Nerves and Nerve Types
There three types of nerves in the central nervous system: motor neurons, sensory neurons and autonomic neurons.
Motor nerves send impulses or signals from the brain and spinal cord to all of the muscles in the body. These nerves control muscle contraction allowing movements and activities such as wiggling your fingers, walking, catching a baseball, or kicking a soccer ball.
Sensory nerves send messages from parts of the body, such as skin and muscles, back to the spinal cord and the brain. The information is then processed to let you feel pain and other sensations. Sensory nerves in the skin help you identify if an object is sharp, rough or smooth, hot or cold, or if a body part is still or in motion.
Autonomic nerves control involuntary or semi-voluntary functions, such as heart rate, blood pressure, digestion, temperature regulation, and sweating.
Some people also refer to another nerve type, called interneurons. Interneurons are located entirely within the central nervous system and interconnect other nerve cells. They act as a link between sensory neurons and motor neurons. An interneuron may receive information from sensory neurons and pass it along to the brain for processing, or it may process the information itself and send a signal to a motor neuron to act. For example, touching a hot stove generates sensory nerve signals to the interneuron. The interneuron processes the information from the sensory neuron itself and sends a signal to a motor neuron to take action. This quick reaction is called a reflex action.