Perineum Flashcards
Describe the location of the perineum
Between:
- inferior surface of pelvic diaphragm superiorly
- skin inferiorly
Describe the divisions of the perineum, and the landmarks that define it
- urogenital triangle anteriorly
- anal triangle posteriorly
- marked by pubic symphysis most anteriorly and coccyx most posteriorly and divided by line between right and left ischial tuberosities
Describe the fascia of the perineum
- continuous with that of abdo fascia
- superficial fatty layer is continuous with Camper’s fascia
- deep membranous layer (Colle’s fascia) is continuous with Scarpa’s fascia
Describe how the fascia of the perineum changes in males
- fatty layer fuses with membranous layer of superficial fascia of penis and scrotum to become dartos fascia and muscle
- continuous posteriorly with ischio-anal fat pad in anal region
- membranous layer continuous with dartos fascia and attached to posterior margin of perineal membrane and body
- fuses with fascia lata
Describe how the fascia of the perineum changes in females
- fatty layer of subcutaneous tissue makes up labia majora and is continuous posteriorly with ischio-anal fat pad in anal region
- membranous layer attached to posterior margin of perineal membrane and body
- fused with fascia lata
Describe the location of the perineal membrane
- spans urogenital triangle between ischiopubic rami
- attaches to perineal body in midline posteriorly
What are the main features of the perineal membrnae?
- major support for urogenital organs
- has anterior aperture for passage of nerves and vessels to penis or clitoris
Describe the division of the urogenital triangle
- divided by perineal membrane
- deep perineal (superior) pouch
- superficial perineal (inferior) pouch
What are the boundaries of the perineal pouches?
Superficial:
- roof: perineal membrane
- floor: perineal fascia
Deep:
- roof: inferior fascia of pelvic diaphragm
- floor: perineal membrane and muscles
What is the contents of the deep perineal pouch in males?
- membranous urethra
- external urethral sphincter
- bulbo-urethral glandes
- deep transverse perineal muscles
- dorsal neurovascular structures of penis
- anterior recess of ischio-anal fossa
What is the contents of the deep perineal pouch in females?
- proximal part of urethra
- inferior part of external urethral sphincter
- compressor urethra
- urethrovaginal sphincter
- deep transverse perineal muscles
- dorsal neurovascular structures of clitoris
- anterior recess of ischio-anal fossa
What is the contents of the superficial perineal pouch in males?
- root of the penis (bulb and crura) and associated muscles (ischiocavernosus and bulbospongiosus)
- proximal part of spongy urethra
- superficial transverse perineal muscles
- deep perineal branches of internal pudendal vessels pudendal nerves
What is the contents of the superficial perineal pouch in females?
- crus of clitoris and ischiocavernosus muscle
- bulbs of vestibule and bulbospongiosus muscle
- greater vestibular glands
- superficial transverse perineal muscles
- deep perineal branches of internal pudendal vessels and pudendal nerves
What is the functions of the ischiocavernosus and bulbospongiosus muscles in females?
Ischiocavernosus:
- covers crus of clitoris
- maintains erection of clitoris
Bulbospongiosus:
- encloses bulb and greater vestibular gland
- sphincter of vagina
- assists in erection of clitoris
- compresses greater vestibular gland
Describe the location of the ischioanal fossa
Between:
- skin of anal region
- levator ani
- obturator internus and ischium
- anal canal
What is the contents of the ischioanal fossa?
- fatty tissue that allows changes in position and size of anal canal and anus during defecation
- inferior rectal vessels and nerves that supply external anal sphincter
- perforating branches of S2 and 3
- perineal branch of SA4
- pudendal nerve and internal pudendal vessels
Describe the position and contents of the pudendal canal
- horizontal and within obturator fascia, along lateral wall of ischio-anal fossa
Contains:
- pudendal nerve
- internal pudendal artery
- internal pudendal vein
Describe the lymphatic drainage of the perineum
- superficial structures (eg. penis, scrotum, labia) to superficial inguinal lymph nodes
- deep structures (eg. c. cavernosa, c. spongiosum, bulb of penis, proximal vagina and urethra) to internal iliac nodes
Describe the nerve supply of the perineum
somatic motor, sensation and autonomic is derived from S2-4 pudendal nerves and pelvic plexuses
Describe the clinical significance of rupture of the urethra
If Membranous:
- urine will escape into deep perineal pouch
- may pass through UG hiatus and go extraperitoneally around bladder
If Spongy:
- urine will escape through rupture into superficial perineal pouch
- descend into scrotum and rise onto anterior abdo wall deep to superficial fascia
- presents as bruising trapped under Scarpa’s and Colle’s fascia
