Michael Dauzvardis, Ph.D Know your Pelvis I + II Michael Dauzvardis, Ph.D

Pelvis: objectives List the bony/ligament components and describe sexual differences in these components. Contrast how the greater and lesser sciatic foramina are defined. Describe the major muscles of the pelvis along with their actions and innervations. Sketch the branches of the internal iliac artery. Draw the major branches of the lumbar-sacral plexus and the segmental contributions to each (e.g., pudendal - S2, 3, 4). Describe the importance of the pectinate line with respect to the vasculature and lymphatic drainage of the rectum and anal canal. 7. Appreciate the major viscera found in the pelvis with special attention to the uterus.

Bones of the pelvis 1—coxal bone 2—sacrum 3—acetabulum 4—obturator foramen The male has a narrower angle between the inferior pubic rami, narrower pelvic outlet, and more vertical iliac crests. Bones of the pelvis

Ilium

Ischium Greater sciatic notch Ischial spine Lesser sciatic notch Ischial tuberosity

Pubis Superior ramus Pectineal line Pubic tubercle Pubic crest Pubic body Obturator foramen Inferior ramus

Meet the true pelvis

LIGAMENTS OF THE PELVIS: A. Pubic Symphysis: Joins the two pubic bones B. Sacroiliac Ligaments: From iliac to sacral tuberosities C. Iliolumbar Ligaments: L5 transverse process to iliac crest Sacrotuberous Ligament: from lateral sacrum and coccyx to the medial side of the ischial tuberosity. E. Sacrospinous Ligament: from lateral sacrum and coccyx to ischial spine

Ligaments continued-- In the female the distance between the ischial spines (interspinous distance) can be useful in determining if a caesarian delivery is indicated Left sacrospinous ligament is removed

Main contents of the pelvis Rectum Bladder Uterus/vagina; prostate in males

Muscles of the pelvis; Obturator internus Dauzvardis Obturator internus

Muscles of the Pelvis; Piriformis Dauzvardis Piriformis (nerve to piriformis)

Muscles of the pelvis: Pelvic diaphragm piriformis The pelvic diaphragm consists of levator ani + coccygeus The levator ani inserts on the fascia of the obturator internus on an arc called the arcus tendinaes

Muscles of the pelvis: levator ani The levator ani forms the main part of the pelvic diaphragm, the cranial layer of the pelvic floor. It is primarily supplied by direct branches of the sacral plexus (S3-S5). To a small degree the pudendal nerve contributes to its innervation as well. Muscles of the pelvis: levator ani Levator ani = iliococcygeus plus pubococcygeus

Muscles of the pelvis: coccygeus Levator ani COCCYGEUS Levator ani + coccygeus = pelvic diaphragm—Keeps your guts from falling out

Arteries of the pelvis--overview

Pelvic arteries; male

Pelvic arteries: female In the female the uterine artery replaces the inferior vesicle artery such that branches off the uterine and vaginal arteries feed the inferior bladder

Pelvic innervation Sacral Plexus: (L4 - S5): rests on piriformis muscle, see figure above. It gives several branches to pelvis and perineum. Represents ventral rami of S1 - S4; and receives L4,L5 contribution from the lumbosacral trunk.

Pelvic innervation 1----subcostal 2----iliohypogastric 3----ilioinguinal 4----genitofemoral 5----lateral femoral cutaneous 6----obturator 7----femoral 8----superior gluteal 9----inferior gluteal 10—nerve to piriformis 11---peroneal portion of sciatic 12---tibial portion of sciatic 13---nerve to quadratus femoris and inferior gemellus 14---nerve to obturator internus and superior gemellus 15---posterior femoral cutaneous 16---perforating cutaneous 17---pudendal 18---nerve to levator ani Faraz has been spotted putting ketchup on a hotdog

Autonomics Lumbar splanchnics (sympathetic), sacral splanchnics (sympathetic), and pelvic splanchnics (parasympathetic) mingle with the aortic, mesenteric, and hypogastric plexi to innervate pelvic viscera.

Autonomics--continued Note; sympathetic splanchnics fail to synapse in chain ganglia-they synapse in ganglia in or near target organs.

Sacral splanchnics Pelvic splanchnics Sacral symp. ganglia Ganglion impar Autonomics—even more Just a nice summary slide showing how sympathetic lumbar and sacral splanchnics come off chain while pelvic splanchnics come off ventral roots (not pictured)

Autonomics ad nauseum The key points to remember from these obnoxious autonomic figures:   Lumbar and sacral splanchnics are sympathetic Pelvic splanchnics are parasympathetic All 3 splanchnic types mingle with all or some of the SHP, IHP, and pelvic nerves Parasympathetics make you go and point, (erection) while sympathetics make you stop going and shoot (ejaculate) Anatomy is not always the bomb Point and shoot

Pelvic viscera: rectum Rectouterine pouch Rectovesical pouch in males

Pelvic viscera: rectum Site of internal hemmorhoids Valves of Houston Note: internal anal sphincter is under involuntary control—other 3 are under voluntary control (hold it!!-you can’t always blame the dog) A rise in portal venous pressure can result in hemorrhoids where the inferior rectal veins (systemic) meet the middle rectal veins (portal).

Pelvic viscera: bladder Relaxed by parasympathetics Activated by parasympathetics Pee and stop peeing

Pelvic viscera: prostate The prostate secretions are alkaline in order to neutralize the sperm killing acid environment of the vagina It has been said that the prostatic utricle is a remnant of the uterus in males. Colliculus means “little hill” and it is here where the ejaculatory ducts open. It is also called the Verum Montanum---?????

Pelvic viscera; seminal vesicles Looks like the head of an evil wasp to me. Secretions include: sugar fructose, proteins, citric acid, inorganic phosphorus, potassium, and prostaglandins

Pelvic viscera: uterus

Pelvic viscera: Let’s build a uterus The uterus is a pear shaped hollow organ which lies between the rectum (posteriorly) and the bladder (anteriorly) of the female. The lumen of the uterus is continuous with the lumen of the uterine tubes.

The fundus is the rounded upper part of the body

The body makes up 2/3 of the uterus—1/3 cervix

The cervix in the inferior 1/3, body—superior 2/3, fundus—superior rounded part of the body. The cervical os is the opening into the uterus----It becomes more slit-like after child birth OS

The uterine tubes are approximately 4 inches long The uterine tubes are approximately 4 inches long. They are attached to the fundus of the uterus. The lumen of the tube is continuous with the lumen of the uterus. The tube forms a direct connection between the uterine cavity and the peritoneal cavity. It carries the ovum to the uterine cavity. Implantation in the tube or even in the peritoneal cavity can occur and can be fatal. The tube is divided into isthmus, ampulla, infundibulum, and fimbriae.—and lies in the upper border of the broad ligament.

The ovary is located on the lateral pelvic wall and is attached to the posterior leaf of the broad ligament by the mesovarium (mesentery of the ovary). The ligament of the ovary slings ovary to the uterus and runs in the mesovarium. It is related to the gubernaculum of the testis. The round ligament connects the uterus to the labia majorum. The suspensory ligament of the ovary suspends the ovary laterally to the pelvic wall. It is a condensation of fascia surrounding blood vessels to the ovary and is technically part of the broad ligament. The blood supply is via the ovarian artery from the aorta.

The broad ligament is a fold of peritoneum which extends from the sides of the uterus to the lateral wall of the pelvis. It surrounds the uterine tubes. Laterally the broad ligament is prolonged over the ovarian vessels as the suspensory ligament of the ovary.—Again—the mesentery of the tube is the mesosalpinx and the ovary the mesovarium. Transverse cervical ligaments: from cervix to lateral walls. Uterosacral ligaments from cervix posteriorly to sacrum.

ureter Uterine artery passes above ureter in base of broad ligament—remember: WATER GOES UNDER THE BRIDGE!---urine passes under the uterine artery.---many law suits following ligation of ureter during hysterectomy. Ovarian artery comes from aorta and travels in suspensory ligament. It gives off a small tubal branch . Textbooks differ—but Pansky says that the uterine and vaginal arteries arise independently from the anterior division of the internal iliac artery. The vaginal arises from the uterine in 10% of cases. The vaginal replaces the inferior vesical in the male and thus gives off small inferior vesical branches to the bladder. (a little diff from my artery drawing based on Netter in my pelvis lecture) REMEMBER! Water under the bridge---ureter is under uterine artery.

Pelvic viscera: uterus—the real deal Left tip of forceps is touching ovary—right tip near fimbria—Note round ligament

Pelvic viscera: uterus--summary