Obstetrics and Gynaecology chapters
Female genital anatomy: organs, ligaments, blood supply, lymphatics and nerves
The vulva, vagina, uterus, cervix, tubes and ovaries, the ligaments that hold them, and the arteries, veins, lymph nodes and nerves of the female genital tract, with the surgical relations PGET likes to test.
- The uterus is normally anteverted and anteflexed, about 7.5 cm long; the cervix is about 2.5 cm and the ureter passes roughly 1 cm to its side, below the uterine artery.
- The cardinal and uterosacral ligaments support the uterus; the broad ligament is only a peritoneal fold; the round and ovarian ligaments are remnants of the gubernaculum.
- The ovarian artery arises from the aorta; the left ovarian vein drains to the left renal vein; ovary and tube drain to para-aortic nodes, vulva and lower vagina to inguinal nodes; the pudendal nerve (S2-S4) supplies the perineum.
On this page
Overview
The female genital tract has two parts:
- External genitalia (vulva): mons pubis, labia majora and minora, clitoris, vestibule and the vestibular (Bartholin's) glands.
- Internal organs: vagina, uterus with cervix, two fallopian tubes and two ovaries.
These organs lie in the pelvis close to the bladder, ureters and rectum. Most exam questions test the relations (especially the ureter), the ligaments, the source of each artery, and where the lymph goes, because these explain surgical injury and the spread of cancer.
External genitalia (vulva)
| Structure | Key facts |
|---|---|
| Mons pubis | Pad of fibrous tissue and fat over the pubic bone, covered by hairy skin |
| Labia majora | Skin folds with fat; sebaceous, sweat and some apocrine glands; the round ligament ends in the fat here |
| Labia minora | Thin folds with sebaceous glands but no fat; in front they split to form the prepuce and frenulum of the clitoris, behind they join as the fourchette |
| Clitoris | Erectile tissue (paired corpora cavernosa continuing as the crura); about 0.5-3.5 cm long |
| Vestibule | Area between the labia minora; receives the urethra, vagina and Bartholin's ducts |
| Bartholin's glands | Pea-sized, one each side, posterolateral; each opens by a duct of about 2 cm into the vestibule just outside the hymen; they add lubrication |
| Hymen | Thin mucosal fold at the vaginal entrance, usually perforated; tags left after rupture are carunculae myrtiformes |
Bartholin's glands lie posterolaterally at the vaginal opening. A new solid swelling here in an older woman should be biopsied, not just drained, to exclude cancer.
Vagina
- A fibromuscular tube lined by stratified squamous epithelium; it has no glands. It is kept moist by cervical mucus and transudate.
- Posterior wall is longer (about 9 cm) than the anterior wall (about 7 cm), because the cervix enters through the upper anterior wall.
- The vault around the cervix forms four fornices: anterior, posterior and two lateral. The posterior fornix is the deepest.
- Shape: the mid-vagina is a transverse slit; the lower vagina is H-shaped in cross-section.
- pH about 4.5: oestrogen fills the cells with glycogen; Döderlein's lactobacilli turn it into lactic acid. Before puberty and after menopause there is little glycogen and the pH is higher.
Relations of the vagina
| Wall | Relation |
|---|---|
| Anterior | Base of bladder above, urethra below (fused to the lower anterior wall) |
| Posterior, upper part | Pouch of Douglas (peritoneum) |
| Posterior, middle third | Rectum, separated by the rectovaginal fascia |
| Posterior, lower third | Perineal body |
| Lateral | Cardinal ligaments and ureter at the lateral fornix; levator ani and ischioanal fossa lower down |
The posterior fornix touches the pouch of Douglas, so blood or pus in the pouch can be felt or drained through it, and a prolapsed ovary may be felt there.
Uterus
- Hollow, thick-walled, pear-shaped organ: adult size about 7.5 cm long, 5 cm wide, 3 cm thick, weight about 70 g.
- Parts: fundus (above the tubes), body (corpus), cornua (where tubes enter), isthmus (narrow part above the cervix, which forms the lower segment in pregnancy) and cervix.
- Position: the long axis of the uterus makes roughly a right angle with the vagina and tilts forward (anteversion); the body also bends forward on the cervix at the isthmus (anteflexion). About 20% of women have a retroverted uterus, which is normal unless it is fixed (think endometriosis or adhesions).
- Layers: serosa (peritoneum), myometrium (bulk; interlacing smooth muscle, with a middle layer of crossing fibres that clamp vessels after delivery) and endometrium (columnar epithelium with tubular glands).
- Age changes: after birth, loss of maternal oestrogen shrinks the uterus; through childhood the cervix is longer than the body; adult shape is reached in the late teens; after menopause it atrophies.
Internal os: anatomical and histological
The anatomical internal os is the narrowing where the body meets the cervix. The histological internal os is lower, where the lining changes from endometrium to endocervical mucosa. The isthmus lies between them.
Cervix
- About 2.5 cm long; the part above the vagina is supravaginal, the part in the vagina is the ectocervix (portio vaginalis).
- Upper cervix has more smooth muscle; the lower cervix is mainly fibrous tissue.
- Endocervix: columnar, mucus-secreting epithelium in branching folds (arbor vitae), with deep glands that make clear alkaline mucus (the main source of normal discharge).
- Ectocervix: stratified squamous. The meeting point is the squamocolumnar junction, the site of the transformation zone and of cervical cancer.
- Parametrium (loose connective tissue) lies at the side; the ureter passes roughly 1 cm to the side of the supravaginal cervix.
Fallopian (uterine) tubes
- About 10 cm long, running in the upper edge of the broad ligament (mesosalpinx).
- They open into the peritoneal cavity, so the cavity is connected to the outside through uterus and vagina (route for ascending infection).
| Part (medial to lateral) | Feature |
|---|---|
| Interstitial (intramural) | Inside the uterine wall; ectopic here ruptures late and bleeds heavily |
| Isthmus | Narrow, thick-walled; site of sterilisation clips |
| Ampulla | Widest and longest; usual site of fertilisation and of most tubal ectopic pregnancies |
| Infundibulum | Funnel with fimbriae; one long ovarian fimbria reaches the ovary |
- Muscle: inner circular, outer longitudinal. Mucosa forms longitudinal folds (plicae) with ciliated and secretory cells; there is no submucosa and no glands.
About 98% of ectopic pregnancies are tubal (Gynaecology by Ten Teachers), and the ampulla is the usual tubal site.
Ovaries
- Almond-shaped; adult size about 3 x 1.5 x 1 cm; small in childhood, shrunken and wrinkled after menopause.
- Lie in the ovarian fossa on the side wall, bounded by the external and internal iliac vessels; the ureter runs behind, and the obturator nerve and vessels run along the side wall nearby.
- Attachments:
- Mesovarium: joins the ovary to the back of the broad ligament; vessels enter at the hilum.
- Ovarian ligament: from the ovary to the uterine cornu.
- Suspensory (infundibulopelvic) ligament: from the ovary to the side wall; carries the ovarian vessels, lymphatics and nerves.
- The surface has a single layer of cuboidal cells (germinal epithelium), not true peritoneum. Ten Teachers stresses that the ovary is the only abdominal organ not covered by peritoneum.
Because the ovarian vessels run close to the tube, removing a tube (salpingectomy) can damage the ovarian blood supply and reduce ovarian reserve.
Ligaments and fascial supports
| Ligament | Course | Role |
|---|---|---|
| Broad ligament | Double fold of peritoneum from the side of the uterus to the pelvic wall | Not a true support; carries vessels, nerves, lymphatics |
| Cardinal (transverse cervical, Mackenrodt's) | Fan-shaped bands from cervix and vault to the side wall | Main support of uterus and vaginal vault |
| Uterosacral | From cervix and vault back to the sacrum, almost vertical when standing | Supports the cervix; holds it back |
| Pubocervical | Cervix to pubis under the bladder | Supports the bladder base |
| Round ligament of uterus | Cornu, forwards under the anterior leaf, through the inguinal canal to the labium majus | Helps keep the fundus forward |
| Ovarian ligament | Ovary to cornu, below the tube | Holds the ovary to the uterus |
Contents of the broad ligament
- Fallopian tube (upper edge) and mesosalpinx
- Ovarian ligament and round ligament
- Uterine and ovarian vessels, lymphatics, nerves
- Ureter attached to its posterior leaf near the base
- Parametrium (loose tissue at the base)
- Mesonephric remnants: epoophoron, paroophoron and Gartner's duct
One cord, two ligaments: the gubernaculum is a single cord broken at the cornu; its upper half is the ovarian ligament and its lower half is the round ligament (in males it pulls the testis into the scrotum).
Blood supply
Arteries
| Artery | Origin and course | Supplies |
|---|---|---|
| Uterine | Anterior division of the internal iliac; runs medially in the base of the broad ligament, crosses above the ureter beside the cervix, then climbs tortuously up the side of the uterus to join the ovarian artery | Uterus, cervix, upper vagina, a branch to the ureter |
| Ovarian | Abdominal aorta just below the renal arteries; runs down on psoas, crosses in front of the ureter at the pelvic brim, enters the infundibulopelvic ligament | Ovary and tube; joins the uterine artery |
| Vaginal | Internal iliac (anterior division), at a lower level | Vagina |
| Internal pudendal | Internal iliac; leaves through the greater sciatic foramen, winds round the ischial spine, runs in the pudendal (Alcock's) canal | Inferior rectal, perineal and clitoral branches; vulva |
| Superior rectal | Continuation of the inferior mesenteric artery | Rectum |
- The internal iliac artery is about 4 cm long and starts at the common iliac bifurcation in front of the sacroiliac joint. The branches to the pelvic organs come from its anterior division.
- The ovary has a dual supply: ovarian artery plus the ovarian branch of the uterine artery.
"Water under the bridge": the ureter (water) passes under the uterine artery (bridge) beside the cervix. Clamping the uterine artery at hysterectomy is the classic moment of ureteric injury.
Veins
- Pelvic veins form plexuses round the bladder, uterus, vagina and rectum that drain mainly to the internal iliac veins.
- The ovarian veins start in the pampiniform plexus in the broad ligament. The right ends in the inferior vena cava; the left ends in the left renal vein.
The left ovarian vein joins the left renal vein at a right angle and is more prone to reflux, which is why pelvic congestion and varices are more common on the left.
Lymphatic drainage
| Region | First nodes |
|---|---|
| Vulva and perineum | Superficial inguinal, then deep femoral (largest is the node of Cloquet) and external iliac |
| Lower third of vagina | Superficial inguinal (like the vulva) |
| Upper two-thirds of vagina | With the cervix |
| Cervix | Parametrial, obturator, internal iliac and external iliac; also common iliac, sacral and para-aortic |
| Body of uterus | Mostly with the cervix; fundus along ovarian vessels to para-aortic; a few along the round ligament to inguinal nodes |
| Ovary and tube | Along the infundibulopelvic ligament to the para-aortic nodes (near the renal vessels) |
| Lower urethra | With the vulva (inguinal) |
All pelvic lymph finally reaches the cisterna chyli (about L2) and the thoracic duct.
Ovarian cancer can spread to para-aortic nodes without pelvic node disease, because the ovary developed high on the back wall and its lymph follows the ovarian vessels.
Nerve supply
Vulva and perineum
- Pudendal nerve (S2, S3, S4): passes behind the ischial spine; gives the inferior rectal nerve, the perineal nerve (vulval skin, superficial perineal muscles, part of levator ani) and the dorsal nerve of the clitoris (sensory).
- Front of the vulva and mons: ilioinguinal and genitofemoral nerves (L1).
- Posterior perineum: posterior femoral cutaneous nerve.
- Levator ani: mainly S3 and S4.
Pelvic organs
- Sympathetic: aortic plexus → superior hypogastric plexus (the so-called presacral nerve, in front of the last lumbar vertebra) → inferior hypogastric (uterovaginal, Frankenhäuser's) plexus beside the cervix.
- Parasympathetic: pelvic splanchnic nerves from S2-S4 join the uterovaginal plexus.
- Ovary: from the ovarian plexus travelling with the ovarian vessels, not from the pelvic plexuses.
"S2, 3, 4 keeps the pelvis off the floor" (pudendal and pelvic splanchnic nerves).
Expect: uterus size, anteversion and anteflexion, and when retroversion matters; the anatomical and histological internal os; the squamocolumnar junction; parts of the tube, the ampulla as the site of fertilisation and ectopic pregnancy, the isthmus for sterilisation; ovarian attachments and the ovary lacking a peritoneal cover; the cardinal ligament as the main support and the broad ligament as a fold; the round and ovarian ligaments from the gubernaculum; ureter under the uterine artery 1 cm lateral to the cervix; ovarian artery from the aorta and left ovarian vein to the left renal vein; lymph of ovary to para-aortic and of vulva and lower vagina to inguinal nodes; the pudendal nerve (S2-S4) and pudendal block at the ischial spine.
Quick revision
- Uterus 7.5 x 5 x 3 cm, 70 g; anteverted and anteflexed; 20% retroverted.
- Cervix 2.5 cm; ureter 1 cm lateral, under the uterine artery.
- Tube 10 cm: interstitial, isthmus, ampulla (fertilisation, ectopic), infundibulum.
- Cardinal + uterosacral = main supports; broad ligament = peritoneal fold.
- Gubernaculum → ovarian ligament + round ligament (ends in labium majus).
- Ovarian artery from aorta; left ovarian vein → left renal vein.
- Lymph: ovary → para-aortic; cervix → pelvic side wall; vulva and lower vagina → inguinal.
- Pudendal nerve S2-S4; ovary has its own ovarian plexus.
Written by The House Job from standard references (Gynaecology by Ten Teachers; Obstetrics by Ten Teachers; Snell's Clinical Anatomy).
FAQ
Why is the ureter at risk during hysterectomy?
It lies roughly 1 cm from the side of the cervix, passing beneath the uterine artery and close to the lateral fornix, so it can be clamped, cut or lose its blood supply when the uterine vessels and vault are secured.
Is the broad ligament a support of the uterus?
No. It is a double fold of peritoneum that carries vessels and nerves; the real supports are the cardinal and uterosacral ligaments with the pelvic floor.
Why does ovarian cancer reach the para-aortic nodes early?
The ovary forms high on the back wall of the abdomen and keeps its vessels from the aorta, so its lymph runs up with the ovarian vessels to the para-aortic nodes.
What is the clinical meaning of a retroverted uterus?
A mobile retroverted uterus is a normal variant; a fixed one suggests adhesions from endometriosis or pelvic infection.