<unk> s refer to axonal projections that exit a particular region; as opposed to<unk>  projections that arrive at the region. These terms have a slightly different meaning in the context of the peripheral nervous system (PNS) and central nervous system (CNS). The<unk>  fiber is a long process projecting far from the neuron's body that carries nerve impulses away from the central nervous system toward the peripheral effector organs (mainly muscles and glands). A bundle of these fibers is called an<unk>  nerve (if it connects to muscles, then it is a motor nerve). The opposite direction of neural activity is<unk>  conduction, which carries impulses by way of the<unk> s of sensory neurons. In the nervous system there is a "closed loop" system of sensation, decision, and reactions. This process is carried out through the activity of sensory neurons, interneurons, and motor neurons. In the CNS,<unk>  and<unk>  projections can be from the perspective of any given brain region. That is, each brain region has its own unique set of<unk>  and<unk>  projections. In the context of a given brain region,<unk> s are arriving fibers while<unk> s are exiting fibers.
Efferent nerve fiber
Postganglionic nerve fibers
Preganglionic nerve fibers
Muscle spindle
Special visceral afferent fiber
Special somatic afferent fiber
Sensory nerve
Nerve fascicle