Perineum Flashcards
What is the perineum?
- Area where external genitalia and anus are found
- Roughly diamond shaped area
- Below pelvic diaphragm
What can the perineum be divided into?
- Anteriorly: Urogenital triangle
- Posteriorly: Anal triangle
What are the 2 superficial fascial layers of the perineum?
- Superficial fatty layer (continuous with Camper’s)
- Deep membranous layer (Colle’s or perineal)
Continuous with Scarpa’s fascia of the abdomen
What does the fatty layer fuse with in males?
- Fuses with the membranous layer of superficial fascia in the penis and scrotum to become dartos fascia (and muscle)
- Continous posteriorly with the ischio-anal fat pad in the anal region
What is the membranous layer continous with in males?
- Dartos fascia in penis and scrotum
- Attached posteriorly to the posterior margin of the perineal membrane and perineal body
- Fuses with fascia lata
What is dartos fascia and muscle combined with to become?
Superfial and deep layers in penis and scrotum
What does the fatty layer of the subcutaneous tissue of the perineum become in females?
- Makes up the substance of the labia majora
- Continous posteriorly with the ischio-anal fat pad in the anal region
What does the membranous layer attached to and fuse with in females?
- Attached posteriorly to the posterior margin of the perineal membrane and perineal body
- Fused with fascia lata
What is the perineal membrane?
- Layer of fibrous tissue in the perineum
- Spans the urogenital triangle between the ischiopubic rami
- Attaches to the perineal body in the midline posteriorly
- Provides major support for urogenital organs
How do nerves and vessels reach the penis/clitoris?
Anterior aperture in perineal membrane
What does the deep perineal membrane divide?
Divides urogenital triangle into 2 potential spaces:
- Deep perineal (siperior)
- Superficial perineal (inferior) compartment (pouch)
What do the cocygeus and levator ani muscle make up?
The pelvic diaphragm
What does the deep fascia of the abdominal wall become at the pelvis?
Pelvic fascia
What fascia covers the levator ani and cocygeus muscle?
- Superior fascia of pelvic diaphragm
- Inferior fascia of plevic diaphragm
What lies inbetween the Inferior fascia of pelvic diaphragm and perineal membrane?
Deep perineal pouch
- Deep transverse perineal muscle (v. small)
- External urethral sphincter
- Bulbourethral gland
What muscles lie between the pernial fascia and perineal membrane?
Superficial perineal pouch
- Ischiocavernous muscle
- Bulbospongiosus
- Superficial transverse pernieal muscle
Name the layers of fascia in the perineum from superficial/inferior to deep/superior?
- Perineal fascia
- Perineal membrane
- Inferior fascia of pelvic diaphragm
- Superficial fascia of pelvic diaphragm
What is the perineal body?
Tendinous structure in the midline between the vagina and anus where two sides of perineal diaphragm muscles fuse
Where is the superficial perineal pouch?
Potential space between the perineal fascia and the perineal membrane, bounded laterally by the ischiopubic rami
What does the superficial perineal pouch contain in males?
- Root (bulb and crura) of the penis and associated muscles (ischiocavernosus and bulbospongiosus)
- Proximal (bulbous) part of the spongy urethra
- Superficial transverse perineal muscles
- Deep perineal branches of the internal pudendal vessels and pudendal nerves
What is the function of the ischiocavernosus in men?
- Covers the crus of penis
- Maintains erection of penis
What is the function of the bulbospongiosus in men?
- Encloses bulb of penis
- Compresses bulb of penis to expel last drops of urine/semen
- Assists erection
What does the superficial perineal pouch contain in females?
- Crus of the clitoris and ischiocavernosus muscle
- Bulb of vestibule and bulbospongiosus muscle
- Greater vestibular glands
- Superficial transverse perinela muscles
- Deep perineeal branches of the internal pudendal vessels and pudendal nerves
What is the function of the ischiocavernosus in females?
- Covers the crus of clitoris
- Maintains erection of clitoris
Whaat is the function of the bulbospongiosus in females?
- Encloses bulb and greater vestibular gland
- Sphincter of vagina
- Assists in erection of clitoris
- Compresses greater vestibular gland
Where is the deep perineal pouch located?
Potential space between the perineal membrane, the inferior fascia of the pelvic diaphragm, and the inferior portion of the obturator fascia
What the deep perineal pouch include in males?
- Membranous urethra
- External urethral sphincter
- Bulbo-urethral glands
- Deep transverse perineal muscles
- Dorsal neurovascular structures of the penis
- Anterior recess of the ischio-anal fossa
What is included in the deep perineal pouch in females?
- Proximal part of the urethra
- Inferior part of the external urethral sphincter muscle
- Compressor urethra
- Urethrovaginal sphincter
- Deep transverse perineal muscles
- Dorsal neurovascular structures of the clitoris
- Anterior recess of the ischio-anal fossa
What is the ischioanal fossa?
- Large fascia-lined, wedge-shaped spaces between:
- Skin of the anal region
- Levator ani (pelvic diaphragm)
- Obturator internus and ischium
- Anal canal
How can the ischional fossa communicate with each other?
Posterior to the anal canal
What does the ischioanal fossa contain?
- FAtty tissue that allows for changes in the position and size off the anal canal and anus during defecation
- The inferior rectal vessels and nerves that suppy the external anal sphincter
- The perforating branches of S2 and S3
- Perineal branch of the S4 nerve
- Pudendal neve and internal pudendal vessels (lateral wall)
What is patholigically significant about the ischioanal fossa?
Site of infection and abscess that may require surgical intervention (can pass through fibres of anal sphinter into fossa which then conects to deep perineal pouch)
What is the pudendal canal also known as?
Alcock’s canal
What is the pudendal canal?
A horizontal passageway within the obturator fascia, along the lateral wall of the ischio-anal fossa
What does the pudendal canal contain?
- Pudendal nerve
- Internal pudendal artery
- Internal pudendal vein
- Branches will pierce wall of canal and travel in perineum towards either anal canal or perineal branches
What do the internal pudendal vessels supply?
- Perineum
- \Urethra
- Posterior 2/3 of scrotum or labia
- Cavernous tissue of the penis or clitoris
- Skin of shaft and glans of the penis or clitoris
What do the external pudendal vessels supply?
Anterior 1/3 of scrotum or labia
What is the external pudendal a branch of?
Femoral vessels
What does the lymph from superficial perineal structures (e.g penis, scrotum and labia) drain to?
Superficial inguinal lymph nodes
What does the lymph from the deep perineal structures (eg corpora cavernosa, corpus spongiosum, bulb of penis and vestibule proximal vagina and urethra) drain to?
Internal iliac nodes
What is the nerve supply to the perineum derived from?
S2-4 pudendal nerves and pelvic plexuses (aka inferior hypogastric)
Where can urine travel if membranous urethra is ruptured?
- Will escape into deep perineal pouch
- May pass through urogenital hiatus and distribute extraperitoneally around bladder
What happens to urine if the proximal spongy (bulbar) urethra is ruptured
- Escapes through the rupture into the superficial perineal pouch
- Descends into the scrotum
- RIses onto the anterior abdominal wall deep to the superficial fascia
- “Blue swimming trunks” - bruising trapped under Scarpa’s anf Colles (perineal) fascia only in the front
