anatomy of female external genitalia

1. ANATOMY OF GENITAL
TRACT
BY DR. ESHNA GUPTA

2. The anatomy of female genital
tract is divided into :
 EXTERNAL GENITALIA
 INTERNAL GENITALIA
 ACCESSORY REPRODUCTIVE ORGANS

3. EXTERNAL GENITALIA
(vulva ; pudendum)
The vulva includes the structures visible externally from
the symphysis pubis to the perineal body.
Bounded
Anteriorly : by mons pubis
Laterally : by thighs
Posteriorly : by perineum

4. VULVA includes
• Mons pubis
• Labia majora
• Labia minora
• Clitoris
• Hymen
• Vestibule
• Urethral opening
• Greater vestibular or Bartholin’s glands
• Minor vestibular glands
• Paraurethral glands

5. MONS PUBIS
• Triangular mound of subcutaneous
adipose connective tissue that
covers the pubic bone.
• Growth of curly hair on the mons
pubis after puberty forms the
escutcheon.
• Hair is distributed in a triangle,
whose base covers the upper
margin of symphysis pubis and tip
ends at the clitoris.

6. LABIA MAJORA
• They are 7 to 8 cm in length,
2 to 3 cm in depth, and 1 to
1.5 cm in thickness.
• They are continuous directly
with the mons pubis
superiorly.
• Posteriorly, taper and merge
into the area overlying the
perineal body to form the
posterior commissure.
Posterior
commissure

7. • The outer surface of the labia majora is covered with
hair.
• Inner surface has abundant apocrine and eccrine
sweat and sebaceous glands and is hairless.
• The labia majora are covered by squamous
epithelium.
• Beneath the skin, dense connective tissue and
adipose tissue are present which are supplied with a
rich venous plexus.
• Nearly void of muscular elements.
• Homologous with the scrotum in males.

8. • It contains the termination of round ligament of uterus at
its distal third and the obliterated processus vaginalis
(canal of nuck).
• The round ligament can give rise to leiomyomas in this
region.
• Obliterated processus vaginalis can be seen as dilated
embryonic remanant in adults.
• During pregnancy, this vasculature commonly develops
varicosities, especially in parous women, from increased
venous pressure created by advancing uterine weight.
• May form haematoma if ruptured during childbirth.

9. LABIA MINORA
• Each is a thin fold of tissue, lying medial to each labia
majora.
• Length : 2-10 cm
Width : 1-5 cm
• Extend superiorly, where each divides into two
lamellae. The lower pair fuses to form the frenulum
of the clitoris, and the upper pair merges to form the
prepuce.
• Inferiorly, extend to approach the midline as low
ridges of tissue that fuse to form the fourchette
(lacerated during childbirth).

11. • Structurally, the labia minora are composed of
connective tissue with many vessels, elastin fibers,
and some smooth muscle fibers.
• They are supplied with a variety of nerve endings.
• There are many sebaceous glands, but lack hair
follicles.

12. The lateral portion of
the inner surface is
covered by stratified
squamous epithelium to
a demarcating line—
The Hart line.
Medial to this line, each
labium is covered by
squamous epithelium
that is nonkeratinized.

13. • Cutaneous structures lie on a connective tissue
stratum, that is loosely organised and thus permits
mobility of skin during coitus.
• This loose attachment allows skin to be easily
dissected off the underlying fascia during skinning
vulvectomy in that area.
• Homologous to the ventral aspect of penis.

14. CLITORIS
• This principal female erogenous organ is located
beneath the prepuce and above the urethra.
• It projects downward between the branched
extremities of the labia minora, and the free end
points downward and inward toward the vaginal
opening.
• The clitoris rarely exceeds 2 cm in length and is
composed of a glans, a corpus or body, and two
crura.

15. • The glans is usually less than 0.5 cm in diameter, is
composed of spindle-shaped cells, and is covered by
stratified squamous epithelium that is richly
innervated.
• The clitoral body contains two corpora cavernosa.
Extending from the clitoral body, each corpora
cavernosa diverges laterally to form the long, narrow
crura. These lie along the inferior surface of the
ischiopubic rami and deep to the ischiocavernosus
muscles.
• Attached to the undersurface of pubic symphysis by
suspensory ligament.

17. • Homologous to penis in males.
• Clitoromegaly : Length > 3.5 cm and Width > 1 cm.
Occurs in virilism (due to excess androgens).
• Injury causes profuse bleeding and intense pain.
• BLOOD SUPPLY
From branches of Internal Pudendal Artery
Clitoral body : Deep Artery of the clitoris
Glans & prepuce : Dorsal artery of clitoris

18. VESTIBULE
• In adult women, it is an
almond-shaped area that is
enclosed by
o Hart line laterally,
• External surface of the hymen
medially,
• Clitoral frenulum anteriorly,
• Fourchette posteriorly.

19. • The vestibule usually is perforated by six openings:
the urethra, the vagina, two Bartholin gland ducts,
and at times, two ducts of the largest paraurethral
glands—the Skene glands.
• The posterior portion of the vestibule between the
fourchette and the vaginal opening is called the fossa
navicularis. It is usually observed only in nulliparous
women.

21. • URETHRAL OPENING
Situated in front of vaginal
opening, 1-1.5 cm below the pubic
arch.
The paraurethral glands open
either on the posterior wall of the
urethral orifice or directly into the
vestibule.

22. VAGINAL OPENING & HYMEN
• Lies at the posterior end of vestibule.
• The vaginal opening is rimmed distally by the hymen
or its remnants.
• It is composed mainly of elastic and collagenous
connective tissue, and both outer and inner surfaces
are covered by stratified squamous epithelium.

23. • In pregnant women, the epithelium of the
hymen is thick, and the tissue is rich in
glycogen.
• Changes produced in the hymen by childbirth
are usually readily recognizable.
• Over time, the hymen consists of several
nodules of various sizes, also termed hymenal
caruncles.

25. VESTIBULAR GLANDS
BARTHOLIN’S GLANDS
• Termed greater vestibular glands, are the major
glands.
• Measure 0.5 to 1 cm in diameter, yellowish white in
colour.
• Lie inferior to the vestibular bulbs and deep to the
inferior end of the bulbo cavernosus muscle on
either side of the vaginal opening.

27. • Their ducts are 1.5 to 2 cm long and open distal to
the hymenal ring at 5 and 7 o’clock on the vestibule
at the junction of the anterior two third and
posterior one third.
• The duct is lined by columnar epithelium and
stratified squamous epithelium near its opening.
• Compound racemose variety.
• Homologous to bulbo urethral gland of male.

28. • During sexual excitement it secretes abundant
alkaline mucus which helps in lubrication.
• Following trauma or infection, either duct may
swell and obstruct to form a cyst or abscess.

29. • MINOR VESTIBULAR GLANDS
Shallow glands lined by simple mucin
secreting epithelium and open along the Hart
line.

30. PARAURETHRAL GLANDS
• Collective arborization of glands whose ducts open
predominantly along the entire inferior aspect of the
urethra.
• The two largest are called Skene glands, and their
ducts typically lie distally near the urethral meatus.
• Inflammation and duct obstruction of any of the
paraurethral glands can lead to urethral diverticulum
formation.
• Homologous to prostate in males.

32. VESTIBULAR BULBS
• These are almond-shaped aggregations of veins, 3 to
4 cm long, 1 to 2 cm wide, and 0.5 to 1 cm thick.
• Lie beneath the bulbocavernosus muscle on either
side of the vestibule in front of the bartholin’s
glands.
• Homologous to the single bulb of the penis and
corpus spongiosum in the male.
• Likely to be injured during childbirth and may even
rupture to create vulvar hematoma.

34. BLOOD SUPPLY
• ARTERIES
Branches of INTERNAL PUDENDAL ARTERY
 Labial
Transverse perineal
Artery to the vestibular bulb
Dorsal arteries to clitoris
Branches of FEMORAL ARTERY
Superficial & Deep external pudendal

36. • VEINS
Internal pudendal vein
Vesical or Vaginal venous plexus
Long saphaneous vein
Varicosities may develop during pregnancy and may
rupture spontaneously causing visible bleeding or
hematoma.

37. NERVE SUPPLY
Bilateral spinal somatic nerves
• Anterio-superior part –
by Cutaneous branches from ilioinguinal &
genital br. Of Genitofemoral Nerve (L1 & L2 )
• Posterio-inferior part –
by Pudendal branch from posterior cutaneous
nerve of thigh (S123)
Between these two vulva supplied by Labial &
Perineal branch of Pudendal Nerve (S234).

39. LYMPHATICS OF VULVA
• Labia Majora (Anterior half)
Lymphatics intercommunicate with the opposite side
in the region of mons veneris → Superficial inguinal
nodes
• Labia majora (Posterior half)
Drains into Superficial inguinal → Deep inguinal →
External iliac

40. • Labia Minora and Prepuce of Clitoris
intercommunicate with lymphatics of opposite
side in vestibule → Superficial inguinal nodes.
• Glans of clitoris
Drain directly into deep inguinal and external iliac
nodes.
• Bartholin’s glands
Drain into superficial inguinal and anorectal
nodes.

42. URINARY BLADDER
• Hollow muscular organ.
• Capacity : 450 ml ; can retain 3-4 liters of urine.
• Ovoid shape when distended.
• Tetrahedral in shape when empty and has :
(a) a base or fundus (directed backwards)
(b) a neck (lowest and most fixed part)
(c) three surfaces : superior, right, left inferolateral
(d) four borders : two lateral , one anterior, one
posterior

44. • A full bladder is ovoid in shape and has :
(a) an apex (directed upwards towards umbilicus)
(b) a neck (directed downwards)
(c) two surfaces – anterior and posterior

45. RELATIONS
• APEX : connected to umbilicus by median umbilical
ligament (obliterated urachus).
• BASE : related to uterine cervix and vagina.
• NECK : lies 3-4cm behind the lower part of pubic
symphysis, pierced by the internal urethral orifice,
related to pelvic fascia surrounding upper part of
urethra.

46. • SUPERIOR SURFACE : peritoneum covers greater part
except for a small area near posterior border related
to supravaginal portion of cervix.
• INFEROLATERAL SURFACES : devoid of peritoneum,
related to pubovesical ligament, levator ani,
obturator internus.

47. • TRIGONE
- Small triangular area over
lower part of base of
bladder.
- Its apex is directed
downwards and forwards.
- The internal urethral
orifice opens here.
- Ureters open at its
postero-lateral angles.

48. STRUCTURES
From outside inwards :
• Outer visceral layer of the pelvic fascia
• Detrusor muscle
• Mucous coat is lined by transitional epithelium with
no glands.
• There is no submucous coat.

50. BLOOD SUPPLY
• ARTERIAL
Superior and inferior vesical arteries
• VENOUS
Drain into vesical and vaginal plexus → internal iliac
veins
• LYMPHATICS
External and internal iliac lymph nodes

51. URETHRA
• Extends from bladder neck to the external urethral
meatus.
• 4 cm in length and 6 mm in diameter.
• Bladder forms an angle with the posterior wall of
urethra called POSTERIOR URETHROVESICAL ANGLE
(100°).
• Runs downwards and forwards in close proximity with
anterior vaginal wall.
• About 1 cm from the lower end, pierces the Triangular
ligament, opening into vestibule 2.5 cm below the
clitoris.

52. RELATIONS
• POSTERIORLY : anterior vaginal wall.
• ANTERIORLY : posterior aspect of pubic symphysis.
Lower one third is attached to pubic rami by fibrous
tissue on each side - PUBOURETHRAL LIGAMENT
(prevents hypermobility of bladder neck and
urethra).
• LATERALLY : passes through triangular ligament ,
surrounded by Compressor urethrae.

53. • GLANDS
The Paraurethral glands open into the lumen.
The largest, Skene’s glands open either on the
posterior wall just inside the external urethral
meatus or into the vestibule.

54. SPHINCTERS
• LISSOSPHINCTER
It is an intricate decussation of the involuntary
muscles forming anterior and posterior slings
forming involuntary internal sphincter at the
urethro-vesical junction.
• SPHINCTER URETHRA (in the urogenital diaphragm)
Allows voluntary arrest of urine flow.
• ACCESSORY EXTERNAL SPHINCTER
Bulbocavernosus, ischiocavernosus.

55. FUNCTIONALLY
Urethra is divided into 3 parts
• Proximal urethra
-Weakest part.
- Inner longitudinal muscle of detrusor fades out in
this part.
- Fails to withstand the rise of intra vesical or intra
abdominal pressure.

56. • MIDURETHRA
- Strongest part.
- Support by intrinsic striated muscle :
Rhabdosphincter urethrae, slow twitch fibres
For urethral closure at rest.
- Extrinsic muscle: Levator ani
First twitch fibres, for support to urethra on stress.

57. • Distal urethra
Passive conduit
Surrounded by collagen tissue.

58. STRUCTURES
• Mucous membrane is lined by transitional epithelium
except at external urethral meatus -- stratified
squamous epithelium.
• Submucous coat is vascular.
• Muscle coat is composed of involuntary muscles and
the fibres are arranged in the form of crossed spirals.

59. BLOOD SUPPLY
• ARTERIAL
Proximal part by inferior vesical branch.
Distal part by a branch of internal pudendal artery.
• VENOUS
Drain into vesical plexus and internal pudendal veins.
• LYMPHATICS
Drain into hypogastric glands → external iliac lymph
nodes.

60. SUPPORT TO BLADDER NECK AND
URETHRA
• INTRINSIC FACTORS :
(i) Intrinsic rhabdosphincter urethrae
(ii) Urethral submucosal venous plexus
(iii) Urethral smooth muscles
(iv) Sympathetic activity
(v) Estrogen to increase collagen tissue

61. • EXTRINSIC FACTORS :
(i) Contraction of pubococcygeus
(ii) Pubourethral ligaments
(iii) Exercise

62. NERVE SUPPLY OF VESICOURETHRAL UNIT

63. APPLIED ANATOMY
• Because of shortness and close proximity of urethra
to vagina and anus, infection is likely and commonly
spreads upwards to involve the bladder.
• Because of close proximity to vagina, urethra may get
injured during childbirth.
• Paraurethral glands are sites of infection and
development of adenoma or malignant changes can
occur.
• Urinary incontinence.