Reproductive and Genitourinary System PDF

Somatic Nerves of the Pelvis Most nerves of the pelvis are formed from the sacral plexus, except the femoral nerve (L2, L3, L4) which supplies the anterior thigh Sacral Plexus Formed from the anterior divisions of nerves which exit through the sacral foramina of the sacrum The sacral plexus is l...

Somatic Nerves of the Pelvis Most nerves of the pelvis are formed from the sacral plexus, except the femoral nerve (L2, L3, L4) which supplies the anterior thigh Sacral Plexus Formed from the anterior divisions of nerves which exit through the sacral foramina of the sacrum The sacral plexus is located posterior to the arteries and veins which supply the pelvic viscera ○ Sciatic = L4, L5, S1, S2, S3 Largest nerve Supplies the posterior thigh muscles and sensory innervation of most of the lleg and foot ○ Pudendal = S2, S3, S4 Exits the pelvis via the greater sciatic foramen (infrapiriform notch) Reenters the pelvis via the lesser sciatic foramen Courses through the pudendal canal, formed from fascia of obturator internus Motor innervation to pelvic floor muscles, external anal and urethral sphincter + sensory innervation to perineum ○ Obturator = L2, L3, L4 Exits through the obturator canal Motor and sensory innervation to medial thigh Autonomic Nerves of the Pelvis Inferior hypogastric plexus Formed from the plexus of sacral splanchnic nerves (SNS) and pelvic splanchnic nerves (PNS) ○ Sympathetics Sacral splanchnic nerves (S2-S4) Sympathetic fibres to pelvic vessels and structures ○ Parasympathetics Pelvic splanchnic nerves (S2-S4) (S2, S3, S4 keeps the shit off the floor) Innervates all viscera inferior to the splenic flexure All viscera superior to splenic flexure are innervated by the vagus nerve Gives rise to the prostatic plexus, uterovaginal plexus and vaginal plexuses Vasculature of the Pelvis The majority of the vascular supply to the pelvis originates from the internal iliac artery and its branches Bifurcation of the aorta = L4 Bifurcation of the common iliac artery = L5/S1 The internal iliac artery descends into the lesser pelvis and crosses the pelvic inlet dividing into an anterior and posterior trunk at the superior border of the greater sciatic foramen  Anterior Trunk 9 branches (3 to walls, 3 to viscera, 3 to bladder) Walls ○ Internal pudendal artery Exits the pelvis via the greater sciatic foramen with the pudendal nerve Reenters the pelvis via the lesser sciatic foramen Main artery supplying the perineum ○ Inferior gluteal artery - terminal branch of the anterior trunk, supplying the gluteus maximus m. Passes through the infrapiriform foramen ○ Obturator artery - travels through the obturator canal Visceral ○ Vaginal artery - supplies the vagina, inferior bladder and rectum in women ○ Uterine artery - descends along the lateral aspect of the uterus and anastomoses with the ovarian artery. Supplies the uterus. Runs superior to the ureter - ‘water under the bridge’ ○ Middle rectal artery - supplies distal rectum, anastomosing with the other rectal arteries Bladder ○ Umbilical artery - obliterates to form the medial umbilical ligament ○ Superior vesical artery - supplies the superior bladder - sometimes a branch of umbilical artery ○ Inferior vesical artery - supplies the inferior bladder (and prostate gland + seminal vesicle in men) Posterior Trunk 3 branches Iliolumbar arteries ○ Lumbar branch supplies the posterior abdominal wall and psoas major ○ Iliac branch supplies the iliac fossa Lateral sacral arteries Superior gluteal artery - terminal branch of the posterior trunk, supplying the gluteus minimus and medius m. ○ Passes through the suprapiriform foramen Ovarian Artery Arises from the abdominal aorta inferior to the renal arteries and superior to IMA ○ Crosses the brim and the origin of the external iliac vessels ○ Travels down the suspensory ligament of the ovary, enters the mesovarium to anastomose with the uterine artery in the broad ligament. ○ Divides into ovarian branches and tubal branches Pelvic Regions Pelvic inlet and brim The pelvic brim is the bony edge of the pelvic inlet: ○ Anteriorly = pubic crest ○ Laterally = iliopectineal line ○ Posteriorly = sacral promontory Vessels crossing the pelvic brim ○ Ovarian vessels ○ Vessels of sigmoid mesentery Inferior mesenteric artery - becomes superior rectal artery after crossing the pelvic brim Superior rectal artery Median sacral artery Ligaments Anterior and posterior sacroiliac ligaments - joint ala and sacrum Sacrospinous ligaments - join the ischial spine and sacrum Separate the greater and lesser sciatic notch Sacrotuberous ligaments - join the ischial tuberosity and sacrum Closes the greater sciatic notch → greater sciatic foramen Closes the lesser sciatic notch → lesser sciatic foramen Greater Sciatic Foramen Formed by the sacrotuberous ligament and sacrospinous ligament The piriformis m. passes through the greater sciatic foramen and divides it into the: Suprapiriform foramen Superior gluteal nerve, artery and vein Infrapiriform foramen Inferior gluteal nerve, artery and vein Sciatic nerve Pudendal nerve (upon leaving the pelvis) Internal pudendal artery and vein (upon leaving the pelvis) Lesser Sciatic Foramen Formed by the sacrotuberous ligament and sacrospinous ligament Contents Obturator internus m. Pudendal nerve (upon re-entering the pelvis) Internal pudendal vessels (upon re-entering the pelvis) Sciatic Foramen Structures Suprapiriform foramen Superior gluteal n., a., v. Infrapiriform foramen Inferior gluteal n., a., v. Sciatic n. Pudendal n. Internal pudendal a., v. Nerve to obturator internus Nerve to quadratus femoris Posterior femoral cutaneous n. Lesser sciatic foramen Exiting the pelvis Obturator internus m. Entering the pelvis Internal pudendal a., v. Pudendal n. Nerve to obturator internus Obturator Foramen Large opening in the formed by the ischium and pubi A strong membrane is attached to the margin - obturator membrane ○ Site of attachment of obturator internus + externus Contains the obturator canal which transmits the: ○ Obturator a. ○ Obturator n. ○ Obturator v.