Ach: Lower Abdominal Cavity I Flashcards
What forms the pelvic brim?
- sacral promontory and ala
- pectineal line
- symphysis pubis
What forms the false pelvis?
part of the abdominal cavity that supports abdominal organs
What forms the true pelvis?
- Pelvic inlet
- pelvic outlet (coccyx, ischial tuberosities, pubic arch)
- pelvic cavity (space between inlet and outlet)
What forms the sacrococcygeal joint?
cartilagenous intervertebral joint (S5-C1)
What forms the symphysis pubis?
fibrocartilagenous joint between bodies of two pubic bones
What forms the lumbosacral joint?
typical cartilagenous intervertebral joint between L5-S1
What forms the sacroiliac joint?
synovial joint between articular surfaces of ilium and sacrum
What is the interosseous sacroiliac ligament?
Suspends sacrum between two iliac bones
transfers weight from axial to appendicular skeleton
Resists forward rotation of the upper sacrum
What is the difference between the posterior and anterior sacroiliac ligaments?
Anterior = thin, not well defined
posterior= 2 parts, very strong
What forms the sacrotuberous ligament?
from the ischial tuberosity to lower sacrum and coccyx
What does hte sacrotuberous ligament do?
resists backward rotation of the lower sacrum
Where is the sacrospinous ligament?
It extends from the ischial spine to the lower sacrum and coccyx
What does the sacrospinous ligament do?
resists backward rotation of the lower sacrum
What is the difference between the pelvises of males and females?
M- heavy, thick, more prominent bone markings,
F- wider, shallower, larger superior and inferior pelvic apertures, ROUNDER and WIDER pubic arch
pelvic inlet is heart shaped in M but OVAL in F
Antrhopoid pelvis
ape like 23%
platypelloid pelvis
flat 2%
android pelvis
M 32%
gynecoid pelvis
F 43%
What can cause dystocia (difficult labor)?
deformities of the pelvis
What is the true conjugate diameter?
Sacral promontory to point just below the superior margin of the pubic symphysis (11 cm)
The shortest diameter through which the head must pass (radiographic films)
What is the diagonal conjugate?
sacral promontory to lower border of pubic symphysis (11.5 cm) (easily measured and assessed)
What is the obstetric conjugate?
sacral promontory to thickest part of pubic bone (10 cm)
What forms the pelvic walls?
- obturator internus
2. piriformis
What forms the pelvic floor? What does it support?
The pelvic diaphgram
supports the pelvic viscera
Where is the pelvic diaphragm located?
Stretches across the pelvis like a hammock
Suspended from the iliacus fascia
Divides the cavity into the pelvis above and the perineum below
What are the two divisions of the pelvic diaphgragm?
- levator ani (anterior)
2. coccygeus (posterior)
What are the actions of the pelvic diaphragm
Support pelvic floor and organs that pierce it
Resists outward thrust accompanying increases in intra-abdominal pressure (forced expiration and coughing)
Assists in defecation
The female pelvis contains what internal reproductive organs?
ovaries
uterine tubes
uterus
vagina
Where are the vagina and uterus located?
midsagittally
Where are the bladder and rectum located?
midline structures (both sexes)
What is the endopelvic fascia?
in the pelvis covers and supports the pelvic viscera, fills in spaces, and transmits neurovasculature to the organs; it is continuous with the fascia transversalis in the abdomen;
What are the two components of the endopelvic fascia?
- parietal pelvic fascia (forms sheath over pelvic muscles)
2. visceral pelvic fascia (forms fascial coverings over pelvic viscera)
What fascia is important for the repair of prolapsed structures (more than muscles)?
endopelvic fascia
The visceral pelvic fascia is thickened to form what ligaments?
Cardinal ligaments
sacrouterine ligaments
In a mid-saggital section how is the peritoneum traced?
anterior abdominal wall
superior surface of urinary bladder
vesicouterine pouch (uterovesical) anterior and posterior uterus upper portion of vagina and rectouterine pouch (of Douglas) anterior surface of rectum continuous with sigmoid mesocolon
What separates the anterior surface of the uterus from the urinary bladder?
vesicouterine pouch
What separates the posterior surface from the rectum?
rectourterine pouch
What is the broad ligament of the uterus?
2 layered fold of peritoneum that extends across the pelvic cavity from the uterus to the lateral pelvic walls
What are the parts of the broad ligaments?
- Mesovarium
- Suspensory ligament
- Mesosalpinx
- Mesometrium
What does the mesovarium do?
Attaches the ovary to the posterior layer of the broad ligament
What does hte suspensory ligament do?
transmits the ovarian vessels, lymphatics and nerves that the ovary dragged in its descent from the abdomen
lies lateral to the attachment of the mesovarium
Each uterine tube occupies the free superior margin of the broad ligament in the…
mesosalpinx
What is the mesometrium?
portion of the broad ligament below the mesosalpinx and mesovarium
What is the round ligament of the ovary?
Upper remnant of the gubernaculum
Extends from the ovary to the uterus where the uterine tube connects
What is the round ligament of the uterus?
Passes from the uterus to the deep inguinal ring and through the inguinal canal (lower remnant of the gubernaculum)
What causes prolapse of the uterus?
laxity or atonia of the muscles of the fascia nad pelvic floor
What causes prolapse of the uterus?
Obstetrical trauma
Damage to pelvic floor:
laceration of the perineum
separation of the levator ani muscle
What causes bladder prolapse?
Repeated obstetrical trauma can cause the inferior portion of the bladder to sag below the openings of the urethra d/t a weakened or torn pelvic diaphragm to form a cystocele
What causes prolapse of the rectum?
incompetent pelvic diaphragm (anterior wall of rectum bulges into the vagina)
What reproductive organs does the male pelvis contain?
ductus deferens seminal vesicles ejaculatory ducts prostate gland urethra
What is the only pouch in males?
rectovesical pouch
What types of nerves does the sacral plexus contain?
somatic nerves
What contributes to the sacral plexus?
- lumbosacral trunk (half of L4, L5)
2. Ventral rami of S1-S4
All the branches of the sacral plexus pass through the greater sciatic foramen except which nerve which exits below the piriformis muscle?
Superior gluteal nerve
Sciatic nerve
L4, 5, S1-3
Superior gluteal nerve (nerve to the quadratus femoris)
L4, 5, S1
Inferior gluteal nerve (nerve to the obturator internus)
L5, S1-2
posterior femoral cutaneous nerve
S1,2,3
pudendal nerve
S2,3,4
What branches supply the piriformis?
S1,2
What branches of the sacral plexus supply the levator ani?
S3,4
What supplies autonomic innervation to ALL of the pelvic organs EXCEPT the gonads?
inferior hypogastric plexus
Superior hypogastric plexus > right and left hypogastric nerves (1-4) which descend on the sacrum via the inferior hypogastric plexus
Where is the inferior hypogastric plexus located?
extraperitoneal tissues of the pararectal fossae
Describe the sympathetic component of the inferior hypogastric plexus.
Preganglionic neurons (lower thoracic and upper lumbar levels of the spinal cord)>
- lumbar splanchnics–> synapse on small clusters of POSTgang neurons in the inferior hypogastric plexus
- sacral splanchnics–> descend in the lumbar and sacral sympathetic trunk WITHOUT synapsing and enter the inferior hypogastric plexus to synapse on clusters of postgang neurons
What does the sympathetic component of the inferior hypogastric plexus do?
inhibits contraction of the wall of the rectum and bladder
What does the parasympathetic component of the inferior hypogastric plexus do?
contracts the bladder and rectum
relaxes the internal sphincters of the rectum and bladder
Describe the parasympathetic component of the inferior hypogastric plexus.
Pregang neurons to the IHP have nerve cell bodies in S2,3,4>
leave as pelvic splanchnic nerves>
enter IHP but DONT synapse>
terminate on post gang neurons in the walls of the organs innervated
Visceral afferent fibers in the IHP sense…
pain and distension
What subsidary plexuses does the IHP give rise to?
rectal
prostatic
uterovaginal
vesical
all follow branches of hte internal iliac artery