Ach: Perineum Flashcards
Where is the perineum located?
INFERIOR to the pelvic diaphragm in the pelvic outlet
What does structures does the perineum contain?
external genitalia
terminal portions of urogenital system and GI tract
What are the boundaries of the pelvic outlet?
Pubic arch: tip of the coccyx
Lateral: Inferior ramus of pubis and ischium and sacrotuberous ligaments
What is the UG triangle?
ANTERIOR to the transverse line
What is the anal triangle?
POSTERIOR to the transverse line
Where is an important support for the pelvic floor?
the central tendon of the perineum is a point where several muscles of the perineum insert
What are the two layers of the superficial perineal fascia?
- Superficial fatty layer
2. Membranous layer/colles fascia (continuous w/ Scarpa’s in the abdomen)
The superficial fatty layer of fascia is continuous with….
fascia in the:
abdomen
thigh
anus
How does the superficial fatty layer differ in the female body from the male?
F: continues into the labia majora and inserts near the perineal body
M: fatty layer less in UG triangle, continues around penis into scrotum where fat is replaced by smooth muscle (dartos muscle)
Where does the membranous layer of the superficial perineal fascia attach?
Ischiopubic rami laterally
Fascia lata of hte ghigh
posterior border of the UG diaphrgam
What happens to the membranous layer in the male?
It fuses w/ the superficial fatty layer anteriorly–> dartos fascia that surrounds the scrotum and the penis
the fat is replaced by smooth muscle called the dartos muscle
What is colles fascia?
separates the dartos fascia at the base of the penis and continues to the UG diaphragm
The superficial perineal fascia is an extension of…
the superficial fascia of the anterior abdominal wall
What are the two layers of the deep perineal fascia?
- Deep perineal (gallaudet’s fascia)
2. deep fascial layer (buck’s fascia)
What does the deep perineal fascia consist of?
Consists of the investing layer (gallaudet’s fascia) surrounding muscles in the superficial perineal pouch and the deep fascial layer (buck’s fascia) over the erectile bodies of the penis
What is the perineal membrane?
thin sheet of deep fascia
attached to the ischiopubic rami laterally
Pierced by the urethra in the male and the rethra and vagina in the female
What are the two pouches in the UG triangle?
- Superficial perineal space (between the membranous layer of the superficial fascia and the perineal membrane)
- Deep perineal space (opens superiorly and is bounded below the perineal membrane)
What is found in the superficial perineal pouch?
- Erectile bodies
- Superficial trnasverse perineal muscle
- vessels and nerves of muscles
- Greater vestibular glands in the female
What are the erectile bodies?
crura
bulb of the penis
bulb of the clitoris
What muscles cover the crura and the bulb?
crura-ischiocavernosus
bulb-bulbospongiosus
What does the superficial transverse perineal muscle do?
stabilizes perineal body
What vessels /nerves supply the superficial perineal pouch?
internal pudendal artery
pudendal nerve
What is essential for the integrity of the pelvic floor?
perineal body/central tendon of the perineum that’s a midline fibromuscular mass between the UG and anal triangles
Where is located in the deep perineal pouch?
- deep transverse perineal muscle
- sphincter uretrhae muscle
- compressor urethrae muscle
- urethra
- internal pudendal vessels, pudendal nerves and their branches
What penetrates hte deep perineal pouch in the female?
vagina
What glands are located in the deep perineal pouch in hte male?
bulbourethral (cowpers)
The deep perineal pouch and its contents is also called the….
UG
What is the penis composed of?
3 cylindrical bodies of erectile tissue
enclosed by dense tissue
forms capsule called tunica albuginea
What is the corpora cavernosa in the penis?
begins as the crura of the penis
located ventrally dorsally
What does hte corpus spongiosum begin as and where is it located?
as the BULB of the penis that expands distally to form the glans penis.
located ventrally
Where is the root of hte penis found?
superficial perineal space
How long is the urethra?
20 cm
What are three portions of the urethra?
1) prostatic: penetrates prostate
2) membranous: that portion which traverses the deep perineal pouch and is surrounded by the sphincter urethrae muscle.
3) spongy or penile: that portion found in the corpus spongiosum.
What fascia covers the penis?
- Superficial
2. Deep (continuous w/ the external spermatic fascia in the scrotum and the suspensory ligament of the penis)
What is the mons pubis?
eminence over the pubic bone (mons veneris)
what are the labia majora and minora?
outer and inner folds of skin that extend posteriorly from the mons
What is the clitoris composed of?
erectile tissue composed of two CRURA (coversed by ischiocavernosus muscles), a body and a glans
Does the clitoris contain corpus spongiosum?
NO b/c it’s NOT traversed by the urethra
What are the frenulum and the prepuce?
Parts of the clitoris that are parts of the labia minora that pass posterior and anterior to the clitoris
What is the vestiblue?
area posterior to clitoris and between labia minora; openings of vagina, urethra, and greater vestibular glands.
What is the hymen?
membrane of variable size and found partly blocking the vaginal orifice.
What are the bulbs of the vestibule?
two masses of erectile tissue that lie along the vaginal orifice; covered with bulbospongiosus muscles
What is the ischioanal fossae?
A wedge-shaped area on either side of the rectum located between the skin and the pelvic diaphragm
What are the boundaries of the anal triangle?
1) laterally: obturator internus and fascia
2) medially: anal canal
3) posteriorly: sacrotuberous ligament and gluteus maximus
4) anteriorly: base of UG diaphragm and fascia
5) superiorly: levator ani
What forms the pudendal canal and what does it contain?
obturator internus fascia
internal pudendal artery and the pudendal nerve
What are the branches of the internal pudendal artery?
inferior rectal artery
perineal artery
What forms the sacral plexus?
pudendal nerve (S2,3,4)
Where is the pudendal nerve lcoated?
The pudendal nerve passes through the greater sciatic foramen, crosses the ischial spine and enters the perineum through the lesser sciatic foramen with the internal pudendal artery. It then enters the pudendal canal, gives off the inferior rectal nerve and terminates as the perineal nerve and the dorsal nerve of the penis (clitoris).
What nerve supplies the external anal sphincter?
inferior rectal nerve
What nerve supplies all the muscles of the perineum and gives off a superficial scrotal or labial nerve to supply the posterior scrotum or labium?
perineal nerve (terminal branch of pudendal)
What nerve pierces the perineal membrane and runs deep to the deep fascia on the dorsum of the penis or clitoris to supply the skin, prepuce, and glans?
Dorsal nerve of the penis/clitoris (terminal branch of pudendal)
What’s a straddle injury?
bruising to tearing to nerve damage to fracture of pubic rami
How does bicycling cause erectile dysfunction?
poor seat design puts pressure on pudendal nerve and artery branches>
Numbness or pain after a long ride
Altered sensation of micturition, defecation and ejaculation
c. Chronic pressure can lead to localized atherosclerosis of pudendal vessels, compromised blood supply and erectile dysfunction.
How does chronic pressure on the pudendal nerve lead to erectile dysfunction?
It can cause localized atherosclerosis of pudendal vessels, compromised blood supply and erectile dysfunction
Where does the urine go if a ruptured urethra does NOT penetrate Buck’s fascia?
confined to penis
What happens to the urine if a urethral rupture does perforate buck’s fascia?
Urine will spread beneath colles fascia in the penis, scrotum, anterior abdominal wall, but NOT the thigh b/c of the attachment of this fascia to the fascia lata
What is an episiotomy?
prevent tears of the perineum and to ease delivery of the fetus, a small relaxing incision is made in the perineum, either directly posterior to the opening of the vagina or somewhat lateral. Midline incisions heal better
What is a pudendal nerve block?
provides anesthesia to the skin, muscles and deeper structures of the perineum to relieve pain from childbirth and permit episiotomy.
Also, a block will produce relaxation of all the perineal muscles and reduce the possibility of laceration.
Where is a pudendal nerve block given?
Feel for the ischial spine to locate the pudendal nerve
