Perineum and External Genitalia Flashcards
Layers of the perineum
External genitalia
Perineum
Pelvic diaphragm
Anatomical position of the perineum
the narrow region between the proximal part of the thighs, does not include inner aspect of thigh
Lithotomy postion of the perineum
diamond shaped area extending from the pubic symphysis to the coccyx
Overlies the inferior pelvic aperture
perineum
An imaginary transverse lkine jining the internal aspects of the ischial tuberosities produces?
two triangles: urogenital and anal triangle
Closed by a sheet of tough fascia called the perineal membrane
Urogenital Triangle
Fxn of the urogenital triangle
provides a foundation for the erectile bodies of the external genitalia
Contains the external urogenital structures
Urogenital Triangle
Contains the anal canal and anus surrounded by ischioanal fat
Anal Triangle
Potential space between the membranous layer of the subcutaneous tissue (perineal fascia) and the perineal membrane
Superficial Perineal Space (SPS)
bounded laterally by the ischiopubic rami, space
SPS
Contents of the superficial perineal space
Root (bulb and crura of penis, crura of clitoris)
Muscles: ischiocavernosus, bulbospongiosum, superficial transverse perineal muscles
3 superficial arteries and veins
Male: bulb of spongy urethra, bulbocavernosus galnds, intrenal pudendal and pudendal (perineal nerve) branches
Female: Bartholin’s gland, vestibular glands , related vessels and verves (internal and perineal nerve) Crura, vaginal orifice
Forces blood from cavernous spaces in crura into distal parts of corpora cavernosa increasing turgidity of penis during erections
Ischiocavernosus muscle
Muscle made up of longitudinal fibers
Ischiocavernosus muscle
compresses teh bulb of penis and corpus spongiosum
Bulbospongiosus or bulbocavernosus
aids in emptying spongy urethra of residual urine or semen
Bulbospongiosus or bulbocavernosus
anterior fibers assist in erection by increasing pressure on erectile tissue in the root of the penis
Bulbospongiosus or bulbocavernosus
Muscle made up of transverse fibers
Bulbospongiosus or bulbocavernosus
supports perineal body to aid pelvic diaphragm in supporting pelvic viscera
superficial transverse perineal muscles
area between STP and ischiocavernosus
perineal membrane
Secrete mucus to lubricate the vaginal canal? also called what?
Bartholin’s gland/ Great vestibular Glands
T/F structures of Males in the SPS is bigger than if females
True (penis>clitoris)
provides further support for urogenital structures, especially for females after childbirth
DPS or Deep Perineal Space
Boundaries of DPS
Inferior: Perineal membrane
superior: Inferior fascia of the pelvic diaphragm
Lateral: inferior portion of the obturator fascia
Contents of DPS
Urogenital Diaphragm: Spincter urethrae, deep transverse perinea/urogenital sphincter
Nerves: dorsal nerve to the penis or clitoris
Arteries and Veins: Deep dorsal vein of the penis/clitories, internal pudendal artery and its branches
Males only: Cowper’s gland/bulbourethral gland/great vestibular gland
Most prominent vein in the DPS
deep dorsal vein of the penis/clitoris
Terminal branch of the internal pudendal artery
dorsal vein of the penis/clitoris
lubricate and cleanse the urethra during ejaculation
Cowper’s gland/bulbourethral/great vestibular gland
homologous to bartholin’s gland
Cowper’s gland/bulbourethral/great vestibular gland
Posterior Triangle of the perineum
Ischiorectal fossa
Boundaries of the ischiorectal fossa
Anterior: base of UG diaphragm and fascia
Posterior: gluteus maximus, sacrotuberous ligament
lateral: ischium, obturator iternus and fascia
medial: anal canal and rectum
supermedial: levator ani
Contents of ischiorectal fossa
FAT
inferior rectal vessels and nerve
perforating cutaneous branches of S2, S3
perineal brach of S4
Parts of the external anal sphincter
deep: circular; overlaps internal sphincter
subcutaneous: circular
superficial: elliptical (central tendon to tip of coccyx)
surrounds lowest part of anal canal
External Anal Sphincter
The perineal body is especially impt for which sex?
Female - parturition/childbirth
Stretching or tearing the attachments of the perineal body may cause
prolapse of the bladder/uterus
midpoint of the line joining the ischial tuberosities
central point of the perineum
What is the central point of the perineum made up of
fascia
What muscles converge on the central point of the perineum?
bulbocavernosi
superficial tranverse perinea
external anal sphincter
levator ani
Determines whether or not to undergo episiotomy
Central pt of perineum
Surgical insicsion of the perineum and interposterior vaginal wall
episiotomy
No muscles are transversed, only the tendinous parts are cut thru the central pt
midline episiotomy
midline episiotomy is performed only when the length of the perineal body is
3cm
Fast healing;minimal bleeding episiotomy
midline
muscles are severed so it’s more painful and takes longer to heal
mediolateral episiotomy
mediolateral episiotomy transects
skin, vaginal mucosa, bulbocavernosus, superficial transverse perineal, possibly levator ani
T/F: mediolateral episiotomy is done with anesthesia?
False. It is done simultaneously with uterine contractions
When is mediolateral episiotomy done?
When perineal body is less than 3cm
Degrees of laceration
1st to 4th
1st: perineal skin and vaginal mucosa. no muscles
2nd: bulbocavernosus and STP
3rd: external anal spincter
4th: anterior rectal canal
May result in retrovaginal fistula
4th degree perineal laceration
Primary fxn of external genitalia
copulation and parturition
Genital swellings of the male move in what direction fromt eh inguinal region to form the what?
caudally, scrotal swellings
At what point can the sex of the baby be determined?
18weeks
Genital tubercle of the male baby becomes?
phallus
Urethral folds pulled forward by phallus (male) becomes
lateral walls of urethral groove
In females, the genital tubercle becomes
clitories
urethral folds in females do not fuse because
they become the labia minora
genital swellings in females enlarge to become
labi majora
In females, what can be seen to determine that it is indeed female in the ultrasound
3 light lines that corresponds to labia majora, labi minora and vestibular slit
The male copulatory organ
penis
the common outlet for urine and semen
penis
T/F the clitoris has both the corpora cavernosa and corpora spongiosum
False. clitoris only has corpora cavernosa.Penis has both
Most sensitive part of the penis due to attachment to underlying erectile tissue
skin
dorsal part removed during circumcision
prepuce
fold on ventral surface from urethral meatus to corona, not removed during circumcision
frenulum
In the cavernous bodies, which is paired, which is not?
cavernosa - paired
spongiosum - unpaird, ventral, contains spongy urethral meatus
Penis has 2 parts: enumerate
root (attached part): crura, bulb of the penis, ischio ang bulbo muscles
mobile part: body, glans, corona, external urethral meatus
swollen front end of corpus spongiosum
glans
for maintainance of erection and initiation of ejaculation
abundant cutaneous nerves in the glans
Most sensitive portion of the penis
glans
Fascia of the penis
Tunica albuginea
Buck’s fascia (deep fascia)
Suspensory ligament of the penis
Fascia enclosing each corpus/cavernous body
tunica albuginea
Encloses all three tissues (corpus bodies)
Buck’s fascia
Where are the internal pudendal vessels located?
Between buck’s fascia and tunica albuginea
fibromuscular sac for the testis and associated structures
Scrotum
What enables the scrotum to reduce heat loss?
Tunica Dartos/Dartos muscle
CT continuous with subcutaneous tissue and Colle’s fascia
Tunica Dartos
Midline of the scrotum
scrotal raphe
Fxns of the testes
contracts towards body when cold, relaxes away when warm
produce sperm in seminiferous tubules
sperm viability is maintained at what temp
34C
testes are suspended in the scrotum by
spermatic cords
Which testes is suspended more inferiorly?
Left testes
Testosterone producing cells
leydig cells
remains of the peritoneum that covers the testis
tunica vaginalis
tough fibrous outer surface that thicken into the ridge as the mediastinum of the testis
tunica albuginea
Cause of congenital or indirect hernia
if the processus vaginalis remians patent
presence of excess fluid in a persistent processus vaginalis
hydrocoele
vine-like pampiniform plexus of veins may become varicose (dilated) and tortuous
varicocoele
Varicocoeles of which side is more common?
Left side
Promote sperm maturation by secretion of protein
Epididymis
T/F Sperm maturatin occurs in the testes
False. Sperm maturation occurs in the epididymis
Parts of the epididymis and their fxns:
head: sperm motility
body: fertilizing ability
tail: storage
Female external genitalia also called
pudenda/ vulva
Functions of external female genitalia
a sensory and erectile tissue for sexual arousal and intercourse
directs the flow of urine
prevents entry of foreign material into the urogenital tract
for parturition
Mon pubis fat amount
fat amt increases at puberty, decreases after menopause
Contents of the labia majora
termination of the round ligament
ilioinguinal nerve
anterior labial vessels
labia minora is situation within the
pudendal cleft
structures that open into the vestibule
urethra
vagina
bartholin’s gland
bulbs of the vestibule
T/F: During a vulvectomy, all parts of the pudenda are removed
True
External female genital subcutaneous tissue
Camper’s and Colle’s/Scarpa’s
