2. Pelvic Wall and Diaphragm Muscles

Question 1

Pelvic Wall and Floor Muscles to know

Answer 1

Pelvic Wall

• Piriformis
• Obturator Internus (*same action)

Pelvic Floor
- Coccygeus
- Levator Ani
(and external anal sphincter)

• note - pelvic floor is formed by the pelvic diaphragm

Question 2

Levator ani muscles

Answer 2

Puborectalis
Pubococcygeus
Iliococcygeus

(named after their attachments)

Question 3

Why is levator ani considered to have a unique muscle action?

Answer 3

does not cross a joint

Question 4

Common disease associated one these muscles

• symptoms
• cause
• diagnosing

Answer 4

“piriformis syndrome”

• muscle irritates sciatic nerve
• leg pain, tingling in toes
• difficult to diagnose bc sciatic nerve could be pinch in many different areas (large nerve)

Question 5

Piriformis origin + insertion

Answer 5

origin
- anterior surface of sacrum between anterior sacral foramina

insertion
- medial side of superior border of greater trochanter of femur

Question 6

Piriformis innervation

Answer 6

nerves from L5, S1, S2

Question 7

Piriformis action

Answer 7

• lateral / external rotation of “extended” hip
• abduction of “flexed” up
• obturator internus and performs have same action

Question 8

Obturator Internus origin + insertion

Answer 8

origin
- deep surface of obturator membrane and surrounding bone

insertion
- medial surface of greater trochanter of femur

Question 9

Obturator Internus innervation

Answer 9

nerves from L5, S1

Question 10

Oburator Internus action

Answer 10

• external rotation of “extended” hip
• abduction of “flexed” hip
• obturator internus and performs have same action

Question 11

Obturator Internus travel path

Answer 11

• travels posteriorly
• wraps around ischial tuberosity
• 90* turn then travels anteriorly
• attaches femur

Question 12

Tendon of obturator internus separates what muscles?

Answer 12

Superior and Inferior Gemellus

Question 13

Piriformis and Obturator Internus together make the?

Answer 13

Pelvic Wall

Question 14

Levator Ani origin + insertion

Answer 14

Origin

• posterior aspect of pubis
• across obturator internus (as the tendinous arch)
• ischial spine

Insertion

• perineal membrane
• anal canal
• anococcygeal ligament

Question 15

Levator Ani innervation

Answer 15

pudendal nerve and branches directly from S4

Question 16

Levator Ani action

Answer 16

• support pelvic contents

- reinforce external anal sphincter

Question 17

Part of Levator Ani that attaches to external anal sphincter?

• attachments
• travel
• purpose

Answer 17

puborectalis

• posterior aspects of right and left pubic bone
• u-shape muscular sling around external anal sphincter
• supports external anal sphincter
• pulls anus anteriorly in position for deification

Question 18

Difference between internal and external anal sphincters

- what is unique about these muscles

Answer 18

external = skeletal muscle
internal = smooth muscle

• tonically contracted
• must relax for deification

Question 19

Coccygeus origin + insertion

Answer 19

origin

• ischial spine
• sacrospinous ligament

insertion
- lateral borders of coccyx and inferior sacrum

Question 20

Coccygeus innervation

Answer 20

branches from S3 and S4

Question 21

Coccygeus action

Answer 21

supports pelvic contents

Question 22

External anal sphincter origin + insertion

Answer 22

origin
- surrounds anal canal

insertion
- anchored to anococcygeal ligament and perineal ligament

Question 23

External Anal Sphincter innervation

Answer 23

pudendal nerve and branches directly from S4

Question 24

External Anal Sphincter action

Answer 24

closes anal canal

- tonically contracted, must relax to open