Block 6 Anatomy Pelvis Pelv Viscera Umich W Exp Prt 2

The prostate gland encircles the urethra. It circles around the first part of the urethra, the prostatic urethra. This is why urinary retention is one symptom of prostatic hypertrophy--if the prostate is enlarged, it may close around the urethra, occluding this passage and preventing urine from exiting the bladder.
The prostate would not be imaged using an intravenous urogram. In an intravenous urogram, a patient is given IV contrast, and radiographic images are taken as the contrast is excreted, passing through the kidneys, ureters, and bladder. Since the prostate is not part of this excretory pathway, it would not be viewed through this method. The prostate gland is completely extraperitoneal. Remember: the rectovesicular pouch, a fold of peritoneum that hangs between the bladder and rectum, is the lowest extent of the peritoneal cavity in males . But, the prostate is found on the posterior side of the bladder, below the point where the peritoneal membrane created this fold. So, it is an extraperitoneal organ. Finally, the lobes of the prostate are: anterior, posterior, lateral, and middle.

In females, the rectouterine pouch is a peritoneal fold reflecting from the rectum to the posterior fornix of the vagina. This means that an incision made through the posterior fornix of the vagina will allow a surgeon to enter the rectouterine pouch of the peritoneal cavity and remove the embryo. The vesicouterine pouch is a fold of peritoneum reflected from the uterus onto the posterior margin of the superior surface of the bladder--it helps to separate the uterus from the bladder. The cervix is the inferior end of the uterus which connects the uterus to the vagina. The isthmus and ampulla are parts of the uterine tube--the isthmus is the constricted part of the uterine tube nearest the uterus, and the ampulla is the dilated region that connects the infundibulum with the isthmus.

In the female pelvis, the bladder is the most anterior organ; the uterus is posterior to the bladder, and the rectum is posterior to the bladder and uterus. See Netter Plate 337 for a picture.

There are four major differences between the male and female pelvis. First, the subpubic angle and pubic arch are greater in the female pelvis than in the male pelvis. This is why B is correct-- the male pelvis has a smaller subpubic angle than the female pelvis. A second difference between the female and male pelvis is that the pelvic inlet for females is rounded, while for males it is heart shaped. Third, the pelvic outlet for females is larger than in males. Finally, the female pelvis has iliac wings that are more flared than in males.

The uvula of the bladder is an elevation on the posterior wall of the bladder. The uvula is produced by the middle lobe of the prostate gland. If the prostate becomes enlarged (either by benign hypertrophy or malignancy) the uvula can constrict the internal urethral orifice and cause difficulty in voiding the bladder. The seminal collicus is an elevation on the posterior wall of the prostatic urethra. The interureteric crest is an elevation on the posterior wall of the bladder, between the two ureteric orifices. The ampulla of the ductus deferens is the dilated part of the ductus deferens located posterior to the bladder. It joins with the duct of the seminal vesical to form the ejaculatory duct. The trigone is a triangular area on the posterior wall of the bladder. It is delineated by the two ureteric orifices and the internal urethral orifice, which form an equilateral triangle known as the trigone.

The ductus deferens carries sperm from the tail of the epididymis to the ejaculatory duct. When this cord is ligated, sperm cannot enter the ejaculatory duct, so there will be no sperm in the subsequent ejaculate. The seminal vesicles and prostate also contribute fluid to the ejaculate. However, ligating the ductus deferens will not interrupt the path of seminal fluid or prostatic fluid. So, the ejaculate will still contain both of these fluids.

The uterine vessels cross over the ureter as the ureters pass through the base of the mesometrium. Remember--the ureters must travel through the mesometrium to reach the base of the bladder. The relationship between the ureter and the uterine vessels is very important--you should remember this!
The round ligament of the uterus is a connective tissue band that attaches to the inner aspect of the labium majora and the uterus. It is found in the broad ligament, but it is superior to the ureter and the uterine vessels. The ovarian vessels are contained in the suspensory ligament of the ovary. The lumbosacral trunk is part of the ventral primary ramus of L4 united with the ventral primary ramus of L5--it contributes to the formation of the sacral plexus. The inferior hypogastric plexus lies between the pelvic viscera and the pelvic wall--it supplies sympathetic innervation to the vascular smooth muscle of pelvic vessels and parasympathetic innervation to the smooth muscles of the pelvis.

There are four major differences between the male and female pelvis. First, the subpubic angle and pubic arch are greater in the female pelvis than in the male pelvis. This is why A is correct-- females often have a subpubic angle of 90 degrees or greater. A second difference between the female and male pelvis is that the pelvis inlet for females is rounded, while for males it is heart shaped. Third, the pelvic outlet for females is larger than in males. Finally, the female pelvis has iliac wings that are more flared than in males.

The labia majora and scrotum are homologous structures. The labia minora is the female counterpart of the pentscrotal raphe. The glans of the clitoris and glans of the penis are homologous structures. Finally, the shaft of the corpus cavernosum in the female is the shaft of the clitoris, which is homologous to the shaft of the penis.

The ovarian artery has branches which supply the uterus. In fact, this artery anastomoses with the uterine artery. So, if the uterus is still bleeding after ligating the uterine artery, the ovarian artery is probably supplying the uterus. The inferior vesical artery supplies the inferior part of the bladder--it anastomoses with the middle rectal artery. The internal pudendal artery supplies blood to the perineum. The middle rectal artery supplies blood to the rectum. The superior vesical artery supplies blood to the superior bladder.

To answer this question, you need to understand what the true pelvis is. The true pelvis is the area beneath the pelvic brim (pelvic inlet), where the pelvic viscera are located. The false pelvis is the area above the pelvic brim, bounded by the iliac blades. Now, you just need to think about the structures listed and determine which ones are in which location. The femoral nerve is the structure that is not in the true pelvis. After coming off the lumbar plexus with contributions from L2, 3, and 4, the femoral nerve runs along the border between the psoas major muscle and the iliacus to travel into the lower limb. It never descends below the pelvic brim, so it is not in the true pelvis. Hypogastric nerves connect the superior and inferior hypogastric plexuses. Since the inferior hypogastric plexus is lying between the pelvic viscera and the pelvis wall, in the true pelvis, the hypogastric nerves should also be in the true pelvis. The internal pudendal artery is a branch of the anterior division of the internal iliac artery. It lies in the true pelvis and supplies blood to the perineum. The obturator artery is a branch of the anterior internal iliac artery or, if it is the aberrant obturator, the inferior epigastric artery. It is in the true pelvis, and exits the pelvis through the obturator foramen. The pelvic splanchnic nerves represent the sacral portion of the craniosacral outflow (parasympathetic) of the autonomic nervous system. They come from the ventral rami of the second, third, and fourth sacral nerves. So, that puts them in the true pelvis, too.

The uterine vessels are found in the inferior portion of the broad ligament, while the ovarian vessels are found in the suspensory ligaments of the ovaries. The suspensory ligaments of the ovaries are peritoneal folds covering ovarian arteries, veins, nerves, and lymphatics as the structures pass over the pelvic brim to reach the ovary.
The ovarian ligament proper is a round cord which attaches the ovary to the uterus, just below the entrance of the uterine tube into the uterus. The round ligament of the uterus is a connective tissue band that attaches to the inner aspect of the labium majus and the uterus--it traverses the inguinal canal and it is found in the broad ligament.

The mesosalpinx is the part of broad ligament that supports the uterine tube. The mesosalpinx extends inferiorly to meet the root of the mesovarium; it attaches the uterine tube to the mesometrium. The mesometrium is the part of the broad ligament below the junction of the mesosalpinx and the mesovarium; it attaches the body of the uterus to the pelvic wall. The mesovarium is the part of broad ligament that forms a shelf-like fold supporting the ovary--it attaches the ovary to the mesometrium and mesosalpinx. The round ligament of the uterus is a connective tissue band that attaches to the inner aspect of the labium majus and the uterus. It is found in the broad ligament, and it traverses the inguinal canal.

The mesometrium is the part of the broad ligament of the uterus that attaches the body of the uterus to the pelvic wall. The ureters pass through the base of the mesometrium as they travel to reach the bladder. See Netter Plate 346 for a picture of this relationship. The mesovarium is the part of broad ligament that forms a shelf-like fold supporting the ovary. The suspensory ligament of the ovary, which conveys the ovarian vessels, lymphatics, and nerves to and from the ovary, constitutes the lateral part of the mesovarium of the broad ligament. The mesosalpinx is the part of broad ligament that supports the uterine tube. Finally, the round ligament of the uterus is a connective tissue band that attaches to the inner aspect of the labium majus and the uterus. It lies in the mesometrium, and it is continuous with the ovarian ligament.

The ampulla is an expanded part of the lower rectum that stores feces. The transverse rectal folds are three folds in the ampulla which help to support fecal mass, but they are not the same as the actual region that stores the feces. Anal columns are longitudinal folds of mucosa over rectal vessels. They are found on the inner wall of the anal canal. Anal valves are folds of mucosa that join the anal columns at their inferior ends and create spaces between the wall and the valves known as anal sinuses.

The prepuce is a fold of smooth skin that extends over the glans clitoris. It is formed by the joining of the anterior divisions of the labia minora. The frenulum of the clitoris is a small fold found posterior to the clitoris. It is formed by the joining of deeper, posterior, divisions of the labia minora. The labia majora are fat-filled elevations of skin lying on each side of the vestibule of the vagina. The labia minora are smaller folds of skin lying medial to the labia majora. They extend posteriorly and inferiorly from the clitoris.

In females, the rectouterine pouch is a peritoneal fold reflecting from the rectum to the posterior fornix of the vagina. This means that an incision made through the posterior fornix of the vagina will allow a surgeon to enter the rectouterine pouch of the peritoneal cavity to remove the embryo. Take a look at Netter Plate 337 for a picture of this relationship. The vesicouterine pouch is a fold of peritoneum reflected from the uterus onto the posterior margin of the superior surface of the bladder--it helps to separate the uterus from the bladder. The rectovesicular pouch is only found in males--it is a peritoneal fold reflecting from the rectum to the posterior wall of the bladder.
The external os of the cervix is the part of the cervix between the vagina and the cervical canal; the internal os of the cervix is the part of the cervix between the uterus and the cervical canal. See Netter Plate 346 for a picture of these osses.

In females, the rectouterine pouch is a peritoneal fold reflecting from the rectum to the posterior fornix of the vagina. This means that an incision made through the posterior fornix of the vagina will allow a surgeon to enter the rectouterine pouch of the peritoneal cavity and remove the embryo. Take a look at Netter Plate 337 for a picture of this relationship. Entering the anterior fornix of the vagina would not allow a surgeon to enter the peritoneal cavity. The cervix is the inferior portion of the uterus which connects the uterus to the vagina--passing through the cervix would allow the surgeon to enter the uterus, but not the peritoneal cavity. The vesicouterine pouch is a fold of peritoneum reflected from the uterus onto the posterior margin of the superior surface of the bladder--it helps to separate the uterus from the bladder.

The rectum features three transverse rectal folds--these folds would be the most prominent features that you would see in the interior of the rectum if you were using a proctoscope. The tenia coli are the three bands of longitudinal muscle seen on the surface of the colon--the pattern of the teniae coli changes as the transition from sigmoid colon to rectum occurs. The sigmoid colon, like the rest of the colon, has three longitudinal muscular bands. These coalesce into two bands, anterior and posterior, on the rectum. However, none of these longitudinal muscle layers would be visible from the interior of the rectum. The rectovesical pouch is a peritoneal fold reflecting from the rectum to the posterior wall of the bladder in the male. Remember--females do not have the rectovesicular pouch. Instead, they have the vesicouterine and rectouterine pouches. Finally, the haustra are multiple pouches in the wall of the large intestine--they are not found in the rectum.

The uvula of the bladder is an elevation on the posterior wall of the bladder. The uvula is caused by the middle lobe of the prostate gland. If the prostate becomes enlarged (either by benign hypertrophy or malignancy), the uvula can constrict the internal urethral orifice and cause difficulty in voiding the bladder. The interureteric crest is an elevation on the posterior wall of the bladder, between the two ureteric orifices. The seminal collicus is an elevation on the posterior wall of the prostatic urethra. At the summit of the seminal collicus, you can find the prostatic utricle, which is a small blind diverticulum in the posterior wall of the prostatic urethra. Finally, the sphincter urethrae is a muscle which encircles the urethra and compresses the urethra. None of these other structures would be enlarged in a case of benign prostatic hypertrophy.

In females, the rectouterine pouch is a peritoneal fold reflecting from the rectum to the posterior fornix of the vagina. At its lowest extent, the rectouterine fold is draped over the posterior fornix of the vagina. This means that surgeons can make an incision in the posterior fornix of the vagina and enter the rectouterine pouch to harvest eggs from the ovaries or remove an ectopic pregnancy. Take a look at Netter Plate 337 for a picture of this relationship.