Pelvis+Viscera+-+Lecture+Notes

=**Pelvis Viscera**=toc

Pelvis Viscera

=**Pelvis Viscera - Lecture Notes**=

[|Lecture 1]



**Lecture 1**
Urinary Bladder rests behind pubic symphysis. The uterus is posterior to the urinary bladder and is very closely associated with it, following the contour: when the urinary bladder is empty, the uterus rests on the superior surface of the bladder. Most posterior structure is the rectum. Transition of sigmoid colon to rectum occurs at S3. Rectum changes to anal canal at the pelvic floor. Extending laterally from either side of the uterus are the uterine tubes, approaching the lateral pelvic wall. At the distal end of the uterine tube is the ovaries, lying on the lateral wall of the true pelvis.

Rectum follows the posterior wall of the pelvis right down through the pelvic floor. Uterus rests on the superior surface of the empty bladder. Parietal peritoneum comes down to the pubic symphysis and reflects on the surface of urinary bladder and is the only area of the bladder in contact with the peritoneum. Peritoneium on the superior edge of the bladder then reflects on to the surface of the uterus. The point of reflection between the bladder to uterus is a recess called the vesicouterine pouch. At the reflection point, there is very lose connective tissue attaching it to the pubic symphysis – this is important because, as the bladder fills and grows superiorly, the parietal peritoneum right above the pubic symphysis separates from the abdominal wall to accommodate the filling urinary bladder. Endopelvic fascia is the loose CT in the true pelvis. Can condense into thick strands of CT call ligaments which attach to the urinary bladder, binding it to the inner aspect of the pubis (pubovesicle ligaments).

The peritenium continues to coat the uterus and reflects onto the rectum and onto the sigmoid colon to the sigmoid-mesocolon. At the point of reflection between the uterus and the rectum is the recto-uterine pouch (a.k.a. retrouterine recess, cul-de-sac, pouch of douglas). This is the lowest point in the peritoneal cavity when the woman is standing and a place for fluid in the abdominal cavity will collect. Fluid can be aspirated for analysis through the recto-uterine pouch via vaginal opening through the posterior vaginal wall. However, if a non-sterile object pierces the posterior vaginal wall, peritonitis can result. The rectum is divided into the upper, middle, and lower portions ONLY when relating to the peritoneum. There is no associated peritoneum in the lower portions. Peritoneum covers the anterior surface of the middle third only. Peritoneum covers the anterior, and right and left lateral, surface of the upper third of the rectum.

Ureter dumps into the posterior aspect of the bladder. Anteriorly, is the superior surface that is coated with peritoneum. The inferolateral surface points towards the apex which lies up agains the pubic symphysis. Radiating from the apex is the medial umbilical ligament. The posterior surface of the bladder is the base. In the female, the base is associated with the anterior aspect of the vagina; in the male, there are accessory reproductive glands. Inferiorly, is the neck of the bladder where the urethra leaves the urinary bladder and goes down to the pelvic floor. In the female, the neck of the bladder sits on the pelvic floor while, in the male, the neck rests on the prostate gland.

There a fair amount of fat in the pelvic fascia. There is a rich venous plexus called the vesicle venous plexus around the bladder. The deep dorsal vein of the clitoris goes inferior to the pubic symphysis and dumps into the vesicle venous plexus. The wall of the urinary bladder is smooth muscle and is called the detrusor muscle. As the urinary bladder fills, the bladder wall will appear thinner. The lining of the urinary bladder is transitional epithelium, allowing for the bladder to expand and contract without disrupting the epithelial lining. Empty bladder will have several cell layers but when it is full, it may only be a couple cell layers thick. The urinary bladder has a rugae in its mucosal lining when empty that flatten when it fills. There are 3 holes associated with the urnary bladder: the two ureters on either side, and a single aperture for the internal urethral orifice. These three openings form a trigone which is closely associated with the urinary wall – this results in the trigone always being smooth and without rugae (reflecting different embryonic origin). Female urethra is about 4 cm long, and is closely associated with the anterior wall of the vagina.

Classically, there is smooth muscle internal urethral sphincter under control of the autonomic nervous system. Modern textbooks say there is a smooth internal urethral sphincter in the male but there may not be one in females – there are possible circular muscle fibers in the female but do not appear to influence the flow of urine from the bladder. The smooth muscle fibers of the internal urethral sphincter blend into the urethra.

The fundus is closely associated with the uterine tubes and lies superior to the body proper of the uterus. The body is continuous with the cervix. Uterine tubes (a.k.a. fallopian tubes) extend laterally from the junction of the fundus and the body proper. Uterine tubes extend out laterally to the lateral pelvic wall and become associated with the ovaries and have fimbriae. At least one arm of the fimbriae is attached to the ovary from both sides. At ovulation, the egg ruptures from the germinal epithelium of the ovary and released into the peritoneal cavity. This is the reason why ectopic pregnancies can occur in the peritoneum. Because the uterine tubes open out into the peritoneal cavity, the peritoneal cavity in the female is not closed and is open to the outside. There’s blockages along the way, but the pathway is there. Peritoneum on the fundus, body, and cervix surface of the uterus will have peritoneal coating on the anterior and posterior surface. It also spreads laterally and extends as a double layer (laminae) from the lateral aspect of the uterus (because of the anterior and posterior coating of the peritoneum on the uterus) and is called the broad ligament. The mesometrium is the portion of the broad ligament that lies lateral next to the uterine body. The broad ligament associated with the uterine tube is called the mesosalpinx. There is a short stalk of broad ligament that extends to suspend the ovary is called the mesovarium. Surface cells on external surface of the ovary is called the germinal epithelium (misnomer: these cells are really part of the mesothelium and the germ cells are actually deep into the ovary and not on the germinal epithelium). Mesothelium of mesovarium is continuous with the germinal epithelium. Interior epithelium lining the uterine tube is continuous with the peritoneum (mesothelium) on the surface of the uterine tube; however, the epithelium inside the uterine tube are different types of cells than the peritoneum on the surface of the uterine tube.

Vagina is a muscular-fascia sheath, capable of tremendous extension, but remarkably thin walled. Normally, the vagina is a collapsed sheath and the anterior and posterior walls are in contact except at the upper end where the cervix ends. Normal vagina is 7-9 cm in length, ending blinding where the cervix projects. The cervix is oriented at an almost 90 degree angle from the vagina, so the cervix pierces the anterior wall of the vagina – as a result, the posterior vaginal wall is longer than the anterior vagina wall. The course of the vagina is oblique, directed to the sacrum, posteriorly and superiorly. There are no mucous glands in the vagina. Lubrication comes from the cervix where there are a lot of mucus glands, and the greater vestibular glands on the vulva. The cervix creates recesses called fornices where it projects into the vagina. Fornices are anterior, posterior, or lateral, circumferential to the cervix. Posterior fornix is the deepest. The posterior fornix is most closely associated with the recto-uterine pouch. Diaphragm use for contraception take advantage of the fornices (developed by Casanova!). Sensory innervation to the vagina is visceral and sensitive to stretch. There is no somatic in 4/5th of the vagina (only in the 1/5th has somatic innervation around the vestibule). At the tip of the cervix is an opening called the external os. The cervix is part of the uterus. The portion of the cervix that projects into the vagina is called the vaginal part of the cervix. The part that lies external to the vagina is called the supravaginal part. Supervaginal part of the cervix is continuous with the uterus. The isthmus is the narrow point that marks the junction between the supervaginal part of the cervix and the uterus; it also where the opening of the internal os resides. The cervical canal extends from the external os to the internal os. The myometrium is the smooth muscle of the uterine wall. There is very little myometrium in the cervix. The cervix is mostly fibrous connective tissue. The epithelial cells of the uterine cavity is sloughed off as menses; the epithelial lining of the cervix is constant, not responsive to hormonal changes, and does not slough. Vagina is the lower birth canal, female organ of copulation, and a duct for menses. The uterine cavity is very small with almost no dimension in the non-pregnant uterus; during pregnancy, it expands significantly. The uterine tube is fairly wide at the distal end and is called the infundibulum. Most of the length of the uterine tube is the ampula, where fertilization typically occurs. Then come a narrower region called the isthmus (meaning narrow region). Lastly, there is the uterine part at the junction with the uterus. Surface of the ovary is relatively smooth, coated by germinal epithelium, in prepubescent girls. As more and more ovulation occurs, it becomes more rough and pitted with scar tissue. There is a ligament extending from the lower portion of the ovary to the uterus called the ligament of the ovary. It goes toward the uterus, and then reflects towards the deep inguinal ring and is called the round ligament of the uterus.

The external os of the cervix looks like a round, oval appearance before a vaginal delivery. After the first vaginal delivery, the external os undergoes a permenent change and looks stellite. This change is universal.

In the normal position of the cervix, the angle at the external os (between cervix and vagina) should be about 90 degrees, assuming the urinary bladder is empty and the woman is not pregnant. This position is called ante-verted or ante-version. At the angle at the internal os (between the cervical canal and uterine cavity) is about 170 degrees. This position is called ante-flexion. The normal uterus is anteversion and antiflexed. If the angle of the external os increases and approaches 180 degrees, the uterus is in danger of fall into the vaginal canal. This is called retroversion. If the angle of the internal os increases towards 180 degrees, it is called retroflexion. Just because one angle increases doesn’t mean the other does.





Uterus can fall into the vaginal opening, right down into the introitus (vaginal opening), or even complete prolapse. The uterus is surprisingly mobile, including the body and the fundus. The plevic floor is essential to holding up the uterus. Thickening of the endopelvic fascia anchors the cervix and fixes it.

Transverse cervical (cardinal) ligament is the primary support for the uterus, other than the pelvic floor. It is a thickening of the endopelvic fasica.

Bimanual palpation pushes the cervix to access the size of the uterus. Culdoscopy is the procedure to enter through the posterior vaginal wall and into the retro-uterine pouch to look for pathology. Culdoscopy is no longer much used because of the success of laproscopic procedures (reduced risk of infection).

Ovaries are very difficult to palpate normally. Pathology is probably the only time the ovary is palpatable.

Pudendal nerve block administered anesthetic vaginally when preparing for childbirth. The anterior labia major is not blocked because of the innervation by the ilioinguinial nerve. There are no pain receptors on 4/5th of the vaginal wall.

Distension of the urinary bladder. Weakness of the urinary bladder can encroach on the vaginal wall. This is called a cystocele. Most of the time, it is due to weakness of pelvic floor musculature.

When the same thing happens to the urethra, it is called a urethrocele.

When the same thing happens to the rectum, it is called a rectocele.h