Spinal cord

The spinal cord is a nearly cylindrical column of nerve tissue with a length of about 40 cm, located inside of the spine between the brain and the lower back. It performs two important functions. First plays the role of bilateral conductive path between the brain and PNS. This is achieved through sensory and motor neurons, long bundles of fibers which depart from different parts of the brain. They extend for different distances along the spinal cord, and their end most distant from the brain, affect fibers or cell bodies of sensory or motor neurons of the PNS. The signals can be transmitted through the gaps between the synapses of peripheral and spinal neurons. The second function of the spinal cord associated with the management of simple reflex actions. This task is performed by the neurons, the fibers of which extend for short distances up and down the spinal cord, and intermediate neurons transmit signals directly between sensory and motor neurons.
For example, if you accidentally touched a hot stove, pain receptors in the skin send signals by sensory fibers to the spinal cord. Part of these signals are immediately transmitted by neurons to the motor neurons that control muscles of the arms and hands, and you will quickly, automatically pulls his hand. Other signals pass up the spinal cord and are transmitted to the intermediate neurons in the motor neurons controlling the neck muscles. As a result, the head is automatically rotated in the direction of the source of pain. Next, the signals enter the brain and cause the sensation of heat and pain.