A couple of clarifying notes as relate to my most recent post on Neurons and Excitability…
Often, when one hears Central Nervous System the inclination is to think of the brain. This is accurate but not a complete picture. The CNS also includes a region of the spine down to about the waist line – the spinal cord. It is important to note that the spinal cord does not extend the full length of the spinal column.
Sensory information may arrive at a wide variety of points along the spinal cord or reach the brain itself. Information that is processed along the spinal cord without reaching the brain results in what we call reflexes. This is why reflexive actions occur so quickly: they need not travel the length of the spine and into the brain.