The nerves that control urination and defecation are called autonomic nerves, which belong to the autonomic nervous system. This system has a certain degree of independence and is not governed by the subjective will of the person, and is able to move autonomously, hence the name, and is also called the involuntary nervous system or vegetative nervous system. Its main function is to regulate the activities of smooth muscles of internal organs and blood vessels, cardiac muscles and endocrine glands, and is composed of two main parts: sympathetic and parasympathetic nervous systems. It relies on the smooth muscles of the intestine and the anal sphincter for stool control and on the smooth muscles of the bladder and the sphincter of the urethra for urine control. The sympathetic and parasympathetic nerves maintain dual innervation of various smooth muscles and sphincter muscles, which interact and antagonize each other to control stool and urine.