anatomy of the female pelvis Flashcards
what is mons pubis
pad of fatty tissues that overlies the pubis
What are some external landmarks?
vagina mons pubis labia clitoris urethral opening anus
What is the True Pelvis?
Below plevic brim to the pelvic diaphragm, contains pelvic organs
what is the false pelvis?
above the pelvic brim to the iliac crest - communicates with abdominal cavity superiorly
pelvic cavity
true pelvis, inferior to the caudal portion of the parietal peritoneum
what is in the posterior pelvic cavity
rectum, colon and ileum
what is in the anterior pelvic cavity
bladder, ureters, ovaries Fallopian tubes, uterus and vagina
what is the pouch of douglas
rectouterine space - lowest most posterior portion of the peritoneal cavity
what forms the posterior wall?
sacrum and coccyx
margin of post-lat wall formed by piriformis and coccygeus muscles
what forms the anterolateral walls?
formed by hip bones and obturator internus muscles
what forms the lower margin pelvic cavity?
(aka pelvic floor or pelvic diaphragm)
formed by levator ani and coccygeus muscles
muscles of the false pelvis
psoas major muscles - originate at the transverse process of lumbar vertebrae - descend inferiorly on pelvic side walls- join iliacus muscles in false pelvis (they do not enter the true pelvis)
lliopsoas muscle, iliacus and psoas major muscles: descend anterior to hip-insert into lesser trochanter, pass outside pelvic bones , do not enter true pelvis
what are the muscles of the true pelvis?
Piriformis muscles -
Obturator internus muscles -
pelvic diaphragm -
levator ani muscle (3 muscle groups) Puboccygeus muscles, lliococcygeus muscles, puborectalis (see the slide)
Bladder
location: anterior portion pelvic cavity - posterior to pubic symphysis
Function: Collect and store urine
remains in true pelvis when empty
when distended rises behind lower anterior abdominal wall pushes peritoneum away
vagina
extends postero-superiorly at a 45 degree angle from external genitalia to cervix, then forms a 90 degree angle to the cervix
average 9 cm long
anterior to rectum/anus - posterior to bladder/urethra
mucus membrane lining muscular walls
passageway for the products of menstruation
easily distended during sexual intercourse and childbirth
posterior wall is longer than the anterior wall
mucus membrane lining muscular walls
upper half above pelvic floor, lower hald within perineum
arterial supply - vaginal and uterine arteries drain into interal iliac veins
upper portion attaches to cervix -posterior portion attaches higher on cervix
what are the fornices?
4 arch like recesses formed by cervix protruding into upper portion of vaginal canal
blind pockets formed by inner surface of vagina and outer surface of cervix
continuous ring shaped space
uterus
Müllerian ducts enlogate and fuse to form uterus and vagina between 7th and 12th week of gestation
posterior to bladder/anterior to rectum
hollow, pear shaped
largest organ of female pelvis - allows for cyclic physiologic changes assoc with menstruation and after fertilization, serves to sustain, protect and deliver fetus
3 parts: fundus, body, cervix
usually antiflexed and antverted (held in place by round ligaments)
average size 6-8 cm long and 3-5 cm AP and transverse varies with age and parity
supported by levator ani muscles, cardinal ligaments and uter-sacral ligaments
portions of uterus
cervix isthmus body of uterus fundus of uterus cornua
what is the cervix?
"neck of uterus" lower cylindrical portion of uterus - projects into vaginal canal muscular divided into exocervix and endocervix only portion of uterus firmly supported
ithmus
ourter transition point between body of uterus and cervix
“waist” of uterus
point where uterus bends with empty bladder
anteversion bends anteriorly
retroversion bends posteriorly
uterine blood vessels enter at this point
body of uterus
aka corpus
between fundus and cervix
largest portion of the uterus
cavity funnel shaped coronal plane, slit-like sagittal plane
potential space for fluid accumulation-dynamic changes during menstrual cycle and pregancy
posterior to vesicouterine pouch and superior surface of bladder
anterior to rectouterine pouch ( pouch of douglas), ilium and colon
walls are together unless something is in there to separate them
fundus of uterus
widest portion of uterus
uppermost cephalic poriton of uterus
dome shaped
cornua - lateral borders of fundus, Fallopian tubes enter uterine cavity, interstitial portion of Fallopian tubes
layers of the uterine wall
3 histologic layers
perimetrium - serosa - outermost peritoneal covering (external layer)
myometrium - middle layer -muscular- thickest layer- primarily smooth muscle that is longitudinal and circular. contains main branches of uterine vessels and nerves
endometrium - inner layer - glandular tissue lining - mucous membrane - 2 layers which undergo monthly hormonal changes
endometrium
continuous with cervical canal - endocervical canal
changes dynamically responding to the cyclic hormonal changes. Appearance varies depedning on the patients menstrual status and period of life
two layers- zona funtionalis and zona basalis
zona funtionalis
superficial layer of glands and stroma (supporting tissue)
sheds with menses
zone basalis
basal layer
layer of endometrial glands which regenerate new endometrium after menses
uterine ligaments
anchor uterus in proper position in midline of pelvis
broad ligaments
round ligaments
uterosacral ligaments
cardinal ligaments
broad ligaments
double fold of peritoneum drapes over uterus, ovaries Fallopian tubes
lateral aspect of uterus to sidewalls of pelvis - provides lateral support for the uterus
covers both anterior and posterior surfaces of uterus
contain uterine vessels and nerves
3 separate areas: mesometrium, mesosalpinx and mesovarium
mesometrium
portion of broad ligament over the uterus
mesosalpinx
portion of broad ligament - upper fold encloses Fallopian tubes
mesovarium
posterior portion of the borad ligament that encloses the ovaries
round ligaments
hold fundus and body in forward position (anterior support)
attach to anterior lateral portion of fundus, extend to inguinal canal
insert into labia majora
holds uterine fundus in normal anteflexed position
uterosacral ligaments
attach posterior-lateral aspect of uterus at level of internal cervical os
extend posteriorly and inferiorly to sacrum
support cervix
with round ligaments hold uterus in normal anteflexed position
cardinal ligaments
aka: transverse cervical ligaments, mackenrodt ligaments or parametrium
provide lateral support of cervix and lower uterine segment
continuation of broad ligaments which extend across pelvic floor laterally from isthmus/cervix to pelvic sidewalls
with uterosacral ligaments hold cervix in fixed position
important landmarks for surgery - contain uterine vessels
explain the support system in the pelvis
explain which muscles and ligaments and where on the bone they attach
positions of the uterus
variable
most common anteverted/anteflexed
full bladder will tip average uterus backward
anteversion
anteflexion
retroversion
retroflexion
retroverted/retroflexed
dextroversion dextroflexion levoversion levoflexion uterine prolapse
anteversion
cervical canal forms 90 degree or smaller angle with vaginal canal anteriorly
anteflexion
fundas and body curved forward on cervix
approx 170 degree angle between uterine /cervical canal
retroversion
cervical canal forms > 90 degrees angle with vaginal canal (entire uterus tips posteriorly)
retroflexion
fundus and or body curved backward on cervix
two angles (version/flexion) are independent of each other - uterus can be in any combination of version and flexion
dextroversion
entire uterus/cervix tilts to the right
dextroflexion
uterine body at isthmus bends to the right
levoversion
entire uterus/cervix tilts to the left
levoflexion
uterine body at isthmus bends to the left
uterine prolapse
abnormal dropping of the uterus- uterine and pelvic floor muscles weak and allow uterus to protrude into the vagina
pelvic spaces
cul-de-sacs or gutters- potential spaces where fluid can accumulate
vesicouterine space
anterior cul-de-sac between bladder and fundus of uterus
rectouterine space
aka: “pouch of douglas”
posterior cul-de-sac between uterus and rectum
most inferior and posterior region of the peritoneal cavity
space of retzuis (reezts e us)
between symphysis pubis and anterior bladder wall
usually contains subcutaneous fat
hematoma or abscess may displace urinary bladder posteriorly
Fallopian tubes
also called oviducts or salpinx
coiled muscular tubes
normal length 7-12 cm in length, 1-4 mm in diameter
picks up egg released by ovary transports egg to endometrial cavity through peristaltic contractions of the muscle walls
innermost region-mucosal layer runs directly into endometrium
not able to visualize on US if normal
may use Doppler to distinguish between blood vessels and dilated tube
4 segments: interstitial, isthmus, ampulla, and infundibulum
Fallopian tube : interstitial portion
intramural
narrowest segment
passes through uterine cornua
connects to endometrial cavity
approx 1 cm long
ovaries
solid “almond shaped” structures
lie in ovarian fossa (waldeyer’s fossa)
normal position: posterior-lateral to cornua, medial to external iliac vessels, anterior to internal iliac vessels and ureters
vary in size during lifespan depending on hormonal status
Fallopian tube + Ovary = ADNEXA
ovary blood supply
ARTERIAL:
dual blood supply
arterial blood via gonadal arteries from aorta
ovarian arteries arise in distal aorta-distal to renal arteries
ovarian arteries anastamose with uterine artery in broad ligament
ovarian branch of uterine artery continues to feed ovary
VENOUS DRAINAGE:
right ovarian vein drains directly into IVC
Left ovarian vein drains into Left renal vein
ovarian size
average ovarian length in menarcheal female 3.0 cm
size dependent on menstrual/hormonal status (menarcheal 2.5-5.0cm in length, 1.5-3.0 cm in width and height)
volume (L x W x H x 0.523) know this formula)
pre-puberty: up to 8 cc
Mernarcheal: up to 18cc (usually 6-10 cc) (3.0x2.0x2.0cm x 0.523)
Post- menopausal: up to 8cc (usually 5.8 cc) (2.0x0.5x1.0cm x 0.523)
what are the different positions of the ovaries?
for scanning purposes not for test…
ovaries are mobile and may change in position based on pregnancy, ligament laxity, previous surgeries/pathology, uterine position and bladder filling
May Lie:
anterior to the internal iliac vessels
medial to the external iliac vessels
from the posterior cul-de-sac to the lower abdomen
orientation may be vertical, horizontal or anywhere in between
normal anatomy for ovary
cortex -
medulla -
ovum -
hormones -
estrogen and progesterone
hormones produced by ovaries
responsible for producing and maintaining secondary gender characteristics, preparing uterus for implantation and development of mammary glands
estrogen: secreted by follicles
Progesterone: secreted by corpus luteum
ovarian ligaments
ovarian ligament
suspensory ligament -
mesovarian ligament -
Pelvic Vasculature
Ao to common iliac arteries (ant and med to psoas muscles)
Common iliac arteries - external and internal iliac (hypogastric) arteries
uterine Artery -
arcuate arteries -
radial arteries (branches of arcuate arteries)
straight and spiral arteries
explain the blood supply to the pelvis and it’s structures
finish
venus flow is the same as arterial just backwards
what makes up the bony pelvis?
two compartments divided by iliopectineal line - superior border of sacrum to superior margin of pubis symphysis
false pelvis
true pelvis
pelvic brim - corresponds with iliopectineal line and sacral promontory
what bones make up the bony pelvis?
from the right of the spine: posterior superior iliac spine iliac crest tubercle of crest anterior superior iliac spine acetabulum ischial tuberosity ischiopubic ramus pubic symphysis obturator foramen lesser sciatic notch ischial spine greater sciatic notch posterior sacral foramen sacrum coccyx
where is the perineum?
It the area below pelvic floor
where is the piriformis muscles?
posterolateral wall
triangular, flat muscles
anterior sacrum through greater sciatic notch
inserts to superior aspect of greater trochanter of femur
posterior to rectum, vagina and uterus
where are the obturator internus muscles?
anterolateral wall
trianglular sheets of muscles
anterolateral pelvic wall
surround obturator foramen
through lesser sciatic notch
inserts to superior aspect of greater trochanter
lateral at the level of the transverse cerix
what is the pelvic diaphragm?
floor of the true pelvis
formed by levator ani and coccygeus muscles
levator ani muscles
3 muscle groups
role in rectal and urinary continence
forms anterior part of diaphragm
forms “hammock” to support rectum and pelvic floor
major supporting structure for pelvic structures
puboccygeus muscles
most anterior and medial
pubic bones to coccyx
surround urethra, vagina and rectum
iliococcygeus muscles
anterolateral pelvic wall to coccyx
puborectalis muscles
lower part of pubic symphysis
surround lower part of rectum
form sling
what are ureters?
ureters- tubes from kidneys to trigone of bladder. anterior to the internal iliac arteries. posterior to ovaries and uterine arteries. ‘jets” in the posteriorinferior portion of the bladder with color doppler.
what are the layers of the uterus?
perimetrium
myometrium
endometrium
what is premenarchal uterine size?
length: 1.0-3.0 cm
width: 0.5-1.0cm
AP cm: 0.5-1.0
volume: n/a
Cervix/corpus ratio: 1/2 : 1/2
what is the uterine size for menarchal nulliparous?
length: 6.0-8.0 cm
width: 3.0-5.0 cm
AP cm: 3.0-5.0
volume cc: 30-40
cervix/corpus ratio: 1/3 : 2/3
what is the uterine size for menarchal parous?
Length: 8.0-10.0cm width: 5.0-6.0cm AP cm: 5.0-6.0 volume cc: 60-80 cervix/corpus ratio 1/3 :>2/3
what is the uterine size of postmenopausal?
length: 3.0-5.0cm
width: 2.0-3.0cm
AP cm: 2.0-3.0
volume cc:14-17
cervix/corpus ratio: 2/3 :1/3
what is the exocervix?
squamous epithelium
continuous with the vagina
what is the endocervix?
cervical canal
columnar cells, excrete mucus
constricted at upper end by internal os - communicates to uterine cavity
constricted at lower end by external os - communicates to vagina
retroverted/retroflexed uterus
uterus tipped and flexed backward…a common varient
Fallopian tube : isthmus
medial portion between interstitial portion and ampulla
increases in diameter as it extends towards ampulla
thick muscular wall
approx. 2cm long
Fallopian Tube: ampulla
longest
most coiled portion
area where fertilization of the ovum usually occurs
most distensible region of tube
approx 5 cm long
Fallopian Tube: infunibulum
Wide, trumpet shaped, lateral portion
fimbriae - fringe like structures - extend toward ovary (direct ovum into the Fallopian tube
ovarian anatomy: Cortex
outer layer
consists primarily of follicles in various stages
covered by dense connective tissue TUNICA ALBUGINEA
TUNICA ALBUGINEA COVERED BY THIN LAYER OF CELLS- GERMINAL EPITHELIUM
Ovarian anatomy: Medulla
central portion
composed of connective tissue - blood nerves lymphatics
smooth muscle at hilum
what do ovaries produce?
an OVUM (a reproductive cell)
hormones
Ovarian Ligament
medial support
originate bilaterally at the cornua of the uterus
attach to lower pole of ovary
keeps ovary close to uterus
suspensory ligament of the ovary
aka: infundibulopelvic
from infundibulum to Fallopian tube/ovary to sidewall of pelvis
keeps ovary close to Fallopian tube
Mesovarioum (ovarian support)
attaches ovary to posterior aspect of broad ligament
What is the pelvic vasculature?
Ao -> common iliac arteries -> uterine artery -> arcuate arteries -> radial arteries -> straight and spiral arteries
VENOUS SYSTEM:
left ovarian vein drains into left renal vein
right ovarian vein drains directly into IVC
common iliac arteries
external and internal iliac (hypogastric) arteries
external iliac arteries continue to legs- femoral artery
internal iliac arteries feed bladder, uterus, vagina and rectum
uterine artery
anterior branch of internal iliac artery - through the base of broad ligament to cervix
tortuous
spirals up sides of uterus to cornua
travels laterally to anastomose with ovarian artery
arcuate arteries
many branches perforate serosa, carry blood to myometrium…these form the arcuate arteries
circle uterus
visualized in outer 3rd of uterus as anechoic tubular structures
radial arteries
branches of arcuate arteries
penetrate myometrium at 90 degree angle to base of endometrium
spiral arteries
supply zona basalis of endometrium
lengthen during regeneration of endometrium after menses to supply zona functionalis
supply blood to inner 2/3 of endometrium
supply proliferating endometrium each menstrual cycle
blood from spiral arteries is shed during menses
responds to hormonal changes of ovary
straight arteries
supply zona basalis of endometrium
supply blood for outer 1/3 of endometrium
NOT affected by menstrual cycle
maintains blood supply
allows regrowth of endometrium
