neck to your sacrum called the spinal canal. These nerves leave the spine at each level through channels called the intervertebral foreman. Two nerves exit at each level, one to the right and one to the left.
At your lowest thoracic, or highest lumbar vertebrae, the spinal cord splits into the cauda equina. Imagine this like the hairs on a horses tail.