Perineum 1 & 2 Flashcards
What is perineum bounded by (3)?
1) coccyx
2) ischial tuberosities
3) pubis
A line through which structure divides perineum into 2 triangles?
ischial tuberosities
What two triangles can perineum be divided into?
1) anal triangle
2) urogenital triangle
Which of the two triangles is anterior and which is posterior?
anterior –> urogenital
posterior –> anal
Which triangle includes anal canal and paired ischioanal fossae?
anal triangle
Which triangle includes external genitalia?
urogenital
The anal canal is the terminal part of large intestines, it runs from ____ ____ to ___
pelvic diaphragm to anus
How is the anal canal divided?
upper and lower halves
What divides anal canal?
pectinate line (based on embryologic development)
Which half is derived from endoderm?
upper
What type of epithelium lines the upper half of anal canal?
columnar
What marks the anorectal junction?
vertical folds = anal columns
Where is the pectinate line in relation to anal columns?
inferior
What structure is found in anal columns?
semilunar folds (or anal valves)
What type of innervation does the upper anal canal have?
autonomic
What arteries supply the upper half of anal canal?
1) superior rectal a (from IMA)
2) middle rectal a (from internal iliac a)
Where do blood drain in the upper half of anal canal?
superior rectal vein (then into IMV)
Where do lymphatics travel to in the upper half of anal canal?
superiorly to inferior mesenteric nodes
What germline is the lower half of anal canal derived from?
ectoderm
What type of epithelium does the lower half of anal canal have?
stratified squamous
Are anal columns present in the lower half of anal canal?
No
What type of innervation does the lower half of anal canal have?
somatic
Which nerve innervates lower half of anal canal?
inferior rectal branch of pudendal n
What artery supplies the lower half of anal canal?
inferior rectal a (from internal pudendal a)
Where do blood drain to in the lower half of anal canal?
inferior rectal v (then to internal pudendal v)
Where do lymphatics travel to from the lower half of anal canal?
inferiorly to superficial inguinal nodes
True or False. There is an internal and external anal sphincter
True
Which anal sphincter is made up of smooth muscle and which is of skeletal muscle?
internal –> smooth
external –> skeletal
Which anal sphincter is voluntary and which is involuntary?
internal –> involuntary
external –> voluntary
True or False. The internal anal sphincter is the thickening of outer circular muscular coat at proximal anal canal.
FALSE. it is the thickening of INNER circular muscular coat
What innervates the external anal sphincter?
inferior rectal n.
What is the fat-filled space lateral to anal canal called?
ischiorectal (ischioanal) fossa
What are the boundaries to ischiorectal fossa (5)?
1) skin
2) levator ani
3) obturator internus
4) sacrotuberous and sacrospinous ligaments
5) deep transverse perineal muscles
What is the significance of the fat-filled ischiorectal fossa?
permits distension of anal canal
Where is pudendal canal located?
fascial canal on lateral wall of fossa
What is located in pudendal canal?
1) pudendal nerve
2) internal pudendal artery
3) internal pudendal vein
What spinal level is pudendal nerve?
S2-S4
All contents of pudendal canal enters through…
lesser sciatic foramen
Pudendal nerve exits the pelvis via ___ and enters perineum via ___
exits –> greater sciatic foramen
eneters –> lesser sciatic foramen
What are the branches of pudendal nerve?
1) inferior rectal
2) dorsal nerve of penis or clitoris
3) perineal nerves
Which artery gives rise to internal pudendal artery?
internal iliac a
What are the branches of internal pudendal a?
1) inferior rectal
2) branches to penis or labia and clitoris
What are hemorrhoids?
dilated veins in anal canal
Where are internal hemorrhoids located?
upper half of anal canal
Where are external hemorrhoids located?
lower half of anal canal
What are the different fascia in urogenital triangle?
1) superficial fascia (fatty layer)
2) superficial fascia (membranous layer - Colles fascia)
3) deep fascia (investing fascia)
The fatty layer of superficial fascia is continuous with ____
ischiorectal fat
In females, the fatty layer makes up substance of fat in ____ and ____
mons pubis and labia majora
The membranous layer in urogenital triangle is called _____ in abdomen
Scarpa’s fascia
The fatty layer in urogenital triangle is called ____ in abdomen
Camper’s fascia
What forms tubular sheath around penis and clitoris?
Colles fascia (membranous layer)
What layer envelopes muscles of perineum?
deep fascia
The deep fascia is fused to _____ of penis or clitoris
suspensory ligament
The deep fascia in urogenital triangle is continuous with what layer in abdomen?
fascia of external oblique and rectus sheath
What holds penile corpora together?
deep penile fascia (Buck’s fascia)
Deep penile fascia is continuous of what?
deep fascia of urogenital triangle
Potential space between membranous/Colles fascia and perineal membrane
male superficial perineal pouch
Thin inferior fascia of urogenital diaphragm
perineal membrane
What are the contents of male superficial perineal pouch (5)?
1) root of penis (bulb and crura)
2) ischiocavernosus m
3) bulbospongiosus m
4) superficial transverse perineal m
5) spongy urethra
Space between superior fascia of urogenital diaphragm and perineal membrane
male deep perineal pouch
The male deep perineal pouch is essentially filled by …
sphincter urethrae and transverse perineal muscles
What are the contents of male deep perineal pouch (6)?
1) membranous urethra
2) external urethral sphincter
3) bulbourethral (Cowper’s) gland
4) deep transverse perineal m
5) dorsal nerve of penis
6) internal pudendal arterial branches
Which perineal pouch is easily ruptured?
male deep perineal pouch
What are the contents of scrotum?
1) testes
2) epididymis
3) spermatic cord
Which fascia attaches to and contains dartos muscle?
membranous fascia (Colles)
What type of muscle is dartos muscle?
smooth
What is the function of dartos muscle?
wrinkling and expanding of skin of scrotum
What innervates scrotum?
genital branch of genitofemoral
What surrounds corpora cavernosa and corpus spongiosum of penis?
runica albuginea
What is known as erectile bodies?
corpora cavernosa and corpus spongiosum
What binds erectile bodies together?
deep penile fascia (Buck’s fascia)
What surrounds penis externally underneath the skin?
superificial penile fascia (Colles/membranous)
What are the three cylindrical erectile tissue in root of penis?
1) bulb - corpora spongiosum
2) right and left crura - corpus cavernosum
What is the bulb from root of penis attached to?
perineal membrane of urogenital diaphragm
What is right and left crura from root of penis attached to?
ischiopubic rami
True or False. Body of penis is continuation of erectile tissues from the root of penis
True
What erectile tissue contains urethra?
corpus spongiosum
What expands at its terminal end to form glans penis?
corpus spongiosum
What paired muscles are attached to each other at median tendinous raphe?
bulbospongiosus muscles
What occurs when bulbospongiosus muscles contract?
compress bulb
1) aids in emptying spongy urethra of residual urine/semen
2) erection by increasing pressure on erectile tissue in the root and compressing venous return
Which paired muscles cover the right and left crus?
ischiocavernosus muscles
What occurs when ischiocavernosus muscles contract?
compress each crus and aids in achieving and maintaining an erection via the compression of the crura and by retarding venous recturn
What are the small muscles that arise from ischial tuberosity and inserting into perineal body?
superficial transverse perineal muscles
Which muscles fix the perineal body?
superficial transverse perineal muscles
What is the small fibrous mass in center of perineum?
perineal body
What structures attach to perineal body?
1) external anal sphincter
2) bulbospongiosus
3) superficial transverse perineal muscles
What innervates perineal muscles and skin?
perineal branches of pudendal nerve
What are the muscles of perineum?
1) ischiocavernosus
2) bulbospongiosus
3) superficial transverse perineal
Which part of the urethra is the smallest and narrowest?
membranous
What innervates external sphincter of urethra?
perineal branch of pudendal n
True or False. external sphincter of urethra is a voluntary muscle
True
What are the ducts of the glands extend into superficial perineal pouch to enter spongy urethra?
bulbourethral (Cowper’s) glands
What produces a few drops of fluid that cleanse the urethera and provide lubricating fluids for sexual activity?
bulbourethral glands
What muscle is posterior to sphincter urethrae and extends from ischial rami to perineal body?
deep transverse perineal muscle
What innervates skin of penis and glans penis?
dorsal nerve of penis
Deep arteries of the penis fill which erectile tissue with blood that aids in erection?
corpora cavernosa
What is the origin of deep arteries of penis?
internal pudendal a
What opens into cavernous spaces, coiled arteries in flaccid penis?
helicine branches
What structure in the female body is the terminal part of round ligamen?
labia majora
Labia major is prominent folds of skin, what is its function?
protection
What is labia majora filled with?
fat and smooth muscle
What are lies medial to labia majora and has delicate mucus membrane folds?
labia minora
Which structure forms the prepuce and frenulum?
labia minora
What is the space between labia minora?
vestibule
What are the contents of vestibule?
1) external meati of urethra
2) vagina
3) ducts of greater and lesser vestibular glands
The clitoris has two parts, what are they?
1) root
2) body
Which part of the clitoris is the attached portion in superficial perineal pouch?
root
What does the root of clitoris contain?
1) bulb of vestibule
2) R and L crura
Bulb of vestibule is homologous to which structure in males?
bulb of penis and corpus spongiosum
How is bulb of vestibule divided?
2 parts: surrounding vaginal and urethral orifice
Just like males, right and left crura is ____ in females
corpora cavernosa
What does right and left crura attach to in females?
pubic arch
Which part of clitoris is proximally detached?
body
What does the body of clitoris consist of?
corpora cavernosa
What muscle covers bulb of vestibule?
bulbospongiosus muscles
What muscle covers crura of clitoris?
ischiocavernosus muscles
Which muscle aids in erection of clitoris?
ischiocavernosus muscles
What glands secrete lubricating mucus during sexual activity in females?
greater vestibular glands
Where do greater vestibular glands open into?
vestibule, posterolateral to vaginal orifice
Which structure of the female body corresponds to male’s prostate?
lesser vestibular glands
Where do lesser vestibular glands open into?
vestibule, lateral to urethral orifice
Mucus secreted by lesser vestibular glands is for distribution to…
labia and vestibule
What are the contents of female superficial perineal pouch?
1) root of clitoris
2) muscles covering bulb and crura
3) greater vestibular glands
4) lesser vestibular glands
5) superficial transverse perineal muscles
6) perineal body
7) perineal branches of pudendal n
What are the contents of female deep perineal pouch?
1) part of urethra
2) part of vagina
3) sphincter urethrae
4) deep transverse perineal muscles
5) internal pudendal vessels, arterial branches
6) dorsal nerves of clitoris
What is the origin of dorsal nerves of clitoris?
pudendal n
What structure do dorsal nerves of clitoris supply?
clitoris
True or False. Internal urethral sphincter is present in both sexes.
False. only in males
What type of muscle do internal and external urethreal sphincters have?
internal –> smooth
external –> skeletal
What are the three sexual function of perineal organs in males?
1) erection
2) emission
3) ejaculation
What type of innervation controls erection?
parasympathetic
What type of innervation controls emission?
sympathetic
What type of innervation controls ejaculation?
somatic (also autonomic)
Where do nerve fibers originate from in parasympathetic innervation of erection?
pelvic splanchnic nerves (S2-S4)
What do parasympathetic fibers control during erection?
dilate helicine arteries, filling cavernous tissues with blood
How do bulbospongiosus and ischiocavernosus muscles assist during erection?
by compressing venous plexus, impeding venous return
Where do nerve fibers originate from in sympathetic innervation of emission?
L1-L2
What do sympathetic fibers control during emission?
1) movement of semen into prostatic urethra
2) peristalsis of ductus deferntes and seminal vesicles
3) prostatic contraction
What does prostatic contraction accomplish?
adds prostatic fluid
What glands are involved in emission?
1) seminal vesicles
2) prostate
3) bulbourethral glands
What do somatic nerve fibers control during ejaculation?
expulsion of secretions and spermatozoa
Ejaculation is affected by rhythmic contractions of which muscles?
bulbospongiosus and ischiocavernosus muscles
What nerve innervate the process of ejaculation?
S2-S4 –> pudendal n
How do autonomic nerve fibers contribute during ejaculation?
sympathetics –> close internal urethral sphincter
parasympathetics –> contract urethral muscle
