These are the nerves that communicate information about your environment to your brain. Your body uses this type of nerve to communicate that it is hot outside so you can start sweating to cool yourself down. Without this function your body would not be able to perceive sensations that your body experiences and would therefore not be able to react to external environmental conditions or internal body conditions.
These are the nerves that communicate instructions to your muscles in order to coordinate movement. Your body uses this type of nerve to optimize kinesthetic performance. Optimum function of this nerve type is critical for athletes. Without this function your body will not be able to move in a coordinated way or hold itself appropriately.
This nerve type can be referred to as the Organ Nerve, because that is exactly what it affects. This nerve is responsible for communicating with all of your blood vessels, heart, glands, and has control over the sympathetic and parasympathetic systems (fight or flight). Optimal function of these nerves is critical in order to have health. Needless to say without these nerves you will not be able to sustain life.
True vitality of life can only be achieved when all three of these nerve types are functioning optimally.