Perineum Flashcards
Define the following boundaries of the perineum: anterior boundary: lateral boundary: posterior boundary: roof:
anterior boundary: pubic arch (pubic symphosis)
lateral boundary: pubic and ischial rami, ischial tuberosity, sacrotuberous ligament
posterior boundary: sacrum and coccyx
roof: pelvic diaphragm
Where is the anal triangle?
posterior to a line connecting the ischial tuberosities
Describe the anal canal.
arterial supply:
venous drainage:
innervation:
continuation of rectum beyond puborectalism
arterial supply: superior rectal A. above pectinate line, inferior rectal A below pectinate line
venous drainage: superior rectal V. above pectinate line, inferior rectal V. below pectinate line
innervation: autonomic = inferior hypogastric plexus somatic =inferior rectal n.
Describe the internal anal sphincter.
thickened lower end of the inner circular muscle of the rectum
weak sphincter which is not competent acting alone
smooth muscle= inferior hypogastric plexus innervation
Describe the external anal sphincter (3 parts).
subcutaneous- complete circle just deep to skin
superficial- attached posteriorly to coccyx, anteriorly to the perineal body
deep- encircles anal canal and is fused with puborectalis m.
skeletal muscle- innervated by inferior rectal branch of
pudendal nerve
Describe the ischiorectoral fossa.
fat filled space lateral to the anal triangle which is used as dead space for the anus to expand
Describe the lateral, medial, posterior, and anterior walls of the ischiorectoral fossa.
Lateral wall: fascia of obturator internus muscle, sacrotuberous ligament and ischial tuberosity
medial wall: anal canal and levator ani m.
posterior: gluteus maximus and sacrotuberous lig.
anterior: transverse perinei m.
Describe the pudendal canal. (Also known as Alcock’s canal)
formed by fascia of obturator internus below levator ani which splits to enclose the pudendal neurovascular bundle and connects the lesser sciatic foramen to the posterior perineal membrane. (arcus tendineus is above levator ani)
The pudendal canal travels from the lesser sciatic foramen to the deep transverse perineus muscle. The ischial spine marks the posterior limit of the pudendal canal
Describe the Perineal Body.
lies at the front of the anal canal, it is composed of interdigitating fibers of puboprostaticus (pubovaginalis); superficial external anal sphincter, and transversus perinei m.
Describe the nerves of the anal triangle.
pudendal nerve gives off inferior rectal nerve and perineal nerve (perineal is more in UG area though)
pudendal divides at anterior end of anal (triangle to dorsal nerve of penis/clitoris and perineal n)
Describe the vessels of the anal triangle.
Internal pudendal artery and vein
branches include inferior rectal artery and vein
internal pudendeal artery (gives inf. rectal which gives) perineal branch to superficial pouch and continues into deep pouch
Describe the urogenital triangle.
Has perineal membrane which forms the base for penile (clitoral) musculature and penis (clitoris)
space deep to perineal membrane is the deep pouch, the space superficial to the perineal membrane is the superficial pouch
What are the contents of the superficial perineal pouch of the urogenital triangle?
Where is it?
located the area between inferior fascia of UG diaphragm and Colles fascia
CRURA AND BULB:
root of penis/clitoris, erectile tissue
bulb: posterior part of corpus spongiosum (male)
crura: posterior part of corpora cavernosa (one crus, 2 crura. crus of penis/clitoris turns into corpora cavnernosa)
(in female the greater vestibular glands are in s. pouch)
blood supply: deep penile a to crura and artery to the bulb
internal pudendal, perineal
What are the muscles of the superficial perineal pouch?
ischiocavernosus muscle -attaches to ischiopubic rami and surrounds the crura. It contracts to compress venous outflow of penis/maintain erection
Bulbospongiosus m. - surrounds the bulb, acts to expel any remaining urine or semen in the urethra
superficial transverse perineal m
What is different about the female UG triangle?
the bulb and bulbospongiosus m. are split by the vagina
also clitoris has no corpus spongiosum. urethra has nothing to do with clitoris
in male the corpus spongiosum contains urethra running through
What innervates the UG triangle?
perineal n (branch of pudendal nerve.. which also gives off inferior rectal n)
muscular branches
scrotal and labial branches
Describe the arterial supply of the UG triangle.
perineal a. (branch of internal pudendal a.)
muscular branches
scrotal and labial branches
Describe the deep perineal pouch and its contents.
space between perineal membrane and the deep fascia of the levator ani m. (deep pouch is between inferior fascia of UG diaphragm and superior fascia of UG diaphragm)
Contents: membranous urethra bulbourethral glands (male) (Cowper's) ...lubricate urethra before ejaculation
sphincter urethra m.
deep transverse perineus m.
What innervates the deep perineal pouch?
all muscles receive innervation from the muscular branch of the perineal nerve from superficial pouch (S234)
Describe the arterial supply of the deep perineal pouch.
internal pudendal Artery
- muscular branch
- artery to the bulb: pierces the perineal membrane to enter the bulb of penis or clitorus
- deep A. pierces the perineal membrane to reach corposa cavernosa (major erectile body)
- dorsal A. pierces perineal membrane to reach dorsum of penis or clitoris
Describe the veins of the deep perineal pouch.
correspond to the arteries except that the dorsal vein is divided into a deep and superficial dorsal vein
- superficial dorsal vein drains into the superficial external pudendal veins (a branch of femoral v)
- deep dorsal penile vein enters the pelvic cavity by passing above the anterior border of the UG diaphragm and drains into the prostatic plexus of veins
Arrange the fascial planes in order from superficial to deep.
deep fascia (bucks; bulbospongiousus fascia)
skin
deep fascia of UG diaphragm
perineal membrane
deep fascia of pelvic diaphragm
membranous layer of superficial fascia (Scarpa’s, Dartos)
skin
membranous layer of superficial fascia (Scarpa’s Dartos)
deep fascia (bucks; bulbospongiosus fascia)
perineal membrane
deep fascia of UG diaphragm
deep fascia of pelvic diaphragm
What two muscles occupy the deep space?
sphincter urethrae
deep transverse perineus
Where is the ureter relative to the uterine artery?
Water under the bridge!
Ureter travels UNDER the uterine artery.
artery is superficial to ureter
Describe the normal and abnormal orientation of the uterus and lower part of cervix/beginning of vagina.
normal:
uterus- anteflexion
lower part of cervix/beginning of vagina- anteversion
abnormal (could be because of tumor..):
uterus: retroflexed
lower part of cervix/beginning of vagina: (in?)verted
Where are glands located in the male/female UG triangles?
female: greater vestibular gland in superficial pouch
male: bulbourethral gland within deep pouch
What nerve may be blocked for childbirth or surgery?
pudendal
find it by palpating ischial spine (pudendal nerve block site)
Describe the blood supply of the female perineum.
internal pudendal gives: inferior rectal a, dorsal artery of clitoris, perineal artery
dorsal artery of clitoris gives deep artery of clitoris
perineal artery gives posterior labial artery, artery to bulb, muscular branches
Describe the nerve supply of the female perineum.
pudendal nerve gives inferior rectal, dorsal nerve of clitoris, perineal
perineal nerve gives posterior labial and muscular
What is in the deep perineal pouch of the female?
(between perineal membrane below and superior fascia of UG diaphragm above)
vagina, urethra, sphincter urethra, deep transverse perinei
dorsal nerve of clitoris, dorsal/deep clitoral arteries
What is in the superficial perineal pouch of female?
(everything below perineal membrane)
2 crura and ischiocavernosus bulb and bulbospongiousus superficial transverse perinei perineal body perineal artery/nerve/branches vestibular glands
What is in the male deep perineal pouch?
(between perineal membrane below and superior fascia of UG diaphragm above)
membranous urethra deep transverse perinei spinchter urethrae (external spincter) bulbourethral glands (Cowper's) which drain into urethra below the perineal membrane internal pudendal vessels dorsal nerve of penis
Describe how blood investing in the superficial perineal space will be stopped at borders with a straddle injury.
superior border: arcuate line in abdominal wall
lateral borders: inguinal ligaments
deep border: perineal membrane
in male, spread of urine in case of urethral injury would be toward scrotum, penis and anterior abdomen
(blood collects between Colle’s fascia and rectus sheath?)
Arcus tendineus is between what 2 muscles?
Obturator internus
levator ani
(it is above the levator ani)
Describe the path of the pudendal artery/nerve.
leaves greater sciatic foramen, loops around ischial spine and comes back in lesser sciatic foramen to reach perineum
What are the roots of the sciatic nerve?
What are the roots of the femoral nerve?
sciatic- L4,5 and S1,2,3
femoral-L2,3,4
What does Scarpa’s fascia turn into in the perineum?
Colle’s fascia
