Anatomy and Physiology Ch 41 Flashcards
external pelvic landmarks
- mons pubis
- labia majora
- labia minora
- clitoris
- urethral opening
- vestibule of vagina
the bony pelvis consists four bones
- Two innominate (coxal) bones
- Sacrum
- Coccyx
Divided into two continuous compartments by oblique plane that passes through pelvic brim
- True Pelvis
- False Pelvis
True Pelvis is considered
the pelvic cavity, and is situated inferior to the caudal portion of the parietal peritoneum
Posterior wall is formed by the
sacrum and coccyx
Posterolateral wall is formed by the
piriformis and coccygeus muscles.
Anterolateral walls formed by the
hip bones and obturator internus muscles.
Lower margin of pelvic cavity (the pelvic floor) formed by
levator ani and coccygeus muscles.
The pelvic floor is also known as the
pelvic diaphragm.
Area below the pelvic floor is the
perineum.
Posteriorly pelvic cavity occupied by the
- rectum
- colon
- ileum
Anteriorly pelvic cavity occupied by the
- bladder
- ureters
- ovaries
- fallopian tubes
- uterus
- vagina
true pelvic musculature
- Piriformis (posterolateral wall)
- Obturator Internus (anterolateral pelvic sidewall)
- Levator Ani (Pelvic Floor/Diaphragm)
- Coccygeus (Posterior Pelvic Floor/ Diaphragm)
false pelvic musculature
- Psoas Major (pelvic sidewall)
- Iliacus (pelvic sidewall)
- In the false pelvis, psoas muscles join with the iliacus muscles to form iliopsoas muscles.
Bladder Apex
posterior to pubic bones
Bladder Base
anterior to vagina
Ureters run
anterior to internal iliac arteries and posterior to the ovaries
Coarse anterior and lateral to
upper vagina where they then enter posteroinferior bladder
Location ureters enter bladder are also where
“ureteral jets” can be seen.
vagina
Collapsed muscular tube that extends from external genitalia to the cervix.
vagina is posterior
to bladder and urethra
Normal position of the vagina is
directed upward and backward, forming a 90 degree angle with cervix.
vagina is approximately
9cm in length
vagina is anterior
to rectum
cervix
protrudes into upper portion of vaginal canal forming four archlike recesses known as fornices.
The cervix is a continuous
ring-shaped space with posterior fornix running deeper than anterior counterpart.
The endocervix communicates with the
uterine cavity by the internal os and the vagina with the external os.
The exocervix is continuous
with the vagina
uterus
Hollow, pear-shaped organ
uterus divided into three main parts:
fundus, body, cervix
uterus usually in the
anteverted or anteflexed position, but can be retroverted or retroflexed
Round ligaments hold the uterus in
anteverted position.
Premenarchal
1-3cm in length by 0.5-1cm wide
Menarchal
6-8cm in length by 3-5cm wide
Multiparity
increase in size by 1-2cm
Postmenopausal
3.5-5.5cm in length by 2-3cm wide
uterine position usually in the
anteverted or anteflexed position, but can be retroverted or retroflexed
Flexion refers to
axis of uterine body relative to cervix
Version refers to
axis of cervix relative to vagina
layers of the uterus
- perimetrium
- myometrium
- endometrium
Perimetrium
serous, outer layer of uterus
Myometrium
muscular middle layer of uterus composed of thick, smooth muscle
Endometrium
inner mucous membrane, glandular portion of uterine body
uterine ligaments
- broad
- round
- cardinal
- uterosacral
- suspensory
- ovarian
Broad
lateral aspect of uterus to pelvic sidewall
Round
fundus to anterior pelvic sidewalls, holds uterus forward
Cardinal
extend across pelvic floor laterally, supports cervix
Uterosacral
extend from uterine isthmus downward, along rectum to sacrum, also supports cervix
Suspensory
extends from lateral aspect of ovary to pelvic sidewall
Ovarian
extends medially from ovary to uterine cornua
parts of the fallopian tubes projections that overlie ovary
- interstitial
- isthmus
- ampulla
- infundibulum
Interstitial
pierces uterine wall at cornua
Isthmus
hardest part, lateral to uterus
Ampulla
widest part of tube, location of fertilization
Infundibulum
funnel-shaped tube, free edge of the funnel has fimbriae (finger-like projections that overlie ovary
ovaries
Almond shaped
ovaries attached to
broad ligament by mesovarium
ovaries supported medially by
ovarian ligaments and laterally by suspensory (infundibulopelvic) ligament
Ovarian fossa bounded by
external iliac vessels, ureter, and obturator nerve
ovarian blood Supply
ovarian artery and uterine artery
ovaries blood drained by
ovarian vein into IVC on right and into renal vein on left
ovaries vary in
pelvic location
ovaries made up of
outer layer (cortex), which surrounds the central medulla
ovaries cortex covered by
layer of dense connective tissue known as the tunica albuginea
ovaries medulla composed of
connective tissue containing blood, nerves, lymphatic vessels and smooth muscle at hilum
ovaries produce
reproductive cell- ovum
ovaries secretes two hormones
- estrogen (secreted by follicles)
- progesterone (secreted by corpus luteum)
ovarian hormones are responsible for
producing and maintaining gender characteristics (mammary glands in females, etc.), and preparing uterus for pregnancy
pelvic vasculature
-External Iliac Arteries- medial to psoas border
- External Iliac Veins- medial and posterior to arteries
- Internal Iliac Arteries- posterior to ureters and ovaries
- Internal Iliac Veins- posterior to arteries
- Uterine Arteries and Veins- between layers of broad ligaments, lateral to uterus
pelvic vasculature continued
- Arcuate arteries: arc-like arteries that encircle uterus in outer third of myometrium
- Radial arteries: branches of arcuate arteries that extend from myometrium to base of endometrium
- Straight and spiral arteries: branches of radial arteries that supply zona basalis of endometrium
- Ovarian arteries: branch laterally off aorta, run within suspensory ligaments and anastomose with uterine arteries
Female reproductive years begin around
11 to 13 years of age at onset of menses
menstrual cycle ends around age
50, when menses ceases
menstrual cycle is approximately
28 days in length
Premenarche
prepubescent
Menarche
menstruating approximately once a month
Menopause
cessation of menses
approximately 28 days
beginning with first day of menstrual bleeding
polymenorrheic
Cycle occurs at intervals of less than 21 days-
oligomenorrhic
Cycle prolonged for more than 35 day
Menorrhagia
abnormally heavy or long periods
Dysmenorrhea
painful periods
Amenorrhea
absence of menstruation
Proliferative Phase
- Days 1 to 14
- Corresponds to follicular phase of ovarian cycle
- Menstruation occurs on days 1 to 4
- Thin endometrium
- Estrogen level increases as ovarian follicles develop.
- Increasing estrogen levels cause uterine lining to regenerate and thicken.
- Ovulation occurs on day 14
Secretory Phase
- Days 15 to 28
- Corresponds to luteal phase of ovarian cycle
- Ruptured follicle becomes corpus luteum.
- Corpus luteum secretes progesterone.
- Endometrium thickens.
- If no pregnancy, estrogen and progesterone decrease.
- Menses on day 28
Ovulation
ovum released once a month by one of two ovaries (during menarchal years)
Ovulation usually occurs
about mid cycle around day 14 of a 28 day cycle
All ova begin to develop during
embryonic life, and remain within preantral follicle as an immature oocyte until menses begins.
Each female ovary contains
around 200,000 oocytes at time of birth.
Process of ovulation regulated by
hypothalamus
At puberty, hypothalamus begins releasing
gonadotropin-releasing hormones (GnRHs)
GnRHs stimulate
anterior pituitary gland to secrete varying levels of gonadotropins.
Secretion of follicle-stimulating hormone
(FSH) by
anterior pituitary gland causes
follicles to develop during the first half of the
menstrual cycle.
The follicular phase begins on cycle day
one of menstrual bleeding and continues
until ovulation around day 14.
As follicles grow, they fill with
fluid and secrete estrogen.
Typically, 5 to 8 preantral follicles begin to
develop, but
only one reaches full maturity.
Mature follicle is known as the
graafian follicle- around 2cm right before ovulation
As estrogen level in the blood rises,
pituitary gland inhibited from further
production of FSH, and then starts secreting luteinizing hormone (LH)
LH level will normally increase rapidly
24-36 hours before ovulation, this
process is known as LH surge (used to predict release of ovum)
LH level usually peaks
10–12 hours prior to ovulation
Ovulation is the explosive release of the
ovum from the ruptured dominant follicle
(graafian follicle)
Can be associated with
small amount of fluid in the posterior cul-de-sac
Midcycle dull ache on either side
of lower abdomen (pelvic area) lasting a few hours
is known as “mittelschmerz” (from German origin meaning “middle pain”)
After ovulation,
ovary enters luteal phase, which lasts about 14 days
Menstruation usually occurs
14 days after ovulation
During luteal phase,
cells in lining of ruptured ovarian follicle begin to multiply and create the corpus luteum (this process is known as luteinization, stimulated by LH surge)
Corpus luteum immediately begins
secreting progesterone
9 to 11 days after ovulation,
the corpus luteum degenerates, causing progesterone levels to decline
As those levels decline,
menstruation occurs and cycle begins again
If conception and implantation has occurred,
the human chorionic gonadotropin (hCG) produced by the zygote will cause the corpus luteum to persist
Will continue to secrete
progesterone for 3 more months until placenta takes over
Varying levels of
estrogen and progesterone throughout menstrual cycle induce changes in
endometrium, changes correlate with ovulatory cycles of ovary
Typical endometrial cycle identified and described in
three phases, beginning with menstrual
phase.
Menstrual phase lasts approximately
1 to 5 days and begins with declining progesterone levels, causing spiral arterioles to constrict.
Causes decreased
blood flow to endometrium, resulting in ischemia and shedding of zona functionalis.
First 5 days coincide with
follicular phase of ovarian cycle.
As follicles produce estrogen,
.
estrogen stimulates superficial layer of endometrium to regenerate and grow.
Phase of endometrial regeneration called
proliferative phase and will last until luteinization of graafian follicle
around ovulation.
With ovulation and luteinization of graafian follicle,
progesterone secreted by ovary causes spiral arteries and
endometrial glands to enlarge.
Prepares endometrium for
implantation, should conception occur.
Endometrial phase after ovulation referred to as
secretory phase.
Extends from approximately
day 15 to onset of menses (day 28).
Secretory phase of endometrial cycle corresponds to
luteal phase of ovarian cycle
Sonographic appearance of endometrium changes
dramatically
among the three phases of endometrial cycle.
endometrium changes should be
correlated to patient’s menstrual status.
Thickness of endometrium will
decrease with menstruation,
becoming thin echogenic line during early proliferative phase.
As regeneration of endometrium occurs,
endo will thicken to an average of 4 to 8 mm in proliferative phase, when measured as double layer from anterior to posterior. (“three-line” sign)
Three echogenic lines seen in
proliferative endometrium represent zona basalis anteriorly and posteriorly, with central line representing uterine cavity.
Right before ovulation, endometrium measures
6 to 10 mm and becomes
isoechoic with myometrium.
After ovulation, during secretory phase,
endometrium reaches thickest
dimension, averaging 7 to 14 mm.
Becomes echogenic,
blurring “three-line” appearance
Postmenopausal patients who are not on HRT should have endometrial thickness of
<5 mm.
Postmenopausal patients on HRT or taking
tamoxifen may demonstrate
normal endometrial thicknesses up to 8 mm.
Vesicouterine pouch:
anterior cul-de-sac; anterior to fundus between uterus and bladder
Rectouterine pouch (Pouch of Douglas):
posterior cul-de-sac; posterior to uterine body
and cervix, between uterus and rectum
Retropubic space:
space of Retzius; between bladder and symphysis pubis
