Bony Pelvis and Pelvic Viscera

Question 1

Levator Ani (puboccygeus and iliococcygeus)

Answer 1

Makes up the Pelvic Diaphragm

Origin:
Body of pubis, tendinous arch of levator ani, and ischial spine

Insertion:
Perineal body, coccyx, anococygeal ligament, walls of prostate or vagina, rectum, and anal canal.

Innervation:
Nerve to levator ani (branches of S4), inferior anal (rectal) nerve, coccygeal plexus

Action:
Helps support pelvic viscera; resists increases in intraabdominal pressure

Question 2

Coccygeus

Answer 2

Makes up the Pelvic Diaphragm

Origin:
Ischial Spine

Insertion:
Inferior end of sacrum and coccyx

Innervation:
Branches of S4 and S5

Action:
Forms small part of pelvic diaphragm that supports pelvic viscera; flexes coccyx

Question 3

Piriformis

Answer 3

Origin:
Pelvic surface of 2nd–4th sacral segments; superior margin of greater sciatic notch and sacrotuberous ligament

Insertion:
Greater trochanter of femur

Innervation:
Anterior rami of S1 and S2

Action:
Laterally rotates hip joint; abducts hip joint; assists in holding head of femur in acetabulum

Question 4

Obturator Internus

Answer 4

Origin:
Pelvic surface of ilium and ischium; obturator membrane

Insertion:
Greater trochanter of femur

Innervation:
Nerve to obturator internus (L5, S1, S2)

Action:
Laterally rotates hip joint; assists in holding head of femur in acetabulum

Question 5

Pubic Symphysis

Answer 5

Symphysis joint

Question 6

Sacroiliac joints

Answer 6

Anteriorly:
Plane Synovial Joint

Posteriorly:
Syndesmosis