Week 7: Pelvic Bones & Perineal mm.

Question 1

What boundary of the pelvic cavity does this muscle form?

Answer 1

Structure: obturator internus mm., lateral wall

Origin: pelvic surface of ilium and ischium, obturator membrane

Insertion: Greater trochanter of femur

Innervation: Nerve to obturator internus L5, S1, S2

Main action:

• Rotates thigh laterally
• assists in holding the head of femur in acetabulum

Question 2

What boundary of the of pelvic cavity does this muscle form?

Answer 2

structure: coccygeus mm., floor of pelvic cavity

Origin: ischial spine

Insertion: Inferior end of the sacrum and coccyx

Innervation: Branches of S4 and S5 spinal nerves

Main Action:

• forms small part of pelvic diaphragm that supports pelvic viscera
• flexes coccyx

Question 3

What boundary of the of pelvic cavity does this muscle form?

Answer 3

structure: levator ani mm., floor of pelvic cavity

Origin: body of pubis, tendinous arch of obturator fascia, ischial spine

Insertion: perineal body, coccyx, anococcygeal ligament, walls of the prostate or vagina, rectum and anal canal

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

Main Action:

• forms most of pelvic diaphragm that helps support pelvic viscera and resists increases in intra-abdominal pressure

Question 4

what boundary of the pelvic cavity does this muscle form?

Answer 4

Structure: Piriformis mm., posterosuperior wall

Origin: Pelvic surface of S2-S4 segments, superior margin of greater sciatic notch and socratuberous ligament

Insertion: greater trochanter of femur

Innervation: Anterior rami of S1 and S2

Main Action:

Rotates thigh laterally

Abducts thigh

assists holding the head of femur in acetabulum

Question 5

Answer 5

Structure: Ilium

Question 6

Answer 6

structure: iliac crest

Question 7

Answer 7

structure: tubercle of iliac crest

Question 8

Answer 8

structure: anterior superior iliac spine (asis)

Question 9

Answer 9

structure: anterior inferior iliac spine

Question 10

Answer 10

structure: Posterior superior iliac spine

Question 11

Answer 11

structure: posterior inferior iliac spine

Question 12

Answer 12

structure: iliac fossa

Question 13

Answer 13

strucure: anterior gluteal line

Question 14

Answer 14

structure: acetabulum (specifically this is the lunate this implies the entire acetabulum)

Question 15

Answer 15

structure: acetabular notch

Question 16

Answer 16

structure: acetabular fossa

Question 17

Answer 17

structure: ischial tuberosity

Question 18

Answer 18

structure: greater sciatic notch

Question 19

Answer 19

structure: lesser sciatic notch

Question 20

Answer 20

Structure: pubis

Question 21

Answer 21

structure: body of pubis

Question 22

Answer 22

structure: pubic tubercle

Question 23

Answer 23

Structure: Superior Ramus of pubis

Question 24

Answer 24

Structure: Inferior Ramus of pubis

Question 25

Answer 25

structure: ischial Spine