Lecture 20: Perineum Flashcards
Where is the perineum?
Below pelvic floor
What does the urogenital triangle contain?
Openings of urinary and reproductive systems
What does the anal triangle contain?
Anus and external sphincter
How do the vagina, urethra and rectum exit the body?
On an angle, form functional sphincters (anal canal angulated in posterior direction)
What is the cloaca?
Common ejection chamber in development for urogenital system and GIT
What germ layer is the cloaca?
Endoderm
What is the perineal membrane and where is it?
Strong supporting membrane, fills urogenital triangle
Where is the deep perineal pouch?
Below pelvic diaphragm and above perineal membrane
What is present in the deep perineal pouch?
Urethra and vagina (females), transverse perineal muscels
What are the features of the external urethral sphincter?
Skeletal muscle, slow twitch
What are the additional sphincteric components in females?
Urethrovaginalis, compressor urethrae - need to maintain nerve supply to these to maintain continence
What is the superficial perineal pouch?
Outlet for urethra, vagina and anus
What is the function of bulbospongiosus?
Additional support for urethra, skeletal muscle, contracts to expel last bit or urine, attached to perineal body
Where is erectile tissue present?
Corpora cavernosa and corpus spongiosum, external genitalia, clitoris
What happens if the bulb is damaged at the level of the apex of prostate?
Extravasation of urine into the extraperitoneal cavity
What happens if the bulb is damaged at the penis?
Extravasation of urine into superficial perineal space
What makes up the external genitalia of the female
Vulva, labia majora, labia minora, glans
What are the features of the ischio (rectal) anal fossa?
Contains fat and inferior rectal nerve - allows distension of rectum and anus during defeacation - prone to abscess formation
What is the internal anal sphincter?
Smooth muscle wall thickening of anal canal - under reflex control
Where does the inferior rectal nerve branch from?
S4 - pudendal nerve