These messages travel trough bundles of axons called nerves. Nerve trunks form at nerve plexuses where the axons of some spinal nerves converge to innervate larger skeletal muscles. Most of the information for the control of body processes originates in the brain and is initially transmitted across the cranial nerves. Special sensory nerves, carry visual information from the eyes. Each nerve can be classified as a motor, sensory, or mixed nerve depending on its destination and function.
Sensory nerves lead to the brain and spinal cord and relay sensations from the body.
These sensations go unnoticed by our conscious thought because they rarely reach the cerebral cortex. Motor nerves take information from the brain and spinal cord to stimulate some response from a different part of the body. There are two subdivisions of the peripheral nervous system that issues motor commands. We voluntarily control skeletal muscles to contract with the somatic nervous system by means of the pyramidal and extrapyramidal systems. These systems contain the motor pathways to distribute the stimulus to the muscles.