L21 - The Perineum Flashcards
The perineum
- lies inferior to the pelvic floor, between the lower limbs
- formed from soft tissue inferior to the pelvic floor, ending wiht skin
Superficial
inferior, closer to the skin
deep
superior, closer to the pelvic diaphragm
pelvic floor review muscles
- obturator internus
- levator ani
- coccygeus
- urogenital hiatus
- rectal hiatus
- piriformis
borders of the perineum
- pubic symphysis
- ishciopubis ramus
- ischial tuberosity
- coccyx/sacrum
triangles of the perineum
- urogenital triangle
- anal triangle
urogenital triangle
- anterior portion of perineum
- bounded by 1) pubic symphysis, 2) ishcial tubersoity
anal triangle
- posterior portion of perineum
- bounded by 1) ischial tuberosities 2) coccyx
Male genitalia (3)
- penis
- scrotum
- urethra
body of penis structures (3)
- glans
- corpus cavernosum
- corpus spongiosum
root of penis strctures (2)
- crus
- bulb
penis structures (transverse section through penile shaft) - (4)
- corpus cavernosum
- corpus spongiosum
- deep penile artery
- urethra
Urethra structurs (7)
- bladder
- prostate
- prostatic urethra
- membranpous urethra
- spongy urethra
- corupus spongiosum
- external urethral orifice
Female genitalia structures
- prepuce of clitoris
- mons pubis
- clitoris
- labia majora
- labia minora
pudendal cleft
- space between labia majora and labia minora
Female genitalia - vestibule borders
- clitoris: anterior border
- labia minora: lateral border
- fourchette: posterior border
Female genitalia - vestibule components
- external urethral orifice
- vaginal orifice
- bulb of vestibule
- greater vestibular glands
Erectile tissue - root: structures
- crus of clitoris
- greater vestibular gland
- bulb of vestibule
Erectile tissue - body: structures
- glands of clitoris
- body of clitoris (corpora cavernosa)
urethra: structures
- external urethral sphincter (surrounds entire urethra)
- urethrovagunal sphincter (surrounds urethra and vagina)
- compressor urethrae (surrounds anterior urethra)
urogenital triangle
- anterio rportion of perineum
- bounded by 1) pubiv symphysis 2) ischia tuberosities
urogenital triangle components superficial to deep
- skin
- perineal fascia
- superificial perineal pouch
- perineal membrane
- deep perineal pouch
- pelvic floor
deep perineal pouch
- between pelvic floor superiorly, and perineal membrane inferiorly
- lies superior the perineal membrane
- forms the external urethral sphincter
deep perineal pouch: males
- deep transverse perineal muscle
- external urethral sphincter (voluntary control, surrounds membranous urethra)
deep perineal pouch: females
- external urethral sphincter
- urethrovaginal sphincter
- compressor urethrae
- deep transverse perineal muscle
perineal membrane
deep perineal pouch –> perineal membrane –> superificial perineal pouch
superificial perineal pouch
- between perineal membrane superiorly, and deep perineal fascia inferiorly
- lies inferior to the perineal membrane
- superior limit –> perineal membrane
- inferior limit –> colles’ fascia
superificial perineal pouch: males
- bulbospongiosus (compresses bulb of penis during erection)
- ischiocavenrbous (compresses crus of penis during erection)
- superiorical transvers perineal muscle
superificial perineal pouch: females
- bulbospongiosus (compresses bulb of clitoris during erection)
- ischiocavenrbous (compresses crus of clioris during orgasm)
- superiorical transvers perineal muscle
perineal fascia: superifical layer
continous with Camper’s fascia pf anterior abdominal wall
perineal fascia: deep layer
- continuous with Scarpa’s fascia of the anterior abdominal wall
- Colles’ fascia
Perineal body
convergence/interlacing of
- bulbospongious
- superifical/deep perineal muscles
- external anal sphrincter
- pelvic floor muscles
Anal triangle contents
- anal aperture
- external anal sphincter
- ischiorectal fossa
- pudendal canal
Anal triangle
- posterior portion of perineum
- bounded by 1) ischial tuberosities 2) coccyx
- no perineal membrane here!!
Ischiorectal fossa
- obturator internus
- levator ani
Borders of the ischiorectal fossa
- lateral border: obturator internus
- superior border: levator ani
- medial border: external anal sphincter
- inferior border: perineal fascia
pudendal canal: neurovasculature structures
- pudendal nerve
- internal pudenda; artery
- internal pudendal vein
anal canal structures
- external anal sphincter
- internal anal sphincter
- rectal ampulla
- anal canal
internal anal sphincter
involuntary: relaxes during normal defecation
External anal canal sphincter functions
voluntary: compresses to keep spincter shut
Blood supply
- abdominal aorta (bifurcation at L4)
- external iliac artery (blood supply to the lower limbs)
- common iliac artery (bifurcation at sarcoiliac joint)
- internal iliac artery (blood supply to the pelvis
blood supply - perineum
- internal iliac artery
- internal pudendal artery
blood supply - rectum
- inferior mesenteric artery
- superior rectal artery
- internal iliac artery
- middle rectal artery
- inferior rectal artery
