Perineum Flashcards
What is the perineum?
the part of the trunk below the pelvic diaphragm
What is the shape of the perineum?
a diamond-shaped space which has the same boundaries as the pelvic outlet
What divides the perineum into two triangles?
a transverse line connecting the two ischial tuberosities
What are the triangles of the perineum?
- urogenital triangle (anterior)
- anal triangle (posterior)
What is the position of the triangles in anatomical position?
the urogenital triangle lies in the horizontal plane while the anal triangle is tilted upward
What are the boundaries of the urogenital triangle?
- anterior: pubic symphysis
- anterolateral: ishiopubic rami
- posterior: transverse line through ischial tuberosities
What are the layers of the urogenital triangle?
- skin
- superficial perineal pouch
- superficial perineal fascia
- deep perineal fascia
- contents - perineal membrane
- deep perineal pouch
- inferior fascia of the pelvic diaphragm
What is the superficial perineal fascia?
- includes fatty layer (superficial) and membranous layer (deep)
- membranous layer is also known as Colle’s Fascia
What is Colle’s fascia continuous with?
- dartos muscle of the scrotum
- Scarpa’s fascia
Describe the deep fascia.
- it intimately invests the muscles of the superficial perineal pouch
- is fused anteriorly with the suspensory ligament of the penis/clitoris
Where is the superficial perineal pouch?
lies between the superficial perineal fascia and the perineal membrane
What does the superficial perineal pouch contain?
- perineal body
- superficial transverse perineal membrane
- ischiocavernosus muscle
- crura of the penis/clitoris
- blubospongiosus muscle
- bulb of the penis/vestibule
- greater vestibular gland (females)
- branches of the internal pudendal artery
- branches of the pudendal nerve
What kind of tissue are the crus and bulb composed of?
cavernous erectile tissue
What is the perineal body?
- a fibromuscular mass which is located in the center of the perineum between the anal canal and bulb of the penis/vagina
- it is an important point of muscle attachment
Which muscles attach to the perineal body?
- superficial transverse perineal
- deep transverse perineal
- bulbospongiosus
- levator ani
- sphincter ani externus
Which muscle does not attach to the perineal body?
ishiocavernosus
What is an episiotomy?
- an incision is made from the posterior vaginal wall to the perineal body
- done to prevent uncontrolled tearing of the perineal body and its muscles during parturition
- two ways: median, mediolateral
What is the origin, insertion, nerve supply, and function of the superficial transverse perineal muscle?
- O: ishcial tuberosity
- I: perineal body
- N: perineal branch of pudendal nerve
- F: stabilizes the perineal body
What is the origin, insertion, nerve supply, and function of the ischiocavernosus muscle?
- O: medial surface of ischial tuberosity and ischiopubic ramus
- I: crus of the penis or clitoris
- N: perineal branch of pudendal nerve
- F: impedes venous return, by compressing the crus of the penis or clitoris, thereby maintaining erection
What is the origin, insertion, nerve supply, and function of the bulbospongiosus muscle in the male?
- O: perineal body, median raphe of the bulb of the penis
- I: corpus spongiosum, deep fascia on dorsum of penis
- N: perineal branch of pudendal nerve
- F: impedes venous return by compressing the bulb of the penis, thereby maintaining erection; it also constricts the corpus spongiosum to empty the urethra at the end of micturition and during ejaculation
What is the origin, insertion, nerve supply, and function of the bulbospongiosus muscle in the female?
- O: perineal body, fibers surrounding the bulb of the vestibule and vagina
- I: pubic arch and corpus cavernosum of clitoris
- N: perineal branch of pudendal nerve
- F: constricts the vaginal orifice and maintains erection of clitoris
What are the greater vestibular glands?
- two ovoid glands which are located in the superficial perineal pouch, posterior to the bulb of the vestibule
- their ducts open into the vestibule along the posterolateral margin of the vaginal orifice
- homologous to the bulbourethral gland of the male
- secretes mucus which lubricates the vagina during sexual intercourse