11.12 Pelvic Viscera Flashcards
What is the most anterior structure in the pelvic viscera? Describe its shape
Bladder is the most anterior of the pelvic viscera.
It is shaped like a pyramid that is tipped to the side…
The apex of the pyramid points towards the pubic bone anteriorly and the base is posteriorly.
What is the trigone of the bladder?
A triangular area located within (interiorly) the bladder at the base that has smooth walls (c.f. the loose folds making bumpy mucosa).
- On either side of the upper corners are the ureter openings into the bladder
- The tip of the triangle (points down) and is where the urethra drains.
What are the major parts of the bladder?
- Apex – superiorly and anteriorly pointing towards the pubic symphysis.
- Body – The main part of the bladder, located between the apex and the fundus
- Fundus (or base) – Located posteriorly. It is triangular shaped, with the tip of the triangle pointing backwards.
- Neck – narrowing that joins the bladder to the urethra (is posterioinferior)
All pelvic viscera require stabilisation. Where is the bladder stabilised from?
Stabilisation happens at the neck of the bladder by ligaments (mainly pubovesicle) - connecting to the pubic bone anteriorly. Ligments of the pelvis are condensations of the loose connective tissue around the nerves and vessels.
This is because you can’t stablise the fundus of the bladder because it needs to expand for urine collection.
The posterior wall (base) of the male bladder is related to several important structures.
What are they and describe their anatomical relationship to the bladder.
Components of the male genitourinal tract.
- The prostate gland is immediately related to neck of bladder and surrounding first part of the urethra.
- The vas deferens is directly related to the last parts (just before entry point) of the ureters. They run over the top and cross over them on either side.
- The seminal vesicles also rest on the inferior part of the base of the bladder just under the vas deferens course and empties into the prostate glands
Describe the path of the ureters from the kidneys down to the bladder
Ureters (on psoas in line with tip of transverse processes) Pelvic part of the ureters dip of pelvic brim (narrowing) running on lateral wall of the pelvis and crosses towards the posteiror aspect of the bladder (base) to enter at upper point of trigome.
Describe the path of the vas deferens from the testes to the prostate gland (with special mention of the relationship to the bladder)
The vas deferens originates at epididymis of testes and ascends and traverses the inguinal canal through the superficial ring, inguinal canal and exits deep ring (def. in transversalis) along lateral wall of pelvis and approaches the base of the bladder from behind crossing the ureter and joins the duct of the seminal vesicle and form an ejaculatory duct (final common pathway) and enters the urethra.
A structure does cross the ureters in the female anatomy. What is this? Describe
The uterine artery travels towards the uterus (from side walls on top of ureter towards uterus).
Describe the prostate gland
What structure supports it?
It situated between neck of bladder and the urogenital diaphragm. It is often described as chestnut sized.
Levator ani (pubo prostaticus) sits on the lateral side of it (slings surrounding the prostate holding it and the bladder in position).
What is special about the prostatic part of the urethra?
It has a crest/mound/bulge called the prostatic crest with the opening of the ejaculatory duct on each side and the opening of the prostatic ducts into it.
Describe the relationship of the prostate gland to the rectum.
How is this applicable to the clinical setting?
The prostate sits just anteriorly to the rectum.
The posterior surface is palpable on per rectal examination. Anterior tip of the fingers on the anterior wall is the prostate gland: size and consistency can be felt.
What is the most important lobe of the prostate gland? Why is this so?
The median/middle lobe (the star on the diagram)
This is the part that enlarges on BPH. Cancer the gland becomes very hard and loses the typical contour (palpable on examination). But for BPH it doesn’t lose normal contour but does enlarge (it is still rubbery).
Between prostatic part of the urethra and the ejactulatory duct and thus has an impact on flow of urine.
What is the most common positioning of the uterus in relation to the vagina? Describe it
Anti-verted and anti-flexed
The uterus is bent forwards on the vagina and superior bladder.
- Anti-verted means bent forwards on the top of vagina
- Anti-flexed means it is bent forwards on itself
What is uterine retroversion?
Uterus can be anything between anteverted to retroverted (bends back on vagina and directly relates to rectum
Rectroversion related to back pain in period and during labour
How does the uterus size vary with pregnancy?
Uterus size varies w/ number of pregnancies (never completely involutes back). It is often described as having the dimensions 8x5x3cm
Describe the shape of the uterus
It is a hollow structure with a triangular cavity pointing downwards. Each upper angle is related to a uterine tube.
What are the main parts of the uterus?
- Fundus is the convex part of uterus which houses the entry of uterine (fallopian) tubes.
- Below that is the Body of the uterus and it tapers down in size
- The bottom 1/2 cm of the body becomes the isthmus which is continuous with the cervix.
Describe the cervix and its openings
Cervix is usually 2-3cm in length
- It has an internal uterine opening (opening that relates to the uterine cavity itself called the internal os)
- There is also an external opening into the cavity of the vagina called the external os (this is what is visible and palpable on vaginal examination and is what is scarped in pap smears.
How is the cervix related to the vagina?
Cervix sits down into the opening of vagina so the vagina extends up and cups the external os. This creates the fornix of the vagina = space in vagina above external os (a ring around it).
The posterior fornix behind forms the lowermost part of cervix, anterior fornix in front and lateral fornices.
The uterus is limited in where it can be stabilised in the pelvis from because it needs the ability to be able to extend and expand to accomodate pregnancy.
Where is the uterus stabilised?
Cervix is what is stablised.
- Pubovaginalis in the vagina indirectly stablises the uterus.
- Mainly Condensations of pelvic fascia around nerves and vessels and alone create a series of ligaments that holds the uterus in position (it holds a large weight in pregnancy).
What are the ligaments that stablise the cervix?
Series of fascial ligaments (condensations) connecting cervix to the walls of the pelvis.
- Pubocervical ligaments come forward but are the least substantial (not in diagram)
- Most significant are the lateral cervical (cardinal ligament) and are true fascial condensations around the uterine artery.
- Also rectouterine ligaments going back (also called uterosacral) going to the sacrum.
What are things that can go wrong with the positioning of the stabilsing ligaments of the cervix
Trauma of childbirth and withdrawal of oestrogen (around menopause) can cause these structures can loose their significance and strength and function. This leads to uterus and cervix starting to move out of position often also having a loss of support structure to the bladder.
- Uterus and cervix dip into the top of the vagina (type of prolapse). Severe prolapse can appear at the inferior regions of the vagina.
- Cystocele the bladder falls back into the vagina
- Rectocele with the rectum into the vagina.
Describe the formation of the broad ligament
The uterus is covered in peritoneum from above. Most of the ant. wall all of the top and all of the posterior wall is covered.
It also sweeps out to the side wall of the pelvis forming a double fold of peritoneum over the uterine tubes = broad ligament which is a double fold of peritoneum suspended from the uterine tubes. (it is not a ligament it is the peritoneum).
(it is effectively as if the uterine tubes are a curtain rod holding up a large sheet of fabric draping over either side.
Describe the parts of the uterine (fallopian) tube
- The first part of the uterine tube is within the wall of the uterus and is called intramural part
- Then the isthmus is the straight part directly lateral to that
- The ampulla is the end part that progressively widens
- The widest parts is the infundibulum
- The tubes end in fimbria (finger like projections that come out).
Ectopic pregnancies sometimes (rarely) occur in the abdominal cavity.
How could this occur?
Fimbria come out to the opening of the fallopian tube through the back of the broad ligament which is actually into the peritoneal cavity.
Uterus and uterine tubes are below (extraperitoneal) while the uterus but the broad ligament are within the peritoneal cavity (delineating it).
The ovary is stuck on the back of the broad ligament (technically in the peritoneal cavity) - so it releases the egg into the peritoneal cavity for the fallopian tubes to take and lead it extraperitoneally into the uterus.
Where is the rectum situated in the pelvic cavity?
Rectum commences at S3 extending from there down to the anorectal junction and becomes the anal canal.
Rectum sits back in the midline in the concavity of the sacrum.
The blood supply to the pelvis comes from 2 regions/sources of the body.
What is meant by this?
From Above or From The Sides
Vessels descend from the abdomen
- Eg. ovarian arteries and testicular arteries from abdominal cavity
- Also the Inferior mesenteric artery (to descending colon and sigmoid) changes its name to rectal artery and comes down to supply pelvic structures.
Vessels from the lateral walls of the pelvis: (highly variable)
- From the anterior division internal ileac artery on each side walls. Only the anterior branches gives the visceral contents (the parietal supply the walls)
Describe the nerve supply to the pelvic cavity
The bulk of visceral supply comes from a pair of inferior hypogastric plexi in the pelvis.
- Sympathetics descending from lower thoracic/upper lumbar region and parasympathetic component from the sacral plexus.
