I — Puborectalis; 2 — Pubococcygeus; 3 — Iliococcygeus; 4 = 1 + 2 + 3 — Levator ani; 5 — Anococcygeal body; Anococcygeal ligament; 6 — Coccyx [coccygeal vertebrae CoI-CoIV]; 7 — Sacral hiatus; 8 — Ischial spine; 9 — Ischiococcygeus; Coccygeus; 10 — Piriformis;
II — Sacral canal; 12 — Sacrum [sacral vertebrae SI-SV]; 13 — Vertebra LV; 14 — Promontory; 15 — Anterior superior iliac spine; 16 — Anterior sacro-iliac ligament; 17 — Arcuate line; 18 — Obturator fascia; 19 — Tendinous arch of levator ani; 20 — Pubic symphysis; 21 — Deep
transverse perineal muscle
