pelvis and perineum Flashcards
what is the function of the pelvis
lower limbs to spine and supports the visceral organs of the pelvis
bones of the pelvis
-2 hip bones (os coxae): fusion of the ilium, ischium, and pubis
-sacrum
-coccyx: tail bone, stabilize, can flex
divisions of the pelvis
-greater (false) pelvis: houses certain abdominal viscera
-lesser (true) pelvis: accommodates pelvic viscera, bladder, and reproductive organs
-separated by a pelvic brim
anatomical features of the pelvis:
-acetabulum: junction of the ilium, pubis, receives the femoral head
-ischial tuberosity
-obturator foramen: almost completely closed off, except for a small passage for vessels and nerves
what are differences between the male and female pelvis
-female pelvis: adapted for childbearing, lighter and shallow, wider, and provides more room in the true pelvis. sacrum is oriented posteriorly.
-male: sacrum is oriented anteriorly
ligaments of the pelvis function
hold sacrum to oxosca, prevent pelvic tilt
-weight of the trunk tends to rotate the sacrum anteriorly, resists force
what are the two ligaments of the pelvis
-sacrospinous ligament: runs horizontal
-sacrotuberous ligament: superior/inferior direction
what happens to the pelvic ligaments during pregancy
the hormone relaxin relaxes ligaments and pelvic joints, causes pelvic movement to increase
-cause: increase in pelvic rotation, transverse diameter widens allowing the passage of fetus
-problem: relaxes all ligaments and weakens the joints
pelvic diaphragm
-funnel of skeletal muscles closing the pelvic outlet
function: form a floor that supports pelvic viscera inferiorly and helps raise intraabdominal pressure, voluntary control of urination, fecal continence, and uterus support
-constantly contracts
pelvic diaphragm: muscle composition
-levator ani
-coccygeus muscles and fascia
-blood supply
-obturator internus: extra
origin of pelvic floor muscles
pelvic walls, ring
insertion of pelvic floor msucles
coccyx
female urogenital hiatus
permits passage of the urethra, vagina, and rectum
male urogenital hiatus
pelvic diaphragm permits passage of the urethra and rectum
puberectalis muscle
fecal continence: fecal continence
origin: pubis
insert: forms in and attaches to other side of pubis
innerv: ANS
pelvis blood supply:
arterial supply
-paired internal iliac arteries and branches: deliver most blood to the lesser pelvis and bifurcate into an anterior and posterior division
-pairs ovarian arteries: from aorta, not iliac
-superior rectal arteries
venous drainage of the pelvis
-drain into the internal iliac veins
-mostly internal iliac veins and their branches
-superior rectal veins (portal venous system)
-gonadal veins
innervation of the pelvis
-sacral (S1-S4) and coccygeal spinal nerves and pelvic part of the ANS
-lumbosacral trunk: sciatic nerve
-pudendal nerve: main nerve of the perineum and chief accessory nerve of the external genitalia. S2-S4
-superior and inferior gluteal nerves: branches from lumbar and sacral plexus, go backwards
-coccygeal plexus: small network of nerve fibers formed by the ventral rami of S4 and S5
pudendal canal
horizontal passageway within the obturator fascia which covers the medial aspect of obturator internus; transmits the internal pudendal vessels and pudendal nerve supply the perineum
pudendal nerve
somatic innervation S2-S4 to perineal body wall, muscles, genitalia, external anal sphincter and skin of perineum; also carries sympathetic
-runs through the pelvis-sacrospinous ligament-out and under-along ischium-external genitalia
perineum
diamond shaped pelvic outlet that lies inferior to the pelvic aperture
what is the perineum bounded by
by the pubic symphysis anteriorly, ischial tuberosities laterally, and coccyx posteriorly.
what is the perineum subdivided
-urogenital (UG) triangle: root of scrotum, penis, and vulva
-anal triangle anal canal and anus
what muscles is the perineum bounded by
superiorly by levator ani and laterally by obturator internus
