What is the major blood vessel of the pelvis?
- internal iliac artery
Where does the piriformis muscle originate?
- pelvic surface of the sacrum; sacrotuberous ligament
- inserts at the upper end of the greater trochanter
What are the nerves that innervate the piriformis muscle?
- Sacral S1-S2
Where does the tendinous arch attach?
- levator ani and obturator internus
What is the function of the puborectalis muscle?
- relaxes which decreases the angle between ampulla of the rectum and upper portion of the anal canal to aid in defication
What happens after evacuation?
- the puborectalis and anal sphincters contract to close anal canal
What is the process of defecation?
- 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
What is above the piriformis muscle?
- superior gluteal artery and vein (L4-S1)
- leaves pelvis through greater sciatic foramen
What is below the piriformis muscle?
- inferior gluteal artery and vein (L5-S2)
- leaves pelvis through the greater sciatic foramen
What is the nerve supply to the floor of the pelvis?
- 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
What is the balance of L4?
- L4 part of femoral nerve
- L4 part of obturator nerve
- joins L5 to form the lumbosacral trunk
What passes through the piriformis muscle?
- slips of nerves that will form the sciatic nerve
What are the branches of the internal iliac artery?
Anterior
- inferior gluteal, internal pudendal, umbilical, obturator, middle rectal, uterine arteries
Posterior
- ilolumbar, lateral sacral, superior gluteal arteries
What innervates the obturator internus muscle?
- nerve to obturator internus
What innervates the obturator externus muscle?
- obturator nerve
What is the path of the internal pudendal artery?
- 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
What nerve accompanies the internal pudendal artery along its path?
- pudendal nerve
What artery does the external pudendal artery arise from?
- femoral artery
Why do we have to potty train kids?
- 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)
Prostatic venous plexus
- allows dorsal vein to return to this plexus
- ## continuous supply of blood
What is the ischioanal fascia?
- semi liquid fat at body temperature that helps with defecation (allows distention of anal canal)
Where does the external iliac artery leave the pelvis?
- through the obturator hiatus
How are seminal vesicles related to exocrine functions?
- they are lobulated glandular structures
- produce seminal fluid
- lower ends become ducts that join vas deferens to form ejaculatory ducts
What is special about the superior rectal artery?
- 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
