What events are responsible for these defects? One theory says that an important cause of prolapse and pelvic floor dysfunction is likely to be partial denervation (Swash et al 1985, Smith et al. 1989). But Pierce et al. (2008) demonstrated in nulliparous monkeys that bilateral transection of the levator ani nerve resulted in atrophy of denervated levator ani muscles but not in failure of pelvic support. This indicates that connective tissue components could compensate for weakened pelvic floor muscles. According to South et al. (2009), in up to 30 percent of all vaginal childbirths, pelvic floor muscles are.
