The spinal cord is required for a normal defecation reflex and voluntary control of the external anal sphincter. In regard to defecation, spinal cord injuries can be divided into two groups based on the level of injury: those that occur above the conus medullaris and those that damage the conus medullaris where the defecation reflex center is located. Immediately following a spinal cord injury, there is a loss of reflexes below the level of the injury, called spinal shock. The reflexes usually become functional again, however, and the defecation reflex is usually depressed for a few weeks eventually returns.