PERIPHERAL NERVOUS SYSTEM (peripheral nervous system): Peripheral nervous system has 31 pairs Includes the spinal nerve, 12 pairs of cranial nerves, and the autonomic nervous system. Each cranial and spinal nerve is covered by the following tissue layers. 1. Endoneurium which is a delicate layer and lies above the individual nerve fibers. Such nerve fibers are grouped together to form fascicles. 2. Perineurium is a layer of smooth connective tissue