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Muscles of Pelvic Walls and Floor (Floor (Coccygeus mm. (Proximal…
Muscles of Pelvic Walls and Floor
Lateral Wall
Obturator Internus mm.
Proximal Attachment: pelvic surfaces of ilium and ischium; obturator membrane
Distal Attachment: greater trochanter of femur
Innervation: nerve to obturator internus
Action: rotates thigh laterally; assists in holding femur head in acetabulum
Floor
Coccygeus mm.
Proximal Attachment: ischial spine
Distal Attachment: inferior end of sacrum and coccyx
Innervation: branches of S4 and S5 spinal nerves
Action: forms part of pelvic diaphragm that supports pelvic viscera; flexes coccyx
Levator ani mm. (puborectalis, pubococcygeus, and iliococcygeus)
Proximal Attachment: body of pubis; tendinous arch of obturator fascia; ischial spine
Distal Attachment: perineal body; coccyx; anococcygeal ligament; walls of prostate or vagina, rectum, and anal canal
Innervation: nerve to levator ani (branches of S4), inferior anal (rectal) nerve, and coccygeal plexus
Action: forms most of pelvic diaphragm that helps support pelvic viscera and resists increases in intra-abdominal pressure
Postero-superior Wall
Piriformis mm.
Proximal Attachment: pelvic surface of S2-S4; superior margin of greater sciatic notch and sacrotuberous ligament
Distal Attachment: greater trochanter of femur
Innervation: anterior rami of S1 and S2
Action: rotates thigh laterally; assists in holding femur head in acetabulum