Pre-Final

Question 1

Origin + insertion of obturator internus muscle

Answer 1

Origin: obturator membrane
Insertion: greater trochanter of the femur
-The fibers converge towards ischial spine, then obturator internus exits pelvic cavity through LESSER SCIATIC FORAMEN, then it will turn 90degrees to insert on greater torchanter of femur.
-Fx: lateral rotation of thigh
-innervation: nerve to obturator internus (part of sacral plexus)

Question 2

Origin + insertion of piriformis

Answer 2

• Origin: anterior aspect of sacrum
• Insertion: greater trochanter of femur
• Exits pelvic cavity through GSF
• Fx: lateral rotation of thigh
• Innervation: nerve to piriformis (also part of sacral plexus)

Question 3

What is the pelvic diaphragm (pelvic floor)?

Answer 3

• Funnel-shaped, separates true pelvic cavity from perineum

- Partially covers obturator internus m.

Question 4

What 2 striated muscles make up the pelvic floor?

Answer 4

1. Levator ani

2. Coccygeus

Question 5

Where does coccygeus originate?

Answer 5

Origin: ischial spine + sacropspinous ligament
Insertion: inferior part of sacrum and coccyx
Innervation: branch of sacral plexus (nerve to coccygeus)
Fx: supports pelvic viscera

Question 6

3 parts of levator ani (3 muscles):

Answer 6

1. Puborectalis m.
2. Pubococcygeus
3. ilioccygeus

Question 7

Origin of levator ani

Answer 7

pubis, tendinous arch

Innervation: branch of sacral plexus

Question 8

What is the ischioanal fossa?

Answer 8

Wedge-shaped space on either side of anus. L and R fossa communicate POSTERIOR to anal canal.

• Medial wall: perineal surface of pelvic diaphragm (levator ani + coccygeus), blends w/external anal sphincter
• Lateral wall: obturator internus

Question 9

What is the tendinous arch?

Answer 9

fascial layer between obturator internus and levator ani

Question 10

What is the pudendal canal?

Answer 10

• Encloses the internal pudendal vessels and pudendal nerve while they are traveling in the ischioanal fossa
• It is on the medial side of the obturator internus

Question 11

What is the course of the pudendal nerve?

Answer 11

• Emerges from sacral plexus
• Leaves pelvic cavity through GSF
• Travels around ischial spine and through LSF to enter the pudendal canal in the ischioanal fossa
• Travels in medial surface on obturator internus muscle

Question 12

Anterior recess of ischioanal fossa

Answer 12

Between pelvic diaphragm and perineal membrane

Question 13

Posterior recess of ischioanal fossa

Answer 13

Between pelvic diaphragm and gluteus maximus
*impt - infections involving ischioanal fossa can spread to contralateral buttock and/or anterior or posterior recesses of ischioanal fossa. Pus limited by fibrous septa throughout fat in fossa.

Question 14

Superior to pectinate line:

• Embryol:
• Blood Supply:
• Venous:
• Lymph:
• Nerve

Answer 14

Endoderm
Superior rectal artery (branch of IMA)
Superior rectal vein –> IMV –> Portal vein
Pre-aortic nodes