Perineum and external genitalia Flashcards
what are the ANATOMICAL borders of the perineum?
anterior - pubic symphysis
posterior - tip of coccyx
lateral - inferior ischiopubic rami and sacrotuberous ligaments
Roof - pelvic floor (levator ani)
Base - skin and fascia
What are the surface borders in the female perineum?
anterior - Mons pubis
lateral - medial surfaces of the thighs
posteriorly - superior end of intergluteal cleft.
what is the contents of the anal triangle?
anal aperture
external anal sphincter muscle
sischioanal fossae
PUDENDAL NERVE
What are the function of the sischioanal fossae?
they are filled with fat and connective tissue, able to move to the side to allow opening of anal canal for defeacation.
What are the layers of the urogenital triangle?
Deep perineal pouch Perineal membrane superficial perineal pouch perineal fascia skin
what are the superior and inferior borders of the deep perineal pouch?
superior - pelvic floor (levator ani)
Inferior - perineal membrane
what are the superior and inferior boundaries of the superficial perineal pouch?
superficial - perineal membrane
inferior - perineal fascia (superficial to this is the skin)
what does the deep perineal pouch contain in females?
part of urethra, external urethral sphincter and vagina.
what does the deep perineal pouch contain in males?
part of urethra, external urethral sphincter.
Bulbourethral glands.
what is the role of the perineal membrane?
to provide attachment sites to the external genitalia muscles
what is in the superficial perineal pouch?
ischiocavernosis, bulbospongiosis, superficial transverse perineal muscles
Greater vestibular glands in females.
what does the perineal fascia do?
deep - covers the perineal muscles and protruding structures
superficial - superficial layer is continuous with campers fascia, deep layer - continuous with scraps fascia.
what are the anatomical parts of the vulva?
mons pubis labia majora labia minora vestibule bartholins gland
what are the muscles in the female urogenital triangle?
ischiocavernosus
bulbospongiosus (surrounds vaginal opening)
bulb of vestibule (under bulbospongiosus)
bartholins gland
what is the equivalent of the bartholins gland in the male?
Bulbourethral gland.
what are the muscles in the male urogenital triangle?
ischiocavernosus
bulbospongiosus
(Bulbourethral gland is DEEP, so not part).
What are the two main muscles which make up the shaft of the penis?
Corpus spongiosus (1x - contains urethra) Corpus cavernosus (2x, on top, erectile tissue).
what are the 3 main sections of the penis?
Root
body
glans.
which muscle forms the glans penis?
The corpus spongiosum.
what is the opening of the urethra called?
The external urethral orifice.
what are the corpus spongiosum and corpus cavernous also known as?
Corpus spongiosum - bulb of the penis.
Corpus cavernous - left and right crura.
what is the function of the bulbospongiosus?
contracts to empty and urine or semen.
ANTERIOR fibres increase the pressure to aid in erection.
What is the function of. the bulbospongiosis?
surround the left and right crura of the penis
contracts - this forces blood from the cavernous spaces in the crura into the corpus cavernous to maintain erection.
what is the superficial fascia of the penis called?
Colles fascia.
What is the deep fascia of the penis called?
Deep fascia/Bucks fascia.
what is the role of the tunica albuginea in the penis?
forms an individual capsule around each cavernous body then fuses in the midline.
what are the two ligaments of the penis?
Fundiform ligament (sits anteriorly and goes down the shaft) Suspensory ligament (sits posteriorly closer to the root)
what is the role of the suspensory ligament?
attaches the penis to the pubic bone, supports the penis when erect.
what is the role of the fundiform ligament?
thickening of superficial/scarpas fascia
it extends down from the linea alba and surrounds the whole shaft of the penis.
what is the blood supply to the penis?
Branches of the internal pudendal artery.
what is the venous drainage of the penis?
cavernous spaces are drained by the deep dorsal vein of the penis - this empties into the prostatic venous plexus.
superficial dorsal veins - drain superficial structures like skin
what is the nerve supply to the penis?
sensory, motor and sympathetic to skin and glans = branch of pudendal nerve
parasympathetic = cavernous nerves from peri-prostatic nerve plexus (cause erection).
what does the pudendal nerve do to the penis?
sensory, sympathetic and motor innervation.
what do the cavernous nerve do to the penis?
branch of peri-prostatic nerve plexus - parasympathetic, allows erection
What is the ligament below the pubic bones that link them together called?
Arcuate ligament
what is the ligament above the pubic bones called?
Superior pubic ligament
what is the compressor urethrae?
It is only seen in females.
When it contracts it pushes the urethra against the vagina.
Which muscle stabilises the perineal body?
Superficial transverse perineal muscle.
what is the purpose of the ischiocavernosus in both males and females?
contracts - impedes venous return from corpora cavernous - maintains erection.
what external organs/muscles are only found in the female?
- compressor urethrae
- vestibule of vagina
- clitoris (prepuce/ hood)
- bulb of vestibule
- labia minora
- labia majora
what are thhe external organs/muscles only found in males?
Corpus cavernosum Corpus spongiosum bulb of penis glans penis crus of penis
what are the parts of the urethra in males?
pre-prostatic
prostatic
intermediate/membranous
spongy/penile
which structures pierce through the pelvic diaphragm?
anus
urethra
what comes right before the external urethral orrifice?
Navicular fossa.
what is the widest part of the urethra?
Prostatic urethra - receives sperm
what is the narrowest part of the urethra?
membranous/intermediate urethra
what covers the glans penis?
Prepuce (foreskin).
what is the fascia called that covers the corpus cavernosa?
tunica albuginea.
where is the internal urethral sphincter found in females? what’s its nerve innervation?
neck of bladder
autonomic
where is the external urethral sphincter in females? what’s the nerve innervation?
deep perineal pouch
Somatic - pudendal nerve.
where is the external urethra found in males? what’s its innervation?
Just posterior to the prostate
Somatic - pudendal nerve
what is the equivalent to corpus cavernous in females?
the clitoris - comes together as 2 crura which create the body.
what are the fossa called lateral to the anus?
ischioanal fossa.
what does the pudendal nerve do?
provide sensation to the external genitalia, and skin around the anus.
where does the pudendal nerve, internal pudendal artery and vein go after entering the lesser sciatic foramen?
sischioanal fossa.
what is the main tissue in the clitoris?
corpus cavernous
