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
superficial pouch of the perineum
potential space between the membranous layer of subcutaneous tissue and the perineal membrane; skin, fascia, tissue
deep pouch
bounded inferiorly by the perineal membrane and superiorly and laterally by the fascias to the pelvic diaphragm and obturator internus muscles
contents of superficial pouch in males
-root (crura and bulb of the penis) and associated muscles (ischiocavernosus and bulbospongiosus) maintain erection
-proximal part of spongy urethra
-superficial transverse perineal muscles
-deep perineal branches of internal pudendal vessels and pudendal nerves
contents of superficial pouch in females
-clitoris and associated muscles
-bulb of the vestibule and surrounding muscles (ischocavernosus)
-greater vestibular gland-mucous
-deep perineal branches on internal pudendal vessels and nerves
-superficial transverse perineal muscles
contents of deep pouch both sexes share
-contain part of the urethra centrally
-inferior part of the internal sphincter muscle
-anterior extension of the ischioanal fat pads
contents of deep pouch in males
-intermediate part of the urethra
-deep transverse perineal muscle
-bulbourethral glands
dorsal neurovasculature of the penis
contends of deep pouch in females
-proximal part of the urethra
-mass of smooth muscle that corresponds to the deep transverse perineal muscle
-dorsal neurovascular of the clitoris
ischioanal fascia in the anal canal
fat filled, wedge shaped region surrounding the rectum and anus
-location: anal triangle between the skin of anal region and pelvic floor
-neurovascular contents: inferior anal/rectal vessels and nerves and cutaneous branches of the sacral plexus
disruption of the perineal body
stretching or tearing of muscles from the perineal body can occur during childbirth which removes support
causes: prolapse of pelvic viscera can occur through the urethra or vaginal orifice and incontinence
