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Ovaries – develop high on the posterior abdominal wall and descend before birth, bringing their vessels, lymphatics and nerves. They lie on the lateral pelvic wall just inferior to the pelvic inlet.
- Lateral surface – related to obturator vessels and nerve of the lateral pelvic wall
- Medial surface – largely covered by uterine tube
- Tubal (superior) end – ovarian fimbria and suspensory ligament of the ovary (containing ovarian vessels and nerves) attached to it
- Uterine (inferior) end – faces pelvic floor and attached to side of the uterine body by the ovarian ligament
- Mesovarian border – attached to back of the broad ligament by the mesovarium
- Free border – faces the ureter
Uterine tubes – about 10cm long, extending from the upper lateral margin of the uterus to the ovary. Divided into:
- Infundibulum – trumpet-shaped with numerous fimbriae (finger-like projections). Contains the peritoneal opening (abdominal ostium) within its depths
- Ampulla – tortuous, thin-walled dilated area; fertilisation usually occurs here
- Isthmus – narrowest part
- Intramural – portion within the wall; contains uterine ostium
Uterus – position between the urinary bladder anteriorly and rectum posteriorly; comprised of:
- Fundus – portion above the uterine tube attachments
- Body –lateral margins receive attachments of the ligament of the ovary, and uterine round and broad ligaments
- Isthmus – narrowest portion; about 1cm in length
- Cervix – most posterior portion, about 2.5cm. Meets the vagina at right angles and bulges into the anterior vaginal wall. The cervical canal communicates with the body cavity via the internal os, and with the vagina via the external os (in nulliparous women this is rounded, but has anterior and posterior folds in parous women)
Uterine ligaments – the pelvic and urogenital diaphragms and the perineal body are the main supports of the uterus. The uterus is also attached to surrounding structures via several ligaments, some of which provide some support:
- Broad ligament – mesenteric folds of peritoneum extending from the lateral margins of the uterus to the lateral walls of the pelvic cavity. It covers the surfaces of the uterine body and reflects onto the bladder and rectum, forming vesicouterine and rectouterine pouches respectively. Consists of 3 parts:
- Mesometrium – lower part, from the lateral wall of the uterus to lateral wall of pelvic cavity. Contained between peritoneal layers of the mesometrium are the ovarian ligament, round ligament of the uterus, part of the ureter and vessels and nerves
- Mesosalpinx – top part, extends around uterine tube
- Mesovarium – fold of peritoneum extending posteriorly to attach to the ovary's mesovarian border
- Round ligaments of the uterus – 10-12cm long extending from the lateral aspect of the uterus, passing anteriorly between layers of the broad ligament to leave the abdomen through the inguinal canal and insert onto labia majora
- Transverse cervical ligaments (cardinal lig.); extend from side of cervix to upper fascia of pelvic diaphragm
- Uterosacral ligaments – contained in the uterosacral folds which connect uterus with sacrum
Uterine positions – may change depending on fullness of bladder and pregnancy, but normal position is:
- Anteversion – long axis of the cervix 90· to the long axis of the vagina
- Anteflexion – long axis of the cavity of the body of the uterus at 150· to the long axis of the cervical canal
Vagina – a fibromuscular tube extending from the cervix to the vestibule. Its anterior wall is 7.5cm, with relations to the urethra and base of bladder. The posterior wall is 9cm and related to peritoneum, perineal body and rectoanal canal.
Vulva (external genitalia) – includes:
- Mons pubis – elevation in front of the pubic symphysis
- Labia majora – two prominent folds forming the boundaries of the pudendal cleft. External surfaces are hairy and pigmented, with internal surface pink and hairless.
- Labia minora – two small folds lacking fat and hair; medial to the labia majora. Contribute anteriorly to the frenulum and prepuce of the clitoris
- Vestibule – space between labia minora, containing vaginal and urethral orifices
- Clitoris – erectile tissue; comprised of two crura extending along the ischiopubic rami to the pubic symphysis. The crura are covered by ischiocavernosus muscles, and extend off the pubic symphysis as to small corpora cavernosa. These together form the body of the clitoris. The glans clitoris is a small spongy tubercle that surmounts the body
- Bulbs of the vestibule – (=bulbs of penis) lie on either side of the vaginal orifice and joined anteriorly. They are covered by the bulbospongiosus muscles and cover the greater vestibular gland posteriorly
- Greater vestibular glands – (=bulbourethral glands) secrete mucus for lubrication during sex
- Hymen vaginae – thin fold of mucosa lying just within the vaginal orifices of virgins
Blood supply – direct and indirect ovarian branches of the abdominal aorta. The abdominal aorta divides into its terminal branches (common ileac arteries) which subsequently divide at the pelvic inlet into external and internal iliac arteries; it is branches of these that supply most of the organs of the reproductive system:
- Ovaries – ovarian branches of the abdominal aorta, uterine artery
- Uterus – uterine artery (branch of int iliac). The uterine artery anastamoses with ovarian and vaginal arteries
- Vagina – uterine, vaginal, middle rectal and internal pudendal arteries (all branches of internal ileac)
- Vulva – external pudendal artery (branch of the femoral), and perineal, labial, artery of the bulb of the vestibule, dorsal and deep arteries of the clitoris, branches of internal pudendal artery
Venous drainage – ovaries drained via the pampiniform plexus to the ovarian vein, draining into the IVC (right side) or the left renal vein (left side). The uterine veins are arranged like arteries, with the uterine venous plexus draining into the internal ileac vein. The vagina is drained via a vaginal plexus of veins to the internal ileac vein. The vulva is drained via external and internal pudendal veins.
Lymphatic drainage –
- Ovaries, fundus and body – lumbar or paraaortic nodes
- Region around attachment of the round ligament – inguinal nodes
- Vagina – external and internal iliac, sacral nodes
- Vulva – inguinal lymph nodes
Nerve supply –
- Ovaries – autonomic supply via ovarian plexus (extension of aortic plexus); receives supply from vagus nerve and T10-11 sympathetic ganglia
- Uterus and upper vagina – autonomic, via uterovaginal plexus (extension of inferior hypogastric plexus); supply from sympathetic sacral splanchnic nerves and parasympathetic pelvic splanchnic nerves
- Lower vagina and vulva – autonomic supply via pudendal nerve which receives input from the inferior hypogastric plexus. Somatic supply via ilioinguinal nerve (L1), genital branch of the genitofemoral nerve (L1-2), perineal branch of the femoral cutaneous nerve (S1-3) and perineal nerve (branch of pudendal nerve, S2-4)
Testes – paired ovoid organs; left usually lower than right. Each has a superior and inferior end, medial and lateral surface, and anterior and posterior margin. They are covered in the fibrous tunica albuginea, which sends septa into the organ, dividing in into wedge-shaped lobules. These lobules and septa converge near the posterior margin to form the mediastinum testis (fibrous tissue continuous with tunica albuginea). Each lobule contains 1-4 seminiferous tubules which converge to 20-30 straight tubules as they approach the mediastinum. Within the mediastinum testes the straight tubules form a convoluted network, the rete testis, from which 15-20 efferent ductules project into the head of the epididymis.
Epididymis – consists of a head, body and tail, with appendices of the epididymis present on the head. The ductus deferens arises from the tail and ascends within the spermatic cord.
Between the inside wall of the scrotum and the testis is a small fluid-filled tunica vaginalis (remnant of processus vaginalis). It has visceral (covering tunica albuginea) and parietal (lines inside of scrotum) layers.
Scrotum – a fibromuscular sac containing the testis, epididymis and lower parts of the spermatic cord. It is divided into halves by the scrotal raphe. The thin scrotal skin overlies the dartos muscle that acts with the cremaster muscle to elevate the testis in cold temperatures
Spermatic cord – as the testis descend, it carries with it the vas deferens, vessels (testicular, cremasteric arteries, artery of the ductus deferens, testicular veins and lymph vessels) and nerves (genital branch of genitofemoral nerve and its cremasteric nerve branch). Surrounding these structures are layers derived from the abdominal wall:
- External spermatic fascia (from external oblique)
- Cremasteric fascia/muscle (from internal oblique)
- Internal spermatic fascia (from transversus abdominis)
Inguinal canal – 3-5cm long oblique passage through the abdominal wall, extending along the inguinal ligament from the deep to the superficial inguinal rings. The vas deferens, testicular and other small arteries, pampiniform plexus, testicular lymph vessels and nerves pass through the canal. From the inguinal canal these structures acquire layers of fascia (from abdominal wall) and from here form the spermatic cord.
- Deep inguinal ring – deep to the midinguinal point (halfway between ASIS and the midline)
- Superficial inguinal ring – 1cm superior and lateral to pubic tubercle
- Floor – inguinal ligament and lacunar ligament medially
- Roof – arching fibres of the internal oblique medially, transversus abdominis laterally
- Anterior wall – internal oblique and external oblique aponeurosis
Ductus deferens – continuation of the tail of the epididymis. Initially very tortuous, but becomes straighter as they ascend. It traverses the inguinal canal, passes the lateral pelvic wall then crosses the ureter to pass between the bladder's posterior surface and the upper pole of the seminal vesicle. At the posterior surface of the bladder it dilates (ampulla). It enters the prostate and joins the duct of the seminal vesicle to form the ejaculatory ducts; these open into the prostatic urethra on the colliculus seminalis of the urethra crest.
Seminal vesicles – coiled tubular glands lying lateral to the ampulla of the ductus deferens, posterior to the base of the bladder and anterior to the rectum.
Prostate – gland surrounding the neck of the urinary bladder and upper urethra (4x3x2cm). It has a base (adjacent to the bladder neck), an apex, posterior, anterior and inferolateral surfaces, and can be divided into two lateral lobes, a median lobe, posterior lobe and anterior segment. It may increase in size after middle age and cause obstruction of the urethra
Bulbourethral glands – about 1cm in diameter, enclosed by fibres of the sphincter urethrae; lie lateral to the membranous urethra above the perineal membrane and penile bulb. The excretory duct of each passes obliquely forwards, piercing the perineal membrane.
Penis – consists of a root attached to the perineum, and a free body Root – three masses of erectile tissue –
- Crura (2) – attached to the ischiopubic ramus and covered by the ischiocavernosus muscle
- Bulb – lies between the crura; firmly attached to the inferior aspect of the urogenital diaphragm fascia. It is overlain by the bulbospongiosus muscle and has the spongy urethra passing through it
Body – has a dorsum (posterosuperior in erection) and opposite urethral surface. Largely supported by two ligaments: fundiform and suspensory. Consists of:
- Corpus cavernosa (2) – continuous with the root's crura, enclosed in a tunica albuginea that meets in the midline as the septum of the penis. The interior contains numerous trabeculae arising from the fibrous sheathes of the corpora cavernosa; between these are spaces that fill with blood. Blood enters via central and helical arteries, and leaves via peripheral veins
- Corpus spongiosum – continuous with the bulb; expanded distally as the glans of the penis that has a ridge (corona glandis) overhanging a grooved neck of the penis. The glans is covered by a prepuce (foreskin) and a frenulum (fold of skin passing from the prepuce to the glans on the urethral surface).
Blood supply – via direct testicular branches and indirect branches of the abdominal aorta.
- Testicular arteries – two vessels arising anteriorly from the aorta slightly inferior to the renal artery. They pass anterior to psoas major and behind the parietal peritoneum; enter the spermatic cord at the deep inguinal ring and course within it to the scrotum supplying testes, cremaster m, iliac nodes and ureters
- Testicular veins – drain the testis and epididymis, unite to form the pampiniform plexus and ascend along the testicular artery. Right testicular vein drains directly into the IVC just below the right renal vein; the left into IVC via the left renal vein
- External iliac arteries –
- Inferior epigastric artery – mainly supplies anterolateral abdominal wall muscles and underlying parietal peritoneum. In males gives rise to the cremasteric artery at the deep inguinal ring; this courses within the spermatic cord to supply the cremasteric muscle and scrotum
- Femoral artery – external iliac artery passes under the inguinal ligament to become this vessel. This gives rise to the external pudendal artery that supplies the scrotum
- External iliac veins –
- Inferior epigastric vein – courses with the artery and drains the lower anterolateral abdominal wall, underlying peritoneum, spermatic cord and scrotum
- Femoral vein – receives the external pudendal vein (draining the scrotum) and superficial dorsal vein of the penis (drains the penis)
- Internal iliac arteries – numerous branches
- Superior vesical – supply ureters and bladder, gives rise to arteries that supply the ductus deferens
- Inferior vesical – supplies seminal vesicles, prostate, ejaculatory ducts, ureters and bladder
- Middle rectal – supplies seminal vesicles, prostate and rectum
- Internal pudendal – several branches that supply the pelvic diaphragm, ischiorectal fossa, anal canal, urogenital diaphragm, urethra, scrotum, root of the penis, penile crura, glans and corpora cavernosa
- Internal iliac vein – drain the penis (deep dorsal vein), prostate, seminal vesicles (prostatic plexus), and scrotum (internal pudendal vein). Also drains the pelvic wall, floor and viscera, ureter and bladder
Lymphatic drainage – series of lymph nodes largely associated with the major vessels of the abdomen and pelvis
- Lumbar – vessels from the testes, kidneys, abdominal ureter, posterior abdominal wall
- Common iliac – receive drainage from the rectum, external and internal iliac and sacral nodes
- External iliac – prostate, seminal vesicles, scrotum and penis (via superficial and deep inguinal nodes
- Internal iliac and sacral – directly drain prostate, seminal vesicles, rectum and anal canal
Nerve supply – somatic (derived from ventral rami of lumbar and sacral nerves) and autonomic (vagal and pelvic splanchnic nerves of the parasympathetic nervous system and lesser and sacral splanchnic nerves of the sympathetic) nerves Somatic supply –
- Lumbar ventral rami and plexus
- Ilioinguinal nerve – arises from L1, transmits sensory information from the scrotum and penile root
- Genitofemoral – from LI and L2, emerging through psoas major; info from scrotum via its genital branch
- Sacral ventral rami and plexus
- Posterior femoral cutaneous nerve – from S1-3; transmits sensory info from scrotum via perineal branch
- Pudendal nerve – arise from S2-4; receives and transmits info from the corpora cavernosa, spongiosum and glans penis (dorsal nerve of the penis); scrotum and spongy urethra (perineal nerve) and anal canal (rectal nerve)
Sympathetic supply –
- Lower thoracic ganglion and lesser splanchnic nerve – T9-10 sympathetic ganglia gives rise to the lesser splanchnic nerve. These supply the testes via the testicular plexus
- Sacral sympathetic ganglia and sacral splanchnic nerves – supply the prostate and seminal vesicles via inferior hypogastric and prostatic plexuses and the penile erectile tissue via inferior hypogastric plexus
Parasympathetic supply –
- Vagus nerve and renal plexus – innervate the testes
- Pelvic splanchnic nerves and hypogastric plexuses – sensory fibres innervate testes, prostate, seminal vesicles and penile erectile tissue
Erection is produced by vasodilation of the helicine arteries (parasympathetic action – "point") leading to increased blood flow into the cavernous spaces. This causes compression of the veins near the exterior of the cavernous spaces, thus deceasing outflow and increasing pressure inside the erectile tissue. Ejaculation is under sympathetic control ("shoot") and is produced by contraction of the smooth muscle of the epididymis, ductus deferens, seminal vesicle and prostrate. Some of the pelvic and urogenital diaphragm muscles undergo contraction to expel the seme
Bones – the pelvis is comprised of paired hip bones that meet at the midline pubic symphysis and the sacrum posteriorly. In its anatomical position, it is orientated so that the ASIS and pubic tubercles are in the same vertical plane. Thus, the sacrum forms the roof of the pelvic cavity (not the posterior wall) and the pubic bodies the floor.
The HIP BONES are comprised of three separate bones, joined by triradiated cartilage in the acetabulum.
- The (superior, largest) ilium has an iliac fossa and iliac crest, with a distinct thickening called the tubercle, which ends as the anterior and posterior superior iliac spines (ASIS and PSIS). Its gluteal surface faces posterolaterally, below the iliac crest. The posterior auricular (ear-shaped) surface contributes to the sacro-iliac joint, while the roughened iliac tuberosity is the attachment of ligaments
- The (posteroinferior) ischium is the sitting bone. It has a large body and a ramus that projects anteriorly to join with the inferior ramus of the pubis. The prominent ischial tuberosity sits posteroinferiorly.
- The (anteroinferior) pubis has a body with a rounded pubic crest superiorly. The two pubic bones join at the pubic symphysis, just lateral to this on each side is the prominent pubic tubercle. It has two rami – superior and ischeo-pubic (inferior, joins with the ramus of the ischium)
The pubis, ischium and associated rami contribute to the formation of the large obturator foramen. This is filled by the obturator membrane, except for the superior obturator canal that the obturator nerves and vessels pass through
The SACRUM is part of the vertebral column, and contains pelvic sacral foramina to transmit the ventral rami. There is a distinct sacral promontory superiorly and flared ala laterally that are part of the sacroiliac joints.
|* Subpubic angle (under symphysis) acute – 60˚
||* Larger subpubic angle – 85-90˚ allows fetal head extension
There are three levels of the pelvic cavity, each with differing diameters. The longest diameter of the fetal head (anteroposterior) must rotate to fit the longest diameter of the birth canal:
- Pelvic inlet – transverse diameter
- Mid-pelvic cavity – oblique diameter
- Pelvic outlet – anteroposterior diameter
|Anterior pelvis –
||Posterior pelvis –
||* Sacrospinous (to ischial spine)
Divide the notches into greater and lesser sciatic foramen
Pelvic diaphragm (floor) – consists of the levator ani (pubococcygeus, iliococcygeus, puborectalis) and (ischio)coccygeus muscles. It separates the pelvic cavity above from the perineal region below.
- Ischiococcygeus extends from the ischial spine to sacrum and coccyx
- Pubococcygeus extends from pubis and anterior obturator internus
- Puborectalis is inferior to these muscles, forming a sling from pubis around the anorectal junction
Piriformis and obturator internus form the lateral walls of the pelvic cavity.
Pelvic outlet musculature – the outlet is diamond shaped, and is made up of two triangles: Urogenital triangle (diaphragm) – is inferior to the pelvic diaphragm, anterior only.
- Deep layer – sphincter urethrae (encircling urethra), deep transversus perinei (posterior)
- Superficial layer – superficial transverse perinei, bulbospongiosus (covering bulb of the vestibule/penis), ischiocavernosus (covering crura of the clitoris/penis)
These structures lie in the superficial perineal space.
The perineal body (tendinous centre of the perineum) is a central anchor point for many muscles; located between the vagina/urethra and anus.
Ischioanal triangle, contains the ischiorectal fossa (the space below the pelvic diaphragm, mainly posterior to the urogenital diaphragm). It is bounded laterally by the ischiopubic ramus, obturator internus and sacrotuberous ligament, and contains the anal canal, external anal sphincter, pundendal nerve and interior pudendal vasculature. It is filled with fat that is liquid at body temperature – this is important as it allows spread of infection, as well as dilation of the anorectal canal during defecation.