Download Review of Pelvic Anatomy

MOB TCD
Review of Pevic Anatomy
for Gynaecologists
Professor Emeritus Moira O’Brien
FRCPI, FFSEM, FFSEM (UK), FTCD
Trinity College
Dublin
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Female Pelvis
Smout et al., 1969
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Overview
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Bones
Joints
Fascia
Muscles
Bladder
Urethra
Uterus
• Broad
ligament
• Ovary
• Vagina
• Rectum
• Anal Canal
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Pubic Symphysis
• Secondary cartilagenous joint
• Articular surface of medial aspect of
body of pubis
• Covered with hyaline articular cartilage
• Disc of fibro-cartilage in between
• A cavity may develop in the disc but it is
not lined with synovial membrane
• There is normally very little movement
at the pubic symphysis, except during
the latter months of pregnancy
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Sacroiliac Joint
• Modified synovial plane joint
• Articular surfaces are rough
• The capsule is attached just beyond
the articular margin
• The interosseous sacroiliac ligament
is one of the strongest ligaments in the
body and is posterior to the joint
• This articulation is almost immobile,
except during pregnancy
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Sacroiliac Joint Accessory Ligaments
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Sacrotuberous ligaments
Sacrospinous ligaments
Iliolumbar ligaments
Posterior superior iliac spine is middle of
the joint posteriorly at the level S2
• S2 is end of dura, arachnoid mater and
subarachnoid space
• During gait, the amount of accessory
movement at the sacroiliac joint helps to
protect the lumbar intervertebral discs
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Abnormalities of Pelvis
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Spina bifida occulta
Unilateral lumbarisation
Unilateral sacralisation
Stress fractures of the
sacrum, pubic arch and neck
of femur may be first signs of
osteoporosis
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Walls of Pelvis
• Sacrum and coccyx posterior
• Os coxae below pelvic brim
• Piriformis covers middle three
pieces of sacrum
• Passes out of the pelvis through
the greater sciatic foramen
• Muscles
• Obturator internus muscle
• Origin of levator ani
• Coccygeus
Smout et al., 1969
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Lateral Walls of Pelvis
• Obturator nerve
• Obturator artery and vein
• Parietal peritoneum supplied by
the obturator nerve
• Pain may be referred to hip or
knee joints
• Common iliac divides into
external and internal iliac
• Internal divides into anterior and
posterior division branches
Smout et al., 1969
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Pelvic Fascia
Pelvic fascia can be divided into three:
1. Pelvic wall
• Pelvic fascia is a strong membrane over
the piriformis and obturator internus
• Fuses with the periosteum at their
margins
2. Pelvic floor
• Fascia is covered with loose areolar tissue
• Loose areolar fat tissue lies in the extraperitoneal
space between peritoneum and the viscera forming a
dead space
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Pelvic Fascia
3. Pelvic viscera
• Fascia of pelvic viscera is loose or
dense depending on dispensability of
organ
Smout et al., 1969
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Pelvic Ligaments
• Condensation around vessels form
ligaments in the pelvis
• Cardinal ligament condensation of
fascia around uterine artery
• Lateral ligament of the rectum is a
condensation of fascia around the
middle rectal vessels and branches of
the hypogastric plexus
• Waldyer’s fascia suspends the lower part of the ampulla
of the rectum to the hollow of sacrum
• Contains the superior rectal vessels and lymphatics
Smout et al., 1969
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Pelvic Floor
• Urogenital diaphragm
• Perineal membrane and the superficial
transverse perineii
• The pelvic floor is a dome-shaped
striated muscular sheet
• The levator ani is made up mainly of
the pubococcygeus, the puborectalis
and the iliococcygeus
• It encloses the bladder, uterus and rectum
• Together with the anal sphincters, has an important role
in regulating storage and evacuation of urine and stool
Stoker, 2009
Deep Perineal Pouch:
Urogenital Diaphragm
• Superior is the areolar tissue on the
under surface of the levator ani
• The sphincter urethrae around urethra
and transverse perineii in the deep
pouch
• Perineal membrane fills in pubic arch
below the muscles
• Muscles are supplied by perineal
branch of pudendal nerve
• In lateral portion of the deep pouch, run
dorsal nerve of clitoris and internal
pudendal artery and vena commitans
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perineal
membrane
deep pouch
superficial
pouch
sphincter
urethrae
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Levator Ani
• Arises, anteriorly, from the posterior
surface of the body of pubis lateral to
the symphysis
• Posterior from the inner surface of the
spine of the ischium
• Between these two points, from a
tendinous arch called the white line
(arcus tendineus) adherent to the
obturator fascia
Last,1984
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Levator Ani
• Unites with the opposite side to form
most of the floor of the pelvic cavity
• The fibres pass downward and
backward to the middle line of the floor
of the pelvis
• Inserted from before backwards, into
perineal body
• Side of the rectum and anal canal
• Anococcygeal raphe
• The side of the last two segments of
the coccyx
Last 1984
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Levator Ani
• The anterior fibres, pubovaginalis,
pass behind the vagina, unites with
the opposite side
• Inserted into the perineal body, the
central point of the perineum
• Joining the fibres of the sphincter ani
externus and transversus perineii
Last 1984
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Levator Ani
• The puborectalis forms a U-shaped
sling, holding the anorectal anteriorly,
blending with the deep fibres of the
external anal sphincter
• Anococcygeal raphe lies between the
coccyx and the margin of the anus
• Nerve supply, inferior rectal nerve
and perineal branch fourth sacral
Last 1984
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Levator Ani
• In women, the levator muscles or their
nerve supply, can be damaged in
pregnancy or childbirth
• There is some evidence that these
muscles may also be damaged during
a hysterectomy
• Pelvic surgery using the "perineal
approach" (between the anus and
coccyx) is an established cause of
damage to the pelvic floor. This
surgery includes coccygectomy
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Empty Female Bladder
• Bladder has a apex, triangular superior
surface, base and two inferolateral
surfaces, neck inferiorly
• Posterior or base is fixed, the two
ureters enter obliquely at the junction
of the superior surfaces and base
• The internal urethral orifice or neck is
at the junction of the base and two
inferolateral surfaces
• The interior of the bladder is lined with
transitional epithelium which is thrown into folds
in the empty bladder, except for the smooth
triangular area of base called trigone
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Female Bladder
• Pubo vesical ligaments connect the
neck to the pubic bone
• Base is attached to the supravaginal
portion of the cervix and anterior
fornix of vagina
• Peritoneum only covers superior
surface
• Blood supply, superior and inferior
vesical arteries
• Venous plexus into internal iliac vein
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Control of Micturition
• Smooth or detrusor muscle at the
neck is the internal sphincter,
supplied by the sympathetic
• Parasympathetic contracts
detrusor muscle and relaxes
internal sphincter
• Sphincter urethra or external
sphincter is striated muscle
• Supplied by perineal branch of
pudendal nerve S2,3,4,
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Structure of Female Urethra
• Urethra 3-5 cm long
• Enters deep pouch where it is
surrounded by
• Sphincter urethra, also called external
sphincter of bladder
• Urethra pierces perineal membrane
• No fascia between lower two thirds of
urethra and vagina
• Opens into vestibule, between clitoris
and vagina
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Urethra
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Muscular layer continuous with bladder
Spongy erectile tissue
Plexus of veins
Mucous membrane transitional
Distal non keratinising stratified squamous
Para urethral glands and ducts open into
urethra, homologues of prostatic glands
Smout et al 1969
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Urethra
• Urethra is supported by the fascia of
the pelvic floor including pubovesical and pubocervical ligaments
• If this support is insufficient, the
urethra can move downwards
• In times of increased abdominal
pressure resulting in stress urinary
incontinence (SUI)
• The physical changes that can occur during pregnancy,
delivery and menopause can predispose to SUI
Nuggaard and Heit in Bayliss 2010
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Uterus
• Normal uterus is anteverted
• i.e. anterior to vertical plane going
through the vagina
• Posterior fornix deeper
• Anteflexed
• Bent anteriorly junction of body and
cervix
• Pear-shaped muscular organ
• 8 cm long; 5 cm width; 3 cm thick
• Non-pregnant state
• Pelvic organ
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Uterus
• Fundus
• Body
• Cervix opens into vault or fornices
of vagina
• Fundus is the portion above
entrance of uterine tubes
• Covered with peritoneum
• Body
• Triangular cavity
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Cervix
• Isthmus is a circular borderline area
between the body and cervix
• Isthmus is the supra vaginal portion
of cervix, the lower uterine segment
• Intravaginal is surrounded by gutter
by fornices of vagina,
• Posterior is deeper covered with
peritoneum
• Internal os is the opening from the
cavity of body
• Spindle shaped cavity cervix
• External os is the opening into vagina
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Cervix
• Cervical canal is lined by columnar
epithelium
• External os
• Junction of columnar of the cervical
canal
• Stratified epithelium of the
intravaginal portion
• Site of cancer of cervix
• Cervical smear
• At birth cervix is larger than the body
• Fully developed
• Cervix is one third of body
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Supports of Uterus
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Upper
Round ligament
Broad ligament anteverted
Transverse ligament
Pubocervical
Uterosacral
Lower
Levator ani, coccygeus
Perineal body
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Round Ligament
• Round ligament and ligament of
ovary
• Develop from the gubernaculum
• Side of uterus, junction fundus and
body
• Inguinal canal to labium majus
• Ante version
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Pubocervical Ligament
• Attached
• Anteriorly to posterior aspect of body
of body of pubis
• Passes to neck of bladder
• Anterior fornix of vagina
• Pubocervical ligaments help to
• Maintain normal angle of 45°
between the vagina and horizontal
• Decrease may cause a cystocoele
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Transverse Ligament
• Transverse or cardinal or
Mackenrodt’s ligament
• Thickening of visceral layer of pelvic
fascia around uterine artery
• Lateral to medial in base of broad
ligament
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Uterosacral Ligament
• Uterosacral contains fibrous tissue
• Non-striated muscle
• Attached from the cervix to the
middle of sacrum
• Contains lymphatics draining cervix
to sacral glands
• Uterosacral help to keep uterus
anteverted
• If uterus is anteverted it cannot
prolapse
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Blood Supply
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Uterine from internal iliac
Ovarian from aorta at L2
Vaginal arteries from internal iliac
Anterior and posterior arcuate run in
middle layer
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Blood Supply
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Serous layer
Myometrium
No submucous layer
Endometrium
Compact at surface of uterine cavity
and spongy layer are supplied by
spiral arteries
• Basal layer is not shed during
menstruation; supplied by radial branches
• Veins below artery
• Plexus in lower edge broad ligament into
internal iliac
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Embolization of Fibroids
• Fibroids vary in size and position in
uterine wall
• May enlarge and compress ureters
or other structures in pelvis
• A small catheter is inserted in the
groin, into the femoral artery
• Small particles are introduced
through the catheter into the uterine
artery
• They block the blood supply to the fibroids
• The fibroids thus starved of blood shrivel and die
over the next few months
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Lymphatics of Uterus and Vagina
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Nerve Supply of Uterus
• Pain from cervix via
parasympathetic S2,3
• Pain from body via
sympathetic to T11 and
T12
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Broad Ligament
• Fold of peritoneum from side of uterus
to side wall of pelvis
• Framework of pelvic fascia
• Parametric fat
• Anterior surface looks inferiorly
• Free upper border
• Base lies on pelvic floor
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Contents of Broad Ligament
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Uterine tubes
Ovarian vessels
Uterine vessels
Epoophoron
Paroophoron
Round ligament of uterus and
ligament of ovary
• Transverse ligament
• Ovary attached to posterior layer
• Ureter in base below uterine artery
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Broad Ligament
• Uterine tube lies in medial four fifths
of free border of broad ligament
• Lateral one fifth
• Contains ovarian vessels
• Infundibulo-pelvic or suspensory
ligament of ovary
• Epoophoron
• Parallel tubules remains of
mesonephric tubules
• Gartner's duct remains of
mesonephric duct, may form cysts
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Broad Ligament
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Uterine Tube
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Intramural
Isthmus
Ampulla
Infundibulum surrounded by fimbria
Lined ciliated columnar epithelium
Beats towards uterus
Peritoneum loosely attached to ampulla
Tightly to isthmus, if ectopic implanted
here, ruptures earlier
• Fimbria surrounding opening into peritoneal cavity
• Ovarian fimbria is longest
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Ovary
• Attached to posterior layer of broad
ligament meso ovarian
• Covered with germinal epithelium
• Related to side wall of pelvis which is
covered with peritoneum
• Obturator internus muscle
• Obturator nerve supplies the parietal
peritoneum
• Posterior to ovary is the ureter
• Ligament of ovary medially
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Ovary
• Obturator nerve supplies the parietal
peritoneum
• Irritation of the peritoneum of the side
wall by bleeding at ovulation or by
lesions involving the ovary
• May result in referred pain to medial
side of the thigh or the knee
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Ovary
• Blood supply
• One ovarian artery from lateral
aspects of aorta L2
• Right vein drains into inferior vena
cava
• Left drains into left renal vein
• Lymphatics into para aortic
glands L2
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Vagina
• Fornices, gutters which surround the
cervix
• Normal anteverted antiflexed
• Anterior fornix is shallow anterior wall is
shorter than posterior
• Posterior deeper, covered with
peritoneum of the pouch of Douglas
• Most dependent part of peritoneal cavity
• Walls in contact except superior
• Opens into vestibule of vagina
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Uterine Artery
• Uterine artery lies superior to the
ureter at lateral fornix of vagina
• Base of broad ligament
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Vagina
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Erectile tissue
Muscular wall
Pelvic fascia
Nonkeratinised stratified squamous
epithelium
• Urethra lower third anterior wall
• No fascia between lower two thirds of
urethra and vagina
• Upper portion of the vagina is clasped by the pubovaginalis portion of the levator ani
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Vagina
superficial
• Deep pouch
• Sphincter urethrae, deep transverse
perineii, pierces perineal membrane,
opens into vestibule of vagina
• Hymen fold of mucous membrane at
external opening
• Lateral are the bulbs of vestibule
• Covered by bulbospongiosus muscle
• Greater vestibular (Bartholin's) glands lie
behind the bulbs of vestibule
• Ducts open into orifice of the vagina
• Posterior to vagina is the perineal body
deep
pouch
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Perineum
perineal body central
point of perineum
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Peritoneum on Uterus and Vagina
• Reflected from the superior surface of
the bladder
• Junction of the supravaginal portion of
the cervix and the body of the uterus
forming the utero vesical pouch
• Peritoneum then covers body, fundus
and posterior surface body and then
the supravaginal cervix and posterior
fornix of vagina
• Peritoneum then reflected on to junction of upper
two thirds and lower third of rectum forming
• Pouch of Douglas is most dependent part of
female peritoneal cavity
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Blood and Nerve Supply Vagina
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Uterine artery
Vaginal
Internal pudendal
Labial
Ilio Inguinal nerve supplies the
anterior wall
• Labial nerves supply the
posterior wall
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Lymphatics of Vagina
• Internal iliac
• Lower third
• Medial group of proximal
superficial inguinal glands
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Pelvic Plexus
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Lumbar splanchnics L1-L2
Presacral nerve
Anterior to body of L5
Divide into pelvic plexuses
Postganglionic of sympathetic
that relayed in lumbar and
sacral ganglia causes
contraction of sphincters of
bladder and anal canal
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Pelvic Parasympathetic
• Preganglionic have cell bodies in
lateral column of segments S2,3,4
• Ganglia found close to or in wall
of organ
• Supplies intestine from splenic
flexure to upper two thirds of anal
canal, bladder
• Motor to walls and inhibitory to
sphincters
• Parasympathetic causes erection
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Rectum
• Rectum is a continuation of pelvic
colon
• Starts at the third piece of the
sacrum
• Ends 5 cm from the tip of coccyx
• Lower end is dilated at the ampulla,
at the anorectal junction
• There are no taeniae and no
appendices epiplociae on the
rectum
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Rectum
• It has an antero-posterior curve,
above it is angled anteriorly by the
puborectalis
• Below convex forwards
• Three lateral curves
• Two concave to left, one to right,
where the valves of Houston, which
consist of circular muscle and
mucous membrane
• Peritoneum covers upper third on front and sides
• Middle third on front, none on lower third
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Blood Supply of Rectum
• Superior rectal, continuation of inferior
mesenteric artery
• Runs in Waldyer’s fascia from hollow
of sacrum to the lower part of the
ampulla of the rectum
• Supplies mucous membrane as far
mucocutaneous junction of anal canal
• Venous drainage into portal system
• Middle rectal the muscle layer
• Small twigs from median sacral
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Anal Canal
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Starts at anorectal junction
Below ampulla of rectum
Passes backwards
Approx 4 cm
Ends at anus
Anterior: perineal body
Posterior: anococcygeal body
Lateral: ischiorectal fossae
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Muscles of Anal Canal
• The anal sphincter is a multilayered
cylindrical structure
• The inner smooth muscle of the
internal sphincter
• Surrounds upper two thirds
• Lower two thirds the outer striated
muscle layer of the external sphincter
• Anorectal ring formed by puborectalis
and the deep part of the external
sphincter
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Peri Anal Fascia
• Perianal fascia continuation of
longitudinal coat of rectum
• Medial to deep and superficial
external sphincters
• Attached at Hilton’s line
• Passes to lateral wall
• Above subcutaneous sphincter
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Anal Canal
• Lateral sheet passes between soft
ischiorectal fat and subcutaneous fat
to lateral wall
• Splits to form pudendal canal and is
• Continuous superiorly with the lunate
fascia, which passes above soft
ischiorectal fat
• It is medial to deep and superficial
sphincter
• Above subcutaneous sphincter
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Muscles of Anal Canal
• Puborectalis portion levator ani holds
the anorectal junction anteriorly
• Deep and subcutaneous parts of
external are true sphincters
• No bony attachments
• Superficial attached to coccyx and the
perineal body
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Muscles of Anal Canal
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Anorectal ring
Internal sphincter
Puborectalis
Puborectal fascia
External sphincter
Deep, true sphincter, no bony
attachments
Inferior rectal nerve S3,4
Superficial S4
Subcutaneous, true sphincter
Inferior rectal nerve S3,4
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Anal Canal
• Upper two thirds lined by
columnar epithelium
• Lower third by skin
• Junction of two is Hilton’s white line skin
• Anal columns contain radicles of
superior rectal artery and veins 4,7,11
• At the lower end joining the columns are
mucosal folds called anal valves
• Anal sinuses lie behind
• Skin supplied by inferior rectal vessels
and nerves
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Blood and Nerve Supply
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Upper two thirds
Columnar epithelium
Superior rectal artery
Autonomic nerves
Derived from cloacae
Lower third
Skin
Inferior rectal S3,4,
Somatic nerves
Derived from proctodeum
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Venous Drainage
• Mucosa upper two thirds
• Superior rectal vein
• Portal system
Lower third
• Inferior rectal vein
• Vein into systemic system
• Portal systemic anastomosis’ 4,7,11
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Lymphatic Drainage
Upper third
• Pre aortic inferior mesenteric
• Waldeyer’s fascia passes from sacrum to
the ampulla of rectum
• Encloses superior rectal vessels and
lymphatics
• Internal iliac
Lower Third
• Inferior rectal cross ischio-rectal fossa
• Medial superficial inguinal glands
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Anal Sphincters
• The internal and external anal
sphincters are primarily
responsible for maintaining faecal
continence at rest and when
continence is threatened,
respectively.
• Defecation is a somato-visceral
reflex regulated by dual nerve
supply (i.e. somatic and
autonomic) to the anorectum.
Bharucha 2006
MOB TCD
Anal Sphincters
• The net effects of sympathetic and
cholinergic stimulation are to
increase and reduce anal resting
pressure, respectively.
• Faecal incontinence and
functional defecatory disorders
may result from structural
changes and/or functional
disturbances in the mechanisms
of faecal continence and
defecation.
Bharucha 2006
MOB TCD
Ischiorectal Fossa
Ischiorectal fossa contents
• Soft ischiorectal fat
• Lunate fascia above the fat
• Inferior rectal vessels pass above
the fat to reach medial wall
• Perineal branch of S4
ischiorectal fossa
MOB TCD
Ischiorectal Fossa
• Ischiorectal fossa contents
lunate fascia above the soft
ischiorectal fat
• Inferior rectal vessels and nerve
pass above lunate fascia and the
fat to reach medial wall
• Subcutaneous fat lies below
perianal fascia
• Perineal branch of S4
• Lymphatics cross fossa
MOB TCD
Pudendal Canal
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Runs posterior to anterior
Pudendal canal contents
Pudendal nerve
Inferior rectal nerve
Dorsal nerve of clitoris
Perineal nerve
Labial nerves
Internal pudendal vessels
MOB TCD
Pudendal Block
• Pudendal nerve
• Lies on the sacrospinous ligament
• Anaesthetizes posterior wall of the
vagina
• Ilioinguinal nerve supplies the anterior
wall
MOB TCD
Age, pregnancy, family history, and hormonal status all
contribute to the development of pelvic organ prolapse. The
vagina is suspended by attachments to the perineum, pelvic
side wall and sacrum via attachments that include collagen,
elastin, and smooth muscle. Surgery can be performed to
repair pelvic floor muscles. The pelvic floor muscles can be
strengthened with Kegel exercises.
Disorders of the posterior pelvic floor include rectal
prolapse, rectocele, perineal hernia, and a number of
functional disorders including anismus. Constipation due to
any of these disorders is called "functional constipation"
and is identifiable by clinical diagnostic criteria.
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