pelvis 2

Question 1

What is the major blood vessel of the pelvis?

Answer 1

• internal iliac artery

Question 2

Where does the piriformis muscle originate?

Answer 2

• pelvic surface of the sacrum; sacrotuberous ligament

- inserts at the upper end of the greater trochanter

Question 3

What are the nerves that innervate the piriformis muscle?

Answer 3

• Sacral S1-S2

Question 4

Where does the tendinous arch attach?

Answer 4

• levator ani and obturator internus

Question 5

What is the function of the puborectalis muscle?

Answer 5

• relaxes which decreases the angle between ampulla of the rectum and upper portion of the anal canal to aid in defication

Question 6

What happens after evacuation?

Answer 6

• the puborectalis and anal sphincters contract to close anal canal

Question 7

What is the process of defecation?

Answer 7

• initiated by distention of rectum with stool in sigmoid colon
• afferent impulses transmitted to SC by pelvic splanchnic nerve which increases peristalsis (contracts smooth muscles)
• SNS cause decrease in peristalsis and maintains tones of internal sphincters

Question 8

What is above the piriformis muscle?

Answer 8

• superior gluteal artery and vein (L4-S1)

- leaves pelvis through greater sciatic foramen

Question 9

What is below the piriformis muscle?

Answer 9

• inferior gluteal artery and vein (L5-S2)

- leaves pelvis through the greater sciatic foramen

Question 10

What is the nerve supply to the floor of the pelvis?

Answer 10

• ventral rami of L4-5 of the lumbosacral trunk
• ventral rami of S1-4 of sacral trunk
• innervation lies mostly on internal surface of piriformis muscle

Question 11

What is the balance of L4?

Answer 11

• L4 part of femoral nerve
• L4 part of obturator nerve
• joins L5 to form the lumbosacral trunk

Question 12

What passes through the piriformis muscle?

Answer 12

• slips of nerves that will form the sciatic nerve

Question 13

What are the branches of the internal iliac artery?

Answer 13

Anterior
- inferior gluteal, internal pudendal, umbilical, obturator, middle rectal, uterine arteries
Posterior
- ilolumbar, lateral sacral, superior gluteal arteries

Question 14

What innervates the obturator internus muscle?

Answer 14

• nerve to obturator internus

Question 15

What innervates the obturator externus muscle?

Answer 15

• obturator nerve

Question 16

What is the path of the internal pudendal artery?

Answer 16

• arises from internal iliac artery
• leaves pelvis by greater sciatic foramen between piriformis and coccygneus and enters perineum through lesser sciatic foramen by hooking around ischial spine

Question 17

What nerve accompanies the internal pudendal artery along its path?

Answer 17

• pudendal nerve

Question 18

What artery does the external pudendal artery arise from?

Answer 18

• femoral artery

Question 19

Why do we have to potty train kids?

Answer 19

• corticospinal tract is under-developed to control BM
• when developed the motor fibers to the cortex synapse on spinal nerves in ventral horn and exit to supply the skeletal muscles of rectum (puborectalis)

Question 20

Prostatic venous plexus

Answer 20

• allows dorsal vein to return to this plexus
• ## continuous supply of blood

Question 21

What is the ischioanal fascia?

Answer 21

• semi liquid fat at body temperature that helps with defecation (allows distention of anal canal)

Question 22

Where does the external iliac artery leave the pelvis?

Answer 22

• through the obturator hiatus

Question 23

How are seminal vesicles related to exocrine functions?

Answer 23

• they are lobulated glandular structures
• produce seminal fluid
• lower ends become ducts that join vas deferens to form ejaculatory ducts

Question 24

What is special about the superior rectal artery?

Answer 24

• its the termination of the inferior mesenteric artery
• divides into 2 branches to follow sides of rectum and anastomoses with middle (internal iliac) and inferior rectal (internal pudendal) arteries