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MOB TCD
Review of Pevic Anatomyfor Gynaecologists
Professor Emeritus Moira O’Brien
FRCPI, FFSEM, FFSEM (UK), FTCD
Trinity College
Dublin
Female Pelvis
Smout et al., 1969
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Overview MOB TCD
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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• 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
Sacroiliac Joint Accessory Ligaments MOB TCD
Abnormalities of Pelvis
• 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• CoccygeusSmout et al., 1969
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• 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 branchesSmout et al., 1969
Lateral Walls of Pelvis MOB TCD
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 lymphaticsSmout 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 stoolStoker, 2009
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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
superficial pouch
deep pouch
sphincter
urethrae
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perineal
membrane
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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• 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 coccyxLast 1984
Levator Ani MOB TCD
• 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
Levator Ani MOB TCD
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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• 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
Levator Ani MOB TCD
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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• 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
Female Bladder MOB TCD
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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• 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 glandsSmout et al 1969
Urethra MOB TCD
• Urethra is supported by the fascia of the pelvic floor including pubo-vesical 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
Urethra MOB TCD
• 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
Uterus MOB TCD
• 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
Uterus MOB TCD
• 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
Cervix MOB TCD
• 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
Cervix MOB TCD
Supports of Uterus
• 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
• 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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• 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
Blood Supply MOB TCD
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 MOB TCD
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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• 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
Contents of Broad Ligament MOB TCD
• 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
Broad Ligament MOB TCD
Broad Ligament MOB TCD
Uterine Tube
• 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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• 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
Ovary MOB TCD
• 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
Ovary MOB TCD
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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• 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 pubo-
vaginalis portion of the levator ani
Vagina MOB TCD
• 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
superficial
Vagina MOB TCD
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
• 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
• 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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• 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
Rectum MOB TCD
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
• 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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• 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
Anal Canal MOB TCD
• 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
Muscles of Anal Canal MOB TCD
• 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
Muscles of Anal Canal MOB TCD
• 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
Anal Canal MOB TCD
Blood and Nerve Supply
• 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
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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
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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
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• 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
Ischiorectal Fossa MOB TCD
Pudendal Canal
• Runs posterior to anterior• Pudendal canal contents• Pudendal nerve• Inferior rectal nerve• Dorsal nerve of clitoris• Perineal nerve• Labial nerves• Internal pudendal vessels
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Pudendal Block
• Pudendal nerve • Lies on the sacrospinous ligament• Anaesthetizes posterior wall of the
vagina• Ilioinguinal nerve supplies the anterior
wall
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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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