Male and Female Perineum Flashcards
What is the most inferior region of the trunk?
What 2 general structures are contained in this region?
perineum
external genitalia and anal canal
What are the boundaries of the diamond-shaped perineum?
lateral: ischiopubic rami and sacrotuberous ligaments
posterior: coccyx
anterior: pubic symphysis
superior limit: pelvic diaphragm, separates from pelvic cavity
inferior boundary: surface of skin of external genitalia and anal canal
The perineum can be divided into two triangles by drawing a line between what bilateral feature?
ischial tuberosities
What are the 2 triangles of the perineum
urogenital
anal
What are the boundaries of the urogenital triangle?
pubic symphysis
ischiopubic rami
imaginary line b/w ischial tuberosities
What are the boundaries of the anal triangle?
coccyx
sacrotuberous lig
imaginary line b/w ischial tuberosities
What are the 2 contents of the anal triangle?
- ischiorectal (ischioanal) fossae
2. anal canal
What fills the ischiorectal fossae?
Where are they located?
filled w/ fat
Wedge shaped spaces on either side of the anal canal
What are the boundaries of the ischiorectal fossae?
lateral wall: obturator internus and ischium
superomedial wall: levator ani and anal canal
base: skin of perineum
The anal canal is continuous with the ______. It is oriented an a ________ direction, due to the anterior pull of the _________. It terminates at the opening called the _______.
rectum
posteroinferior direction; pull of the puborectalis
opening called the anus
What are the muscle fibers of the external anal sphincter attached to?
anococcygeal ligament posteriorly
perineal body anteriorly
What innervates the external anal sphincter?
inferior rectal n, branch of the pudendal n
What role does the fat of the ischiorectal fossae play?
because the fossae are filled with fat, there are no vital organs in close proximity to the anal canal, therefore the canal is free to distend during defacation.
Where are the pudendal canals located?
What is contained within them?
located on the medial surface of obturator internus
pudendal n, internal pudendal a and v
What 3 structures pass from the pudendal canal to the anal canal, traveling through the ischiorectal fossae?
inferior rectal a, v, n
The UG triangle can be divided into what 2 spaces?
deep and superficial perineal spaces/pouches
The UG diaphragms spans what?
it is a sheet of MUSCLE that spans the gap between the ischiopubic rami
How does the UG diaphragm differ in F?
split in 2 halves by the vagina
What are the structures in the UG diaphragm (deep perineal pouch)?
1st part of urethra (F) or membranous urethra (M)
deep perineal muscles:
M: external urethral sphincter
both: deep transverse perineus
M: bulbourethral glands
What are the bulbourethral glands
- have ducts which empty into penil urethra
- during sexual excitement, they secrete a clear mucous which lubricates the urethra prior to ejaculation of semen
In females, what splits the superficial perineal space in half?
vestibule of the vagina
In a MALE, what are the contents of the superficial perineal space?
root of the penis
superficial transverse perineus muscle
body/shaft of penis
In a FEMALE, what are the contents of the superficial perineal space?
general: vulva or external genitalia, which includes…
labia majora
labia minora
clitoris
and deep to the skin:
bulbs of the vestibule
greater vestibular glands (Bartholin’s)
Superficial transverse perineus muscles
What 4 structures are in the root of the penis?
R and L crura
bulb of penis
ischiocavernosus m
bulbospongiosus m
Describe the location of the ischiocavernosus m
surround free surface of each crus
attach to ischiopubic rami
insert into corpora cavernosa
Which muscle is responsible for maintaining an erection, and how?
the ischiocavernosus m maintains an erection by compressing the veins that drain the corpora cavernosa
The corpora cavernosa is comprised of what?
erectile tissue
Describe the location of the bulbospngiosus muscle
arises from the perineal body and raphe of the penis
wraps around the bulb and posterior part of the corpus spongiosum
What muscle aids in emptying/compressing the urethra of urine and semen?
the bulbospongiosus
What fascia covers muscles in superficial perineal space?
deep perineal fascia
What muscle is located along the posterior border of the UG diaphragm?
superficial transverse perineus m
What are the 2 bodies of erectile tissue in the shaft of the penis? (One is bilateral)
And what covers these?
corpus spongiosum, bilateral corpora cavernosa
covered by Buck’s fascia
What forms the mons pubis?
Unified bilateral labia MAJORA
What surrounds the vaginal vestibule?
Labia minora
What are the structures in the labia minora?
vaginal vestibule, external urethral orifice, vaginal orifice, openings of the paraurethral glands and the greater vestibular glands
What are the 4 parts of the clitoris, and which is the only externally visible one?
2 crura
2 corpora cavernosa
1 body
glands clitoris, which is visible externally
Which part of the clitoris contains erectile tissue?
corpus carvernosum
What structure is continuous with the corpus cavernosum in F, and what surrounds the CC?
crus
ischiocavernosus muscle
During sexual arousal, which muscles contract and why, in FEMALES?
ischiocavernosus muscle, bulbocavernosus m
to retard the return of venous blood from the corpus cavernosum
What makes up the body of the clitoris
Unification of bilateral corpora cavernosa
What kind of tissue makes up the bulb of the vestibule?
erectile
What muscle covers the bulbs of the vestibule?
bulbocavernosus m
What is the function of Bartholin’s (greater vestibular) glands?
produce a clear mucous secretion during sexual arousal, lubricating the vulva
Arterial supply of the perineum is done by what vessels?
internal pudendal artery, external pudendal
internal = branch of internal iliac external = branch of femoral a
Describe the route of the internal pudendal a?
enters the perineum via the lesser sciatic foramen
enters pudendal canal
gives branches to anal canal and ischiorectal fossa, deep and superficial perineal space
Which branches of internal pudendal supply the erectile tissues and dorsal aa of the penis and clitoris?
helicine aa
The external pudendal a send deep and superficial branches to which 2 structures? (4 total: 2 for M, 2 for F)
M: scrotum and penis
F: labia majora and clitoris
What nerve supplies the same structures as the internal pudendal a? This is the main n supplying the perineum.
pudendal n (S2-4)
What are the 4 fiber types within the pudendal n?
- pregang PSNS (GVE) –> glands and sm muscle
- somatic motor fibers (GSE) –> skel muscle
- somatic sensory fibers (GSA)
- postgang SNS fibers (GVE) –> glands and sm muscle
The GSA (somatic sensory) fibers are associated with sensory receptors in what 3 structures?
pernieal skin
distal portion of anal canal, inferior to pectinate line
distal portion of vaginal canal
What perineal structures are drained by superficial inguinal LN?
superficial perineal space
distal portions of vagina and anus (below pectinate line)
What perineal structures are drained by internal iliac LN?
deep perineal space, proximal vagina, proximal anal canal (above pectinate line)
What is an episiotomy?
surgical incision in the area between the vagina and anus, during last stages of L&D to expand the opening of the vagina to prevent perineal tear
What structures are cut during an episiotomy?
posterior vaginal wall bulbocavernosus m superficial transverse perineus m skin subQ fascia
What is the order of 3 layers of sutures to repair episiotomy?
- vaginal wall
- muscle layer
- subQ fascia + skin
