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