Central Nervous System
The vertebrate central nervous system consists of the brain and spinal cord. These lie in the midline of the body and are protected by the skull and vertebrae respectively. (see Nervous System)
The central nervous system along with the peripheral nervous system comprise a primary division of controls that command all physical activities of a vertebrate. Neurons of the central nervous system affect consciousness and mental activity while spinal extensions of central nervous system neuron pathways affect skeletal muscles and organs in the body.
The Spinal Cord:
- The spinal cord originates in the brain at the inferior end of the medulla oblongata, exiting the skull via the foramen magnum. It is wrapped in three layers of membranes, called meninges.
- The spinal cord carries sensory signals and motor innervation to most of the skeletal muscles in the body. Just about every voluntary muscle in the body below the head depends on the spinal cord for control. Similarly, most cutaneous sensation below the neck is transmitted via the spinal cord. Most of the sympathetic pathways and the lower (i.e. non-vagal) parasympathetic pathways also go through the spinal cord.
- Damage to the spinal cord, called myelopathy, can result in paraplegia or quadriplegia, depending on the level within the spinal cord of the damage.
- The brain keeps the body in order. It helps to control all of the body systems and organs, keeping them working like they should. The brain also allows us to think, feel, remember and imagine. In general, the brain is what makes us behave as human beings.
The brain communicates with the rest of the body through the spinal cord and the nerves. They tell the brain what is going on in the body at all times. This system also gives instructions to all parts of the body about what to do and when to do it.
- The brain controls and coordinates most movement, behavior and homeostatic body functions such as heartbeat, blood pressure, fluid balance and body temperature. Functions of the brain are responsible for cognition, emotion, memory, motor learning and other sorts of learning.