A 17 year old girl is brought into the casualty with severe abdominal pain and a fever. Laboratory examination is remarkable for an elevated white blood cell count and a pregnancy test is positive. Upon questioning, it is determined that she attempted to terminate her pregnancy by inseing a sharp object into her vagina. The physician determines that the wall of the posterior fornix of the vagina has been penetrated. Into what region did the sharp object penetrate?
Deep perineal pouch Ischioanal space Rectouterine space Rectovesical space