Figure 7a. (a) Transverse T2-weighted fast spin-echo (2,500/100) MR image obtained through the upper part of the anal sphincter with an endoanal coil and (b) corresponding drawing in an asymptomatic 30-year-old female volunteer show the internal sphincter (IS), longitudinal muscle (LM), puborectal muscle (PR), vagina (V), urethral mucosa and submucosa (MS), urethral smooth muscle (SM) and striated muscle (ST), urethropelvic (or parapelvic) ligament (UP), and parapelvic ligament (PU).