How can nerve damage cause fecal incontinence?

If nerves controlling the anal sphincters malfunction, proper muscle action is impaired, and fecal incontinence (unintended passage of stool) may occur. If sensory nerves are damaged, it becomes difficult to perceive that there is stool in the rectum. The pudendal nerve (which controls the muscles of the pelvic floor) is the major nerve supplying the external sphincter. Nerve damage resulting in incontinence can occur when the pelvic floor muscles are stretched or traumatized by childbirth or repeated straining to defecate, or if a person develops a neurological condition (such as multiple sclerosis, stroke, diabetic neuropathy, or spinal cord injury).