The disappearance of the anal canal reflex belongs to one of the superficial reflexes of the human nerve reflexes, the person lies flat, the lower limbs are raised and straightened, and the external anal sphincter will be contracted by a small needle crossed in the perineal area. The afferent nerve is the pubic nerve, and the center is in the posterior horn cell column of the sacral medulla 4-5 and the anterior horn cell sex of the same segment. The external anal sphincter receives bilateral innervation from the perineal nerves. When one side of the pyramidal tract is damaged or the peripheral nerves are damaged, the anal reflex still exists, and when both sides of the pyramidal tract are damaged or the cauda equina is damaged, the anal reflex disappears. Fecal incontinence in the elderly can show that the anal canal reflex disappears. Then what is the reason for the disappearance of anal canal reflex in the elderly? The mechanism regarding fecal incontinence is not fully understood. Self-control of normal bowel health search depends on many factors: brain function fecal volume and consistency, colon transit, rectal distensibility, anal sphincter function, anorectal sensitivity and anorectal reflex. Abnormalities in any 1 or more of these factors can lead to fecal incontinence. Normal bowel movements require proper anorectal sensation. Pelvic floor receptors are considered important in detecting the presence of feces in the rectum. Patients with fecal impaction and overflow incontinence have decreased rectal sensation, and patients with traumatic and idiopathic fecal incontinence (idiopathic fecal incontinence) may have abnormal anal canal sensation. Idiopathic fecal incontinence, or neurogenic fecal incontinence, is due to progressive damage to the nerves controlling the transverse muscles of the pelvic floor and the external anal sphincter, as well as reduced internal sphincter function.