Perineum Flashcards
Perineum
Shallow compartment bounded by pelvic outlet 1. Pelvic diaphragm fascia separates it from pelvic cavity 2. Surface diamond-shaped A. Mons pubis - anterior B. Medial thighs - lateral C. Gluteal folds - posterior 3. Bony boundaries A. Pubic symphysis B. Ischiopubic rami C. Ischial tuberosities D. Sacrotuberous lig E. Sacrum F. Coccyx 4. Anal canal 5. Urogenital triangle 6. Perineal body
Anal triangle
- Anal canal
- Anus
- Surrounded by ischio-anal fat
Urogenital triangle
- Closed by perineal membrane between ischiopubic rami
- Urethra
- Vagina
- Membrane provide attachment for erectile bodies
Perineal body
Central tendon of perineum
1. Irregular mass of collagenous and elastic muscles
2. Skeletal and smooth muscles posterior vaginal vestibule/bulb of penis and anterior angus
3. Muscle convergence
A. Bulbospongiosus
B. External anal sphincter
C. Superficial and deep transverse perineal
D. External urethral sphincter
E. Levator ani
F. Muscular coats of rectum
4. Blends w/ posterior border of perineal membrane anteriorly and rectovesical or rectovaginal septum superiorly
Perineal fascia
- Superficial fatty layer of subcutaneous
- Deep membranous layer of subcutaneous
- Deep perineal fascia (investing or Gallaudet)
Superficial fatty layer of subcutaneous peritoneal fascia
- Both sexes continuous posteriorly w/ ischio-anal fat pad
- Females: continuous to labia majora and mons pubis
A. Continuous w/ Camper’s fascia in abdominal cavity - Males: diminished in urogenital triangle
A. Replaced by Darto’s in penis and scrotum
Deep membranous layer of subcutaneous peritoneal fascia
- Doesn’t extend into anal triangle
- Attaches posterior margin perineal membrane and perineal body posteriorly and fascia lata laterally
- Females: continuous w/ abdominal deep membranous fascia
- Males: colles fascia couninuous w/ Dartos in scrotum and penis and scarpa’s in abdomen
Deep perineal fascia
Investing or Gallaudet 1. Invests A. Ischiocavernosus B. Bulbospongiosus C. Superficial transverse perineal 2. Attaches A. Ischiopubic rami laterally B. Suspensatory lig of penis/clitoris anteriorly 3. Continuous w/ deep fascia in abdomen
Superficial perineal pouch
- Potential space between perineal fascia and membrane
- Males
A. Root of penis
B. Ischiocavernosus m.
C. Bulbospongiosus m.
D. Bulbous part spongy urethra
E. Superficial transverse perineal m.
F. Deep perineal branch of internal pudendal vessels and nerves - Female
A. Clitoris
B. Ischiocavernosus m.
C. Bulbs of vestibule
D. Bulbospongiosus m.
E. Greater vestibular glands
F. Superficial transverse perineal m.
G. Deep perineal branch of internal pudendal vessels and nerves
Deep perineal pouch
1. Boundaries A. Perineal membrane - inf B. Inf fascia pelvic diaphragm - sup C. Obturator fascia - lat 2. Both sexes A. Part of urethra B. Inf part external erethral sphincter m. C. Ant extension of ischio-anal fat pads 3. Males A. Intermediate urethra B. Deep transverse perineal m. C. Bulbourethral glands D. Dorsal neurovascular structures of penis 4. Females A. Prox urethra B. Mass of smooth muscle C. Dorsal neuorvasculature of clitoris
Anal triangle
- Ischio-anal (ischiorectal) fossae
- Pudendal canal (Alcock canal) and neurovascular bundle
- Anal canal
Ischio-anal (ischiorectal) fossae
Part of anal triangle
- Fascia-lined, wedge-shaped spaces on sides of anal canal between skin and pelvic diaphragm
- 2 communicate by posterior natal space over anococcygeal lig
- Fat-filled: support anal canal but allow movement
Pudendal canal (Alcock canal)
Part of anal triangle
1. Horizontal passageway w/in obturator fascia
2. Enter at lesser sciatic notch
A. Internal pudendal a. And v.
B. Pudendal n.
C. N. To obturator internus
3. Internal pudendal vessels and pudendal n. Serve most of perineum
A. Micturation
B. Defecation
C. Erection
D. Ejaculation
E. Parturition
4. Internal pudendal a. And n. -> inf rectal a. And n.
A. Passes medially -> external sphincter and peri-anal skin
B. Inf. Rectum
Pudendal n.
S2-S4
1. Major n. Of perineum
2. Exits sacral foramina, under greater sciatic foramen
3. Enters perineum via lesser sciatic foramen
4. Branches
A. Inferior rectal n. - external sphincter and anal canal inf pectinate line
1. Communicates w/ perineal br. Of post cutaneous n. In thigh
B. Perineal n.
C. Dorsal n. Of penis/clitoris
Perineal n.
- Superficial n. -> post scrotal/labial (cutaneous) br.
2. Deep n. -> muscles of deep and superficial perineal pouches, skin of vestibule, mucosa innermost vagina