C27 - Vagina, female urethra, blood supply and innervation

Question 1

Structures to mention

Answer 1

Vagina:

• Fornix vaginae (Cranial blind pouch of vagina, surrounding the portio vaginalis cervicis)
• Hymen (Fold of mucosa just cranial to the transverse plane of the urethral orifice)
• Ostium vaginae (Opening of the vagina into vestibulum vaginae)

Vestibulum vaginae:

• Bulbus vestibuli (eq, ca) (Cavernous tissue in the lateral wall of the vestibule)
• Diverticulum suburethrale (su, Ru) (Blind sac ventral to the urethra and opening into the urethral orifice)
• Tuberculum urethrale (ca) (Elevation bearing the urethral orifice)

Vulva:

• Labium vulvae (Lip of vulva)
• Rima vulvae (Pudendal fissure between right and left labia. External urogenital opening)

Clitoris:

• Crus clitoridis (Right and left crura are attached to arcus ischadicus and join corpus clitoris)
• Corpus clitoridis (Composed of the fused corpora cavernosa)
• Glans clitoridis (Best developed in ca and eq)
  
  • Sinus clitoridis (eq)
  • Frenulum clitoridis (ca, eq)
• Preputium clitoridis (Prepuce of clitoris)
• Fossa clitoridis (eq, ca) (Preputial cavity)
• Corpus cavernosum clitoridis (Right and left corpus cavernosus are fused to form corpus clitoridis)
• Corpus spongiosum glandis (ca, eq) (Continuous with the pars intermedia bulborum)

Urethra feminina:

• Ostium urethrae externum
• Crista urethralis (Dorsal longitudinal mucosal ridge extending from the junction of the plica uretericae caudally to the middle of the urethra)

Muscles:

• M. bulbospongiosus (Divided into 2 parts in female)
  
  • ​M. constrictor vestibuli
  • M. constrictor vulvae (In labium. O: spf. part of m. sphincter ani externus)
• M. ischocavernosus (O: Arcus ischiadicus. Rudimentary in female)

Question 2

Interspecies differences

Answer 2

Vestibulum vaginae:

• Bulbus vestibuli (eq, ca)
• Diverticulum suburethrale (su, ru)
• Tuberculum urethrale (ca)

Clitoris:

• Glans clitoridis
  
  • Sinus clitoridis (eq)
  • Frenulum clitoridis (ca, eq)
• Fossa clitoridis (eq, ca)
• Corpus spongiosum glandis (eq, ca)
• Corpus cavernosum clitoridis
  
  • Ca: most of the erectile tissue is replaced by fat
  • Fe: contains a cartilga corresponding to os penis
  • Un: mostly fibrous

Question 3

Vagina

Location

Answer 3

• Located in a median position within the pelvic cavity
• Dorsal: rectum
• Ventral: bladder
• Mostly retroperitoneal, but the cranial parts are covered by peritoneum
• From cervix uteri to vestibulum vaginae (or hymen)
  
  • Extends from ostium uteri externum to ostium urethrae externum

Question 4

Vagina

What is the junction between the vagina and vestibulum vagina called?

Answer 4

Ostium vaginae

At the leves of the ostium urethrae externum

Question 5

Vagina

Which structures can be found in the vagina?

Answer 5

• Fornix vaginae
  
  • Cranial blind pouch of the vagina
  • Surrounding the portio vaginalis cervicis
• Hymen
  
  • ​Transverse fold
  • Cranial to ostium urethrae externum
  • Most prominant in horse and pig
• Ostium vaginae
  
  • ​Opening of the vagina into the vestibulum vaginae
  • It is marked by the hymen

Question 6

Vagina

Draw the vagina

Answer 6

Question 7

Vestibulum vaginae

Location

Answer 7

• Lies behind arcus ischiadicus
• Extends from ostium urethrae externum to the vulva
• Combines reproductive and urinary functions

Question 8

Vestibulum vaginae

Which structures can be foun in the vestibulum vaginae?

Answer 8

• Bulbus vestibuli (eq, ca)
  
  • Cavernous tissue in the lateral wall of the vestibule
• Diverticulum suburethrale (su, ru)
  
  • Ventral evagination
  • Opens together with urethra into the vagina (can complicate catherisation of the urinary bladder)
• Tuberculum urethrale (ca)
  
  • An elevation bearing ostium urethrae externum

Question 9

Vestibulum

Wall

Answer 9

• The wall of the vestibule containt vesibular glands​
  
  • Keeps the muscosa of the vesibule moist and facilitates parurition
• Minor vestibular glands (all species)
  
  • Small, but numerous
  • In the ventral and lateral wall
• Large glandular mass (ru, fe)
  
  • Drains by 1 duct, present on each side of the vestibule
  • Ducts open on the lateral wall of the vestiuble

Question 10

Vulva

Which structures can be found on the vulva?

Answer 10

• Labium vulvae
  
  • ​2 labia that meet at dorsal and ventral commissures
  • Surrounding the vertical vulvar opening
  • Dorsal commissure: rounded
  • Ventral commissure: pointed
  • Eq: oppossite (dorsal: pointed, ventral: rounded)
• Rima vulvae
  
  • ​Pudendal fissure between right and left labia
  • External urogenital opening

Question 11

Clitoris

Which structures can be found in the clitoris?

Answer 11

• The clitoris is analogous with the penis
• Can be divided into 2 parts:
  
  • Corpus clitoridis
  • Glans clitoridis
    
    • Eq: Sinus clitoridis invade the glans clitoridis
• Crus clitoridis
  
  • ​Right and left crura are attached to arcus ischiadicus
  • Join corpus clitoridis
• Corpus clitoridis
  
  • ​Composed of fused corpora cavernosa
• Glans clitoridis
  
  • ​Best developed in ca and eq
  • Sinus clitoridis (eq)
  • Frenulum clitoridis (ca, eq)
    
    • Median dorsal attachment of glans to vestibular wall of preputium
• Preputium clitoridis
  
  • ​Prepuce of the clitoris
• Fossa clitoridis (eq, ca)
  
  • Preputial cavity
  • The clitoris lies within fossa clitoridis
  • Equivalent to the prepuce of the males
  • Covered by mucosal folds
• Corpus cavernosum clitoridis
  
  • ​Right and left corpus cavernosum are fused to form corpus clitoridis
  • Ca: most of the erectile tissue is replaced by fat
  • Fe: contains a cartilga corresponding to os penis
  • Un: mostly fibrous
• Corpus spongiosum glandis (ca, eq)
  
  • Continous with pars intermedia bulborum

Question 12

Urethra feminia

Answer 12

• Extends caudally on the pelvic floor, ventral to the reproductive tract
• Begins at the cervix vesicae
• Passes through the wall of the vagina and opens with the ostium urethrae externum
  
  • ​Between the junction . between vagina and vestibulum vaginae
• Ru, su: urethralis muscles encloses diverticulum suburethrale, which opens together with the urethra into the vagina
• Muscular coat of the urethra is continues with that of the urinary bladder
  
  • ​Outer longitudinal layer of smooth muscles
  • Inner circular layer of smooth muscles

Structures:

• Ostium urethrae externum​
• Crista urethralis
  
  • ​Dorsal longitudinal mucosal ridge extending from the junction of the plica uretericae caudally to the middle of the urethra

Question 13

Blood supply

Answer 13

• A. iliaca interna
  
  • A. pudenda interna
    
    • A. perinealis ventralis
      
      • R. labialis dorsi
    • _​_A. clitoridis
      
      • ​A. profunda clitoridis
      • A. dorsalis clitoridis
      • A. bulbi vestibuli
    • A. vaginalis
• A. iliaca externa (riktig branching?, kommer a. profunda femoris etter eller er det feil?)
  
  • Tr. pudendoepigastricus
    
    • A. pudenda externa
      
      • A. labialis ventralis

Question 14

Innervation

Answer 14

• Autonomic and volunatry
• Parasympathetic:
  
  • ​Sacral outflow and reches genital tract via pelvic nerves
• Sympathetic:
  
  • ​Ggl. mesentericuc caudale and plexus
    
    • ​Hypogastric nerves
    • Pelvic plexus
• Plexus uterovaginalis
• Nn. vaginalis
• Motor & sensory innervation:
  
  • Sacral plexus
    
    • ​​N. pudenda
      
      • N. rectalis caudalis