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

MOB TCD

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

MOB TCD

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

MOB TCD

• 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

MOB TCD

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

MOB TCD

• 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

MOB TCD

Pelvic Fascia

3. Pelvic viscera • Fascia of pelvic viscera is loose or

dense depending on dispensability of organ

Smout et al., 1969

MOB TCD

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

MOB TCD

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

MOB TCD

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

MOB TCD

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

MOB TCD

• 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

MOB TCD

• 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

MOB TCD

• 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,

MOB TCD

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

MOB TCD

• 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

MOB TCD

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

MOB TCD

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

MOB TCD

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

MOB TCD

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

MOB TCD

Blood Supply

• Uterine from internal iliac• Ovarian from aorta at L2• Vaginal arteries from internal iliac• Anterior and posterior arcuate run in

middle layer

MOB TCD

• 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

MOB TCD

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

MOB TCD

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

MOB TCD

• 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

MOB TCD

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

MOB TCD

• 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

MOB TCD

Uterine Artery

• Uterine artery lies superior to the ureter at lateral fornix of vagina

• Base of broad ligament

MOB TCD

• 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

MOB TCD

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

MOB TCD

Blood and Nerve Supply Vagina

• Uterine artery• Vaginal• Internal pudendal• Labial• Ilio Inguinal nerve supplies the

anterior wall• Labial nerves supply the

posterior wall

MOB TCD

Lymphatics of Vagina

• Internal iliac• Lower third• Medial group of proximal

superficial inguinal glands

MOB TCD

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

MOB TCD

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

MOB TCD

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

MOB TCD

• 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

MOB TCD

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

MOB TCD

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

MOB TCD

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

MOB TCD

• 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

MOB TCD

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

MOB TCD

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

MOB TCD

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 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

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.

MOB TCD

“BMJ Publishing Group Limited (“BMJ Group”) 2012. All rights reserved.”