11/17 Perineum Anatomy Flashcards
what is the perineum
shallow, diamond-shaped region inferior to the pelvic diaphragm
what kind of boundaries does the perineum have
osseofibrous
two triangles of the perineum
anal and urogenital
does the shape of the perineum change?
yes, with lower extremity movement
perineum function
to support gastrointestinal, urinary, and genital viscera
boundaries of the perineum
pubic symphysis, ischiopubic ramus, ischial tuberosity, sacrotuberous ligament, coccyx
is the urogenital triangle sexually dimorphic?
yes
urogenital triangle contents
urethrae, vagina, erectile bodies, muscles, glands, neurovasculature, minimal adipose
anal triangle contents
anal canal, anus, minimal neurovasculature, substantial adipose tissue
what is the palpable central point of the perineum?
perineal body
perineal body
subcutaneous, irregular mass of collagen, elastic fibers, and interlacing skeletal and smooth muscles
when is the perineal body formed embryologically?
when the urorectal septum partitions the cloaca
perineal body function
provides passive support for pelvic viscera
what is the perineal membrane?
a dense, tough sheet of fascia attached to ischiopubic rami; posterior edge is attached to perineal body centrally
what does the perineal membrane cover?
the anterior pelvic outlet
perineal membrane functions
passive support for pelvic viscera
attachment sites for erectile bodies and musculature
divides urogenital triangle into superficial and deep pouches
where does perineal neurovasculature travel
through the pudendal canal
what is the pudendal canal
a horizontal canal within obturator fascia, between obturator internus and ischioanal fossa
pudendal nerve comes from
ventral rami of S2-4
pudendal nerve branches do what
innervate the majority of the perineum’s skin, muscle, and organs
internal pudendal artery supplies?
branches supply the perineum with minor assistance from external pudendal artery
what is the ischioanal fossae
wedge-shaped space on either side of anal canal filled with adipose tissue
why is the ischioanal fossa filled with adipose tissue
to support anal canal and permit deformation for the passage of feces
what does the ischioanal fossa contain
inferior rectal neurovasculature
anal canal contains
anal columns, valves, and sinuses/crypts
anal canal function
to contain glands that exude mucus
anal verge is
junction of anal epithelium and skin
pectinate line
visible scalloped line in anal canal
what does the pectinate line mark
difference in embryological origin (hindgut endoderm or proctodeum ectoderm)
internal anal sphincter location
thickened layer of intestinal wall around superior 2/3 of anal canal
external anal sphincter location
inferior 2/3 of anal canal
the internal anal sphincter control
under sympathetic control for constant tone
the external anal sphincter controlled by
under somatic control
ischioanal/ischiorectal abscess is?
abscess that has penetrated through the external anal sphincter and into the ischioanal fossa
etiology of ischioanal abscess
infected anal sinus/crypt (could be from chronic constipation, trauma, STI)
internal hemorrhoids
varicosities of superior rectal veins internal venous plexus, covered in mucous membrane
external hemorrhoids
varicosities of inferior rectal veins external venous plexus, covered in skin
what is anatomical position of penis
erect
male external genitalia
scrotum, penis, prepuce (foreskin)
parts of penis
shaft, distal urethra, external urethral orifice, glans, fascia, neurovasculature
penis shaft is made up of
3 cylindrical, fused erectile bodies
3 erectile bodies of male genitalia
corpus spongiosum, corpora cavernosa x2
each male erectile body has
a tunica albuginea, with deep fascia of the penis binding them all together
4 parts of the male urethra
preprostatic/intramural, prostatic, intermediate/membranous, spongy
female external genitalia
vulva
vulva parts
mons pubis, labia majora, labia minora, vestibule, 3 erectile bodies, prepuce, fascia, neurovasculature
vestibule contains
vaginal orifice and external urethral orifice
3 erectile bodies of female genitalia
bulbs of vestibule x2
clitoris
erectile bodies anatomy
crura attach to ischiopubic rami and are supported by perineal membrane, covered in musculature proximally
during erection what do erectile bodies do?
blood flow increases and the surrounding muscles compress the erectile bodies to inhibit venous return
function of erection in males
to fill with enough pressure to cause and maintain erection
function of erection in females
to increase sensitivity of vaginal orifice and surrounding tissues; to create swelling of vulva
types of perineal fascia
superficial and deep
types of superficial perineal fascia
superficial/fatty
deep/membranous
What is the superficial perineal fascia (fatty layer) continuous with anteriorly and posteriorly?
anteriorly blends with abdominal camper fascia
posteriorly blends with ischoanal fat and thighs
what does the fatty layer of the superficial perineal fascia help form in females?
mons pubis and labia majora
What is the superficial perineal fascia (deep layer) continuous with?
fuses with perineal membrane and deep fascia of thighs
anteriorly, blends with abdominal scarpa fascia
what does the deep layer of the superficial perineal fascia blend with in males?
dartos fascia
What is the deep perineal fascia continuous with?
fuses with ischiopubic rami and suspensory ligament of penis/clitoris
forms investing fascia of muscles in superficial perineal pouch
blends with abdominal deep fascia superiorly
male contents of superficial perineal pouch
root of penis and associated muscles
proximal spongy urethra
superficial transverse perineal muscles
posterior scrotal neurovasculature
female contents of superficial perineal pouch
clitoris, bulbs of vestibule, and associated muscles
greater vestibular glands
superficial transverse perineal muscles
posterior labial neurovasculature
what are the associated muscles contained in both male and female superficial perineal pouches?
bulbospongiosus
ischiocavernosus
superficialtransverse perineal muscles
male contents of deep perineal pouch
intermediate urethra
external urethral sphincter
bulbourethral glands
deep transverse perineal muscles
neurovasculature of the penis and bulb of the penis
anterior part of ischioanal adipose tissue
female contents of deep perineal pouch
proximal urethra
external urethral sphincter
part of vagina
smooth muscle associated with perineal body
neurovasculature of clitoris and bulb of vestibule
anterior part of ischioanal adipose tissue
perineal lacerations etiology
often from childbirth
function of bulbourethral glands
to exude alkaline mucus during sexual arousal for lubrication and to neutralize urine
extravasation of urine
damage to the urethra leading to ectopic urine collection
etiology of extravasation of urine
stricture, calculi, trauma
rupture of intermediate urethra causes accumulation of what and where?
urine/blood travels into deep perineal pouch
can spread extraperitoneally
rupture of spongy urethra causes accumulation of what and where?
urine/blood travels into superficial perineal pouch
can spread into penis, scrotum, anterior abdominal wall
if the female urethra is damaged, the effects would be similar to a rupture of which region of the male urethra?
intermediate
difference between male and female lymphatic drainage of perinea
females have sacral lymph nodes, males do not
male lymphatic drainage
female lymphatic drainage
