The autonomic nervous system (ANS) is the system that controls nonstriated muscles and glands. There are three divisions of the ANS are sympathetic (thoracolumbar), parasympathetic (craniosacral), and enteric. The sympathetic and parasympathetic divisions are characterized by a two-neuron chain with two anatomic elements. The parasympathetic division is composed of the general visceral efferent fibers of cranial nerves III, VII, IX, X, and bulbar portion of XI (the cranial outflow), together with fibers arising in the S2-S4 segments of the spinal cord. General visceral afferent fibers convey both conscious and unconscious sensations from the viscera, and are involved in autonomic reflexes. Acetylcholine is the neurotransmitter at sympathetic and parasympathetic preganglionic neurons, and at postganglionic parasympathetic neurons. The peripheral ANS is under the control of higher centers in the cerebral cortex, especially the amygdale, hypothalamus, basal forebrain, ventral striatum, brainstem, and spinal cord that regulate and influence the function of its peripheral components. The history in patients with autonomic insufficiency may reveal symptoms related to orthostatic hypotension, abnormalities of sweating, or dysfunction of the GI or genitourinary tracts. Tests of thermoregulatory functions, disorders of the autonomic nervous system, anatomy of bladder, process of micturition, neurogenic bladder, etc. are other important topics which are also covered throughout this chapter.