Perineum III Flashcards
The linea terminalis consists of what?
of a line that circumscribes the sacral promontory (S1 vertebra), the arcuate lines of the ilium, the pectinal lines of the pubis and the pubic symphysis.The linea terminalis marks the inlet of the true pelvis (a.k.a. the pelvic brim or the superior pelvic aperture).
The pelvic outlet (aka inferior pelvic aperture) is bounded by what?
bounded by the inferior margin of the pubic symphysis, inferior pubic rami, sacrotuberous ligaments and tip of the coccyx.
The division between the false (or greater) pelvis and the true (or lesser) pelvis is what?
linea terminalis
The false pelvis consists primarily of what?
loops of intestines
the true pelvis consists primarily of what?
elements of the urinary, gastrointestinal, and reproductive systems and their neurovascular supply.
What are some important gender differences between the bony aspects of the male and female pelvis?
In the female:• The pelvic inlet is circular.• The angle of the pubic arch is wider (80‐85 degrees)• The ischial spines don’t project as far into the pelvic cavity• The bones of the pelvic girdle are thinner and less massiveIn the male:• The pelvic inlet is heart shaped• The angle of the pubic arch is narrower (50‐60 degrees)• The ischial spine project more prominently into the pelvic cavity• The pelvic bones are thicker and more massive
The True (or Obstetrical) conjugate refers to what?
refers to the minimum anterior to posterior diameter of the lesser pelvis as measured between the sacral promontory and the superior margin of the pubic symphysis. This is the narrowest fixed distance that the baby’s head must pass thru during a vaginal delivery. However, this distance cannot be measured directly during a pelvic exam due to the presence of the bladder.
What is the diagonal conjugate?
is measured manually during the pelvic exam by palpating the sacral promontory with the tip of the middle finger while using the other hand to mark the level of the inferior margin of the pubic symphysis on the examining hand.The true conjugate is then estimated as the distance between the tip of the index finger (not the middle finger) and the marked level of the pubic symphysis.
The estimated true conjugate distance should be __ cm or greater to ensure safe delivery
11
What is the interspinous distance in relation to pelvimetry?
the narrowest part of the pelvic canal from side to side as measured between the right and left ischial spinesDuring the pelvic exam, if the ischial tuberosities are far enough apart to allow three fingers to enter the vagina side‐by‐side, it is considered sufficiently wide to permit safe delivery
What are the two muscles of the pelvic diaphragm?
the levator ani and the coccygeus
What is the innervation of the levator ani?
inferior rectal n. and direct branches from S4
What is the innervation of coccygeus?
direct branches from S3 and S4
The only physical barrier between the abdominal cavity above and the pelvic cavity below is what?
is the inferior extent of the parietal peritoneum.The peritoneum drapes over the pelvic viscera, covering or enveloping the pelvic viscera and also forming pouches or spaces between adjacent viscera and a number of folds or ligaments between viscera and the pelvic walls. It generally does not reach all the way to the pelvic floor.
In the male, the draping of the peritoneum between the bladder and the rectum forms?
the rectovesical pouch
The pouch in women formed between the bladder and the anterior wall of the uterus is called what?
the vesicouterine pouch
What is formed between the posterior wall of the uterus and the rectum?
The rectouterine pouch (Pouch of Douglas)
What is the clinical significance of Douglas’ pouch?
The Pouch of Douglas is the lowest point of the abdominopelvic cavity when the patient is in the supine position. It is a frequent collection site for fluids and infection. It is also at risk for perforation during cystoscopic procedures that use a vaginal approach due to the proximity of the posterior fornix of the vagina. It’s also the most common site for abdominal ectopic pregnancy.
In the most posterior position, the pelvic parts of the gastrointestinal system include what?
the terminal end of the sigmoid colon, the rectum and the anal canal.
The rectum is continuous with the sigmoid colon at about the level of?
SV3. The rectum is the most posterior element of the pelvic viscera and lies on the anterior surface of the sacrum.
T or F. the rectum is maintained entirely in the pelvis
T
The lower part of the rectum is expanded to form the?
rectal ampulla
What does the rectal ampulla do?
The ampulla is capable of a fair amount of distension and serves as a reservoir for fecal matter. This is one contribution to our ability to maintain fecal continence.
Where does the anal canal begin?
at the terminal end of the rectal ampulla where it narrows at the pelvic floor.
The anal canal begins in the perineum at a 90 degree angle to the rectal ampulla. What is this transitional point called?
perineal flexure
What maintains the 90 degree angle between the rectum and the proximal anal canal?
the puborectalis part of levator ani (is relaxed during defecation)
The anal canal is surrounded on along its entire length by what?
the internal (involuntary) and external (voluntary) anal sphincters which normally keep it closed.
The upper part of the canal is lined by mucosa similar to the mucosa lining the rectum and is distinguished by longitudinally oriented folds called?
anal columns
The anal columns overlie what?
the terminal branches of the superior rectal veins
The distal ‘end’ of anal columns are called what?
anal valves which overlie communicating veins
The upper border of the anal columns marks what?
the transition from the rectal ampulla to the anal canal i.e. the ano‐rectal junction.
An imaginary line connecting the anal valves denotes the ___ which marks what?
pectinate line which marks the approximate position of the anal membrane in the embryo.
Inferior to the pectinate line is a transition zone known as the anal pecten which is lined by what kind of epithelium?
non‐ keratinized stratified squamous epithelium.
Inferior to the anal pectan is what?
The white line (anocutaneous line), marking the change from the cutaneous zone to the transitional zone. Below this line is pigmented, hair bearing skin containing glands.
What five transitions occur at the pectinate line in the anal canal?
Mucosa:Above—Endoderm Below—EctodermInnervation:Above—Visceral (autonomic) motor and sensory innervation via the inferior hypogastric plexus. This portion of the anal canal is not sensitive to pain, temperature, touch.Below—Somatic motor and sensory innervation via the inferior rectal nerves. This portion of the anal canal is sensitive to pain, temperature, touch.Blood Supply:Above—Arterial supply is from the superior rectal arteries and venous drainage is to the portal system via the superior rectal veins (IMV).Below—Arterial supply is from the middle and inferior rectal arteries and venous drainage is to the caval system via the middle and inferior rectal veins (Internal Iliac Vein).Hemorrhoids:Above—Internal hemorrhoids, related to internal venous plexus, not painfulBelow—External hemorrhoids, related to external venous plexus, very painfulWith internal hemorrhoids, one must consider the possibility of portal hypertension/liver occlusion.Lymphatic Drainage:Above—Drainage is to the internal iliac nodes Below—Drainage is to the superficial inguinal nodes
The pelvic parts of the urinary system consists of what?
the terminal parts of the ureters, the bladder and proximal part of the urethra
The apex of the bladder is continuous with what?
the median umbilical ligament (urachus) on the anterior abdominal wall (remnant of the allantois from embryology).
What is the most ‘fixed’ part of the bladder?
the neck
The bladder is immediately superior to what in males?
the prostate gland
What fixes the neck of the bladder?
the pubovesical/puboprostatic ligaments and the attachments of the urethra to the prostrate gland (males) or urogenital/pelvic diaphragms (females)
Where do the pubovesical/puboprostatic ligaments come from?
thickenings of the visceral pelvic fascia
What is the potential space between the apex of the bladder and the pubic bones called?
the retropubic space (of Retzius). This space is useful in retrieving a urine sample via cystoscope.
Where do the ureters enter the bladder?
the superior angles of the trigone
The walls of the bladder external to the trigone area are primarily comprised of detrusor muscleThe walls of the bladder external to the trigone area are primarily comprised of what?
detrusor muscle. The detrusor (comprised of smooth muscle) relaxes to allow the bladder to fill and contracts to allow the bladder empty.
The muscle fibers at the distal end of the trigone form what?
the internal urethral sphincter muscle. The internal urethral sphincter contracts to keep the internal urethral orifice closed as the bladder fills with urine. It relaxes to allow the bladder to empty.
What is the detrusor muscle innervated by?
parasympathetic fibers via the pelvic splanchnic nerves (S2‐4)
What is the internal urethra sphincter muscle innervated by?
sympathetic fibers via the lumbar splanchnic nerves (L2‐4)
What is the ureter crossed by superiorly on the lateral wall of the pelvis in males?
ductus deferens
What wraps around the ureter in women?
the uterine artery
What are the three potential constriction sites of the ureter?
at the pelvic brim, in the bladder wall and at the junction of the ureter with the renal pelvis. These are sites where kidney stones can lodge and block flow of urine.
Describe the route of the urethra in women
The urethra is short (~3‐4 cm) and travels a direct, inferior route to terminate externally in the vestibule of the vagina. It passes thru the pelvic diaphragm, UG diaphragm and superficial compartment of the perineum to open in the vestibule at the external urethral orifice.
Describe the route of the urethra in men
The urethra is longer (~ 20 cm) and takes a more complex route through the pelvis and perineum. It passes inferiorly thru the prostate gland, UG diaphragm and enters the root of the penis via the bulb of the penis and continues distally in the corpus spongiosum. It opens at the external urethral orifice at the tip of the penis.
What are the 2 angles in the course of the male urethra?
- There is a fixed angle where the urethra bends anteriorly in the root of the penis after passing thru the UG diaphragm.2. There is another angle distally where the unattached part of the penis curves inferiorly when the penis is flaccid. Note that this angle disappears when the penis is erect.These are important considerations that must be taken into account when catheterizing a male patient.
What three structures open into the prostatic urethra in the male?
Ejaculatory ducts, prostatic ducts and the prostatic utricle.
The lumen of the prostatic urethra is marked by a longitudinal midline fold of mucosa called the
urethral crest
The depressions on either side of the urethral crest in the prosaic urethra are what?
the prostatic sinuses
What happens at the prostatic sinuses?
the ducts of the prostate gland empty into these sinuses.
Midway along its length, the urethral crest is enlarged to form a circular elevation called the
the seminal colliculus
What is contained in the seminal colliculus?
The prostatic utricle opens onto the center of the seminal colliculus. On each side are the openings of the ejaculatory ducts.Looks like upside down bowling ball finger holes
What part of the urethra are the bulbourethral glands (Cowper’s) found?
in the penile urethra
Where are the female external genitalia found? What does this consist of?
in the superficial space of the perineum and consist of the mons pubis, labia majora, labia minora, vestibule, clitoris, distal portion of the vaginal canal and the greater vestibular (a.k.a. Bartholin’s) glands. These are collectively referred to as the vulva
Where are the female internal genitalia found? What does this consist of?
in the true pelvis and consist of the ovaries, the uterine tubes, the uterus and the proximal portion of the vaginal canal.
What are the three components of the broad ligament?
mesometrium, mesosalpinx, and the mesovariumthe broad ligament is a sheet like fold (mesentery) of peritoneum with anterior and posterior layers that enclose the uterus, ovary and uterine tubes.
Where does the mesometrium span?
extends from the lateral pelvic walls to the body of the uterus
Where does the mesosalpinx span?
most superior part of the broad ligament, suspends the uterine tube in the pelviccavity
Where does the mesovarium span?
horizontally from the broad ligament to suspend the ovaries posterior to the uterus
What is the suspensory ligament of the ovary?
a superior extension of the mesovarium
Enclosed within the two layers of the broad ligament is what?
the round ligament and ligament of theovary.
The uterus is enveloped in what part of the broad ligament?
mesometrium
Structurally, the uterus consists of what parts?
the fundus, body, isthmus, uterine cavity and cervix
Where is the fundus of the uterus?
the part of the uterus above a line connecting the uterine tubes
What are the body and isthmus of the uterus?
The body is the part of the uterus between the fundus and the cervix. The isthmus is the part of the body that narrows inferiorly into the cervix.
What is the cervix continuous with? What connects these two?
the vaginal canal. The cervical canal connects the uterine cavity and the vagina
What are the components of the cervical canal?
The uterine opening of the canal is the internal os. The vaginal opening of the canal is the external os.NOTE: The cervix may be divided into two parts, supravaginal and infravaginal. Note that the infravaginal portion projects inferiorly into the lumen of the vaginal canal, forming the anterior, posterior and lateral fornices of the vaginal canal.
Describe how the uterus typically sits in relation to the bladder.
The uterus normally arches superiorly forward over the superior surface of the emptied bladder. In addition, the cervix is angled forward on the vagina so that the inferior end of the cervix projects toward the posterior wall of the vagina. In this position, the uterus is said to be anteverted and anteflexed.
What is the angle of anteflexion?
refers to the angulation between the axis of the cervix and the axis of the body of the uterus
What is the angle of anteversion?
to the angulation between the axis of the cervix and the axis of the vaginal canal (~100‐110 degrees)
What is prolapse of the uterus?
occurs when the support structures of the uterus are damaged. Uterine prolapses are classified as first, second or third degree depending upon the extent of the uterine protrusion. Prolapse is often a consequence of trauma during childbirth, an improperly positioned uterus or due to the normal process of aging. Uterine prolapse may be treated surgically or by the use of a prosthetic device called a pessary.
What helps support the positioning and structure of the internal female genitalia?
the bladder and the rectum, the pelvic and urogenital diaphragms, the perineal body and the transverse cervical (cardinal), pubovesical, uterosacral and round ligaments
The ovaries are projected posteriorly relative to the uterus by what?
mesovarium of the broad ligament
Each ovary is suspended from the uterus by?
the ovarian ligament which attaches to the inferior pole
The superior pole of each ovary is suspended from the lateral wall of the pelvis by what?
the suspensory ligament of the ovary
What does the suspensory ligament of the ovary convey?
The suspensory ligament of the ovary transmits the ovarian artery, vein and nerve supply.
The ovary lies in the ovarian fossa. Where is this?
The ovarian fossa is a slight depression in the peritoneum that is bounded by the ureter posteromedially and the external iliac vessels anterolaterally
The uterine tubes are suspended in the ___ of the broad ligament and project laterally from the body of the uterus,
mesosalpinx
T or F. the uterine tubes arch superiorly and posteriorly to open into the peritoneal cavity immediately adjacent to the ovaries
T
The expanded end of a uterine tube is called what?
the infundibulum (which curves around the superior pole of the ovary)
The margin of the infundibulum is rimmed with small fingerlike projections called what?
fimbriae. The movements of the fimbriae are useful in trapping the ovum and sweeping it in toward the opening of the uterine tube
Where does conception usually occur?
the ampulla of the uterine tube, just medial to the fimbriae
The ampulla then narrows to form the ___ of the uterine tube before joining with the body of the uterus just inferior to the fundus of the uterus.
isthmus NOTE: From a clinical perspective, the uterine tubes are common sites for ectopic (or non‐uterine) pregnancy and must be carefully examined when an ectopic pregnancy is suspected. The uterine tube will rupture resulting in an abdominopelvic hemorrhage if the ectopic pregnancy is not terminated.
What is Tubal ligation?
a surgical method of birth control that is commonly used by women looking for a permanent method of contraception
The blood supply to the vagina is primarily via what?
the vaginal arteries.An anastomosis with the uterine artery also helps to supply the vagina with oxygenated blood.
Where do the vaginal arteries come from?
normally arise as branches of the internal iliac artery.
What drains the vagina?
the pelvic plexus of veins
culdoscopy (sampling pelvic fluids) is often performed via what?
the rectouterine pouchThis must be performed under carefully controlled and sterile conditions in order to avoid the introduction of bacteria into the sterile environment of the abdominopelvic cavity. This procedure has largely been replaced by laparoscopic procedures in recent years. NOTE: care should be taken when inserting an instrument into the vagina. Insertion of the speculum with too much force may cause a rupture of the vaginal fornices and exposure of the abdominopelvic cavity to bacterial infection
