20-03-23 - Perineum and Urogenital triangle Flashcards
Learning outcomes
- Define the perineum and the urogenital and anal triangles
- Define the perineal fascia, perineal membrane
- Define the deep and superficial perineal pouches and describe their boundaries and contents
- Define the ischio-anal fossae and describe their boundaries and contents
- Define the pudendal canal and describe their boundaries and contents
- Discuss the clinical implications of the structures within the perineum
Where is the perineum located?
What shape is it?
What is it divided into?
- The perineum is located below the pelvic diaphragm
- It is diamond shaped
- It is divided into a urogenital triangle anteriorly and an anal triangle posteriorly
What are the 3 layers of the abdomen?
How does this structure differ in the perineum?
- 3 layers of the abdomen:
1) Skin (cutis)
2) Subcutaneous tissue (Superficial fascia, SF)
* Subcutaneous/superficial fatty layer (Camper’s fascia)
* Deep membranous layer (Scarpa’s fascia)
3) Abdominal muscles with their investing fasciae
- This structure in the perineum will be maintained with some differences
Where does the abdominal fascia continue to?
What are the 2 layers of superficial fascia (subcutaneous tissue) of the perineum?
- 2 layers of superficial fascia (subcutaneous tissue) of the perineum:
1) Superficial fatty layer
* Continuous with Camper’s fascia of the abdomen
2) Deep membranous layer (Colles’ or perineal fascia)
* Continuous with Scarpa’s fascia of the abdomen
What are the 2 fascial layers of the fascia of the perineum in males?
What is each layer continuous with?
What does each layer fused with?
Where is the membranous layer attached?
- 2 fascial layers of the fascia of the perineum in males:
1) Fatty layer
* Continues posteriorly with the ischio-anal fat pad in the anal region
* Fuses with the membranous layer of superficial fascia in the penis and scrotum to become dartos fascia (and muscle)
2) Membranous layer
* Continuous with the dartos fascia (doesn’t have fat) in the penis and scrotum
* Fuses with fascia lata (deep fascia of the thigh)
* Attached posteriorly to the posterior free margin of the perineal membrane and perineal body
What are the 2 fascial layers of the fascia of the perineum in females?
What structure makes up the labia majora?
What is the fatty layer continuous with?
Where is the membranous layer attached?
What is the membranous layer fused with?
- 2 fascial layers of the fascia of the perineum in females:
1) Fatty layer of subcutaneous tissue of the perineum
* Makes up the substance of the labia majora
* Continues posteriorly with the ischio-anal fat pad in the anal region
2) Membranous layer of the perineum
* Attached posteriorly to the posterior margin of the perineal membrane and perineal body
* Fused with fascia lata (deep fascia of the thigh)
What is the perineal membrane?
What structure does it span?
What is the perineal membrane attached to?
What is its purpose?
What is the anterior aperture of the perineal membrane for?
- The perineal membrane is a layer of fibrous tissue in the perineum
- It spans the urogenital triangle between the ischiopubic rami
- The perineal membrane attaches to the perineal body in the midline posteriorly
- It provides major support for the urogenital organs
- There is an anterior aperture on the perineal membrane for the passage of nerves and vessels to the penis or clitoris
How is the urogenital triangle divided up?
- The urogenital triangle is divided by the perineal membrane into deep perineal and superficial perineal pouches
Perineal pocuhes summary diagram
Perineal pouches summary diagram
What is the superficial perineal pouch?
What structures is it between?
What structure is it bounded by?
- The superficial perineal pouch is a potential space
- It is between the perineal fascia and the perineal membrane, and is bounded laterally by the ischiopubic rami
What 6 structures does the superficial perineal pouch contain?
Where is the Ischiocavernosus muscle located?
What is its role?
Where is the Bulbospongiosus muscle located?
What are 4 roles of the Bulbospongiosus muscle?
What is the role of the Superficial transverse perineal muscle?
- 6 structures the superficial perineal pouch contains:
1) Crus of the penis / clitoris and ischiocavernosus muscle
* The Ischiocavernosus muscle covers the crus of penis/clitoris
* It maintains erection of penis
2) Bulb of penis / vestibule and bulbospongiosus muscle
* The bulbospongiosus muscle encloses bulb of penis / vestibule and greater vestibular gland
* 4 roles of the Bulbospongiosus muscle:
1) Assists erection of penis / clitoris
2) Compresses bulb of penis to expel last drops of urine/semen in males
3) Compresses greater vestibular gland in females
4) “sphincter” of vagina
3) Proximal (bulbous) part of the spongy urethra in males
4) Greater vestibular gland in females
5) Superficial transverse perineal muscles
* Stabilizes the perineal body
6) Deep perineal branches of the internal pudendal vessels and pudendal nerves
Where is the deep perineal pouch located?
What 6 structures are located in the deep perineal pouch in males?
- The deep perineal pouch is a Potential space between the perineal membrane, the inferior fascia of the pelvic diaphragm, and the inferior portion of the obturator fascia
- 6 structures located in the deep perineal pouch in males:
1) Membranous urethra
2) External urethral sphincter
3) Bulbo-urethral glands
4) Deep transverse perineal muscles
5) Dorsal neurovascular structures of the penis
6) Anterior recess of ischio-anal fossa
What are the 7 structures located in the deep perineal pouch in females?
- 7 structures located in the deep perineal pouch in females:
1) Proximal part of the urethra
2) Inferior part of the external urethral sphincter
3) Compressor urethra
4) Urethrovaginal sphincter
5) Deep transverse perineal muscles
6) Dorsal neurovascular structures of the clitoris
7) Anterior recess of ischioanal fossa
What is the ischioanal fossa?
What 4 structures is the ischioanal fossa located between?
- The ischioanal fossa is a large fascia-lined, wedge-shaped space
- 4 structures the ischioanal fossa is located between:
1) Skin of the anal region
2) Levator ani (pelvic diaphragm)
3) Obturator internus and ischium
4) Anal canal
How can the ischioanal fossa each side communicate with each other?
What 5 structures does the ischioanal fossa contain?
What can the ischioanal fossa be the site of?
- The ischioanal fossa each side may communicate with each other posterior to the anal canal
- 5 structures the ischioanal fossa contains:
1) Fatty tissue that allows for changes in the position and size of the anal canal and anus during defecation
2) Inferior rectal vessels and nerves that supply the external anal sphincter
3) Perforating branches of S2 and S3
4) Perineal branch of the S4 nerve
5) Pudendal nerve and internal pudendal vessels*
- The ischoanal fossa can be the site of infection and abscess that may require surgical intervention
What is the Pudendal canal (Alcock’s canal)?
Where is it located?
What 2 structures does the pudendal canal contain?
What do these structures run in?
- The Pudendal canal (Alcock’s canal) is a horizontal passageway within the obturator fascia, along the lateral wall of the ischio-anal fossa
- 2 structures the pudendal canal contains:
1) Pudendal nerve
2) Internal pudendal vessels - The structures run in a fascial sheathe
What 5 structures do the internal pudendal vessels supply?
What do the external pudendal branch of femoral vessels supply?
- 5 structures the internal pudendal vessels supply:
1) Perineum
2) Urethra
3) Posterior 2/3 of scrotum or labia
4) Cavernous tissue of penis or clitoris
5) Skin of shaft & glans of penis or clitoris - The external pudendal branch of femoral vessels supply the anterior 1/3 of scrotum or labia
What are 3 examples of superficial perineal structures?
What lymph nodes do the superficial perineal structures drain into?
- 3 examples of superficial perineal structures:
1) Penis
2) Scrotum
3) Labia - Superficial perineal structures (such as the penis, scrotum & labia) drain into the superficial inguinal lymph nodes
What are 4 examples of deep perineal structures?
What lymph nodes do the deep perineal structures drain into?
- 4 examples of deep perineal structures:
1) Corpora cavernosa
2) Corpus spongiosum
3) Bulb of penis & vestibule
4) Proximal vagina & urethra - Deep structures (such as the corpora cavernosa, corpus spongiosum, bulb of penis & vestibule, proximal vagina & urethra) drain into the internal iliac lymph nodes
What 3 places can urine go if the proximal spongy (bulbar) urethra is ruptured?
What appearance can this give?
- 3 places urine can go if the proximal spongy (bulbar) urethra is ruptured:
1) Escapes through the rupture into the superficial perineal pouch
2) Descends into the scrotum
3) Rises onto the anterior abdominal wall deep to the superficial fascia.
- If the proximal spongy (bulbar) urethra is ruptured, this can give the appearance of blue swimming trunks bruising, where the bruising doesn’t extend posterior to the perineal body
What 2 places can urine go if the membranous urethra is ruptured?
- 2 places can urine go if the membranous urethra is ruptured:
1) Will escape into deep perineal pouch
2) May pass through urogenital hiatus and distribute extraperitoneally around bladder
Deep perineal pouch summary diagram
Superficial perineal pouch summary diagram
