33. The anatomy and development of the female external genital organs. The histology of the vagina.

Anatomy:The anatomy of  the female external genital organs.

Vulva (female external genital organs)

Similar to male genital organs except:

• vagina pierces UG diaphragm
• urethra associates w/ ant wall of vagina
• genital folds do not unite @ midline –> instead forms vestibule
• bulbus does not unite @ midline

Vulva is made up of:

1. mons pubis
2. labia majora
3. labia minor
4. clitoris
5. vestibule
6. bulbus vestibuli
7. greater vestibular glands
8. vaginal orifice
9. ext. urethral orifice

Mons Pubis:

• rounded elevation of pubic area above symphysis
• subcutaenous CT – inc @ puberty, dec w/ menopause
• covered w/ pubic hair = secondary sexual sign (maturity)

Labia Majora:

• external covering of the vestibule
• contain fat as well, and smooth m bundles
  
• also covered w/ hair
• L & R join @ ant/post commissure – post usually disappears after having a child
  
• bulb of vestibule and glands below them
• round ligament inserts here after emerging from inguinal canal
• outer surface is covered w/ pigmented skin w/ many sebaceous glands
  

Labia Minora:

• small hairless folds w/in labia minora
• enclose the vestibule directly
• united posteriorly via frenulum of labia minora, clitoris
  
• unites ant to form prepuce of clitoris
• contain bulbospongiosus m
• high # of nerve endings = primary erogenic organ

Clitoris (homologus to male penis)
a) Root

• crura of clitoris originate from inf ramus of pubis
• ischiocavernosus m covers the crura
• L & R crus join @ midline and angle down to form body

b) Body

• suspended from pubis symphysis via suspensory ligament
• made from union of corpora cavernosa

c) Glans

• made from corpora cavernosum
• under cover of prepuce when flaccid
• protrudes when erected
• rich in n endings –> stimulate for orgasm

Vestibule

• space enclosed by labia minora
• has ext urethral orifice
• openings of paraurethral glands
  
• contains openings of vagina, urethra, and greater vestibular glands

Bulbus vestibuli (analogous to bulb of penis, corpus spongiosum)

• don’t unite @ midline
• separated by vagina
• become erect during sexual excitement = erectile tissue
  
• open labia minora
• bulbospongiosus m. covers bulb

Vaginal orifice

• located @ post part of vestibule
• behind ext opening of urethra
• Hymen closes off vaginal opening, leaves an opening, breaks during 1st sexual intercourse

Ext urethral orifice

• small opening @ ant part of vestibule
• just in front of ant wall of vagina
• 2-3 cm post to clitoris
• contains ducts of paraurethral glands (analogous to prostate) – will secrete the female ejaculate
  

Greater vestibular glands

• @ post end of bulb of vestibule
• behind vaginal orifice
• open @ side of labia minora
• secrete lubricant (mucus) during sexual excitement
• also surrounded by bulbospongiosus m
  
• lubricate vaginal orifice for penetration

Blood supply:

• ext pudendal a (femoral a) – supplies skin
• int pudendal a (int iliac a) – skin , sexual organs, perineal muscle
  
  • labial a
  • deep dorsal a of  clitoris
    
• drained by int pudendal v

Lymph Drainaga: superficial inguinal lymph nodes

Nerve supply:

• Ilioinguinal n (lumbar plexus)
• genital br of genitofemoral n (lumbar plexus)
• pudendal n
• cut br of femoral n

PNS = inc vaginal secretion, excitation of clitoris, erection for tissue in bulbs of vestibule

Vagina:

Function = organ of copulation & birth

• excretory duct for menstrual blood
• inf part of birth canal
• participates in sexual intercourse

General Info:

• runs  from cervix of uterus –> vestibule
• 7-9 cm, usually flat
• has transverse folds, which flatten during sex to accomadate penis = rugae
• 30-40 degrees back from vertical plane
• opens into vestibule of vulva
• opening partially closed off by hymen

• upper end divided into 4 fornices = 1 ant, 1 post, 2 lat that surround vaginal portion of cervix
  • ant fornix = shallowest, touches fundus of bladder
  • post fornix = deepest and touches rectouterine pouch, covered w/ peritoneum of rectum post
  • lat fornix = uterus, uterine a/v – w/in broad lig of uterus

Various Views of Vagina - Topography, internal structure, etc

Topography:

• ant = urethra in urethrovaginal septum, space b/w vagina and septum = urethrovaginal space
• post = loops of SI (sup), rectum via rectovaginal septum
• lat = contact cervix of uterus (sup)
• inf = levator ani m, UG diaphragm, perineal body

supported by:

• upper part = levator ani m, transverse cervical lig, pubocervical lig, sacrocervical lig
  
  • (ligaments together = paracolpium of vagina)
  • fibers merge w/ fibers of paraproctium(post) and paracysticum (ant)
• middle part = UG diaphragm
• lower part = perineal body

Blood supply:

• vaginal a (uterine a)
• vaginal br of int pudendal a (inf part of vagina), middle rectal a (middle part of vaginal), int iliac a

Venous drainage = vaginal venous plexus –> pelvic venous plexus –> int iliac v

Lymph Drainage:

• Sup part = int/ext  iliac l.n.
• Mid part = int iliac l.n
• Inf part = sacra and common iliacn l.n., superficial inguinal l.n.
  

Nerve supply: for autonomic innervation see topic # 40

• Inf hypogastric plexus
• pelvic splanchnic n

Minimals for this topic:

<!– @page { margin: 0.79in } P { margin-bottom: 0.08in } –>

208. Define the visceral relations of the vagina?

• The vagina is related anteriorly to the uterus and bladder and is fused with the urethra. Posteriorly, the vagina is related to the recto-uterine pouch, the rectum and the perineal body. The lateral fornix of the vagina is related to the ureter and uterine artery. At its upper aspect the vagina fuses with the uterus, so that it encloses the vaginal part of the cervix.

Slide #75 Vagina *H&E

Stuctures to Identify:

• str squamous non keratinized epithelium
• LP
• 2 muscular layers
• adventia, with n/possible ganglia and sk. musc

* So if you see a thick epithelium that fades from pink to white as u move up = VAGINA

General Info:

• no glands here – all lubrication done by cervical glands and Bartholin’s glands at entrance
• epithelium thickens and secretes glycogen under influence of estrogen
• Vaginal bacteria changes the glycogen into lactic acid — acidity protects the vaginal canal from pathogens

Epith

• is very characteristic of vagina
  
• THICK,  str squamous epithelium  with mucosal folds
• has Langerhan’s cells @ base
  
• CT papilla coming up from under lying LP
• very faint because very rich in glycogen, which can be washed away in slide prep.
  

Vaginal pale epithelium, notice the lymphocytes and Langerhan's cells at base of epith, as well as CT papilla

LP

• aka semi cavernous tissue = b/c a/v similar to cavernous tissue of penis
• dense reg CT filled with elastic tissue for stretching of vaginal wall
• MALT, lymph nodules, a/v
• underlying submucosa interweaves with it
• no definitve border between LP and submucosa = NO muscularis mucosae

Muscular Layer

• Inner longitudinal layer, outer oblique layer

Adventia

• lots of a/v and n bundles
• may have PNS ggl
• May have skeletal m fibers from perineal m – not part of vagina, just attached to wall of it