Perineum: External Genitalia and UG Triangle Flashcards
What muscles are found in the body of the penis
NONE
What composes the root of the penis?
Bulb and crura of penis and the muscles that cover them.
Where does the root of the penis attach?
In the superficial perineal pouch
Which part of the penis contains the external urethral orifice?
The glans of the penis
Describe the communication between the corpora cavernous penis
There is an incomplete separation between the two cavernous tissue to allow equal blood flow and thus a bilateral erectile state.
Is the corpus spongiosum found on the ventral or dorsal side
The ventral side.
What does the tunica albuginea of the penis surround?
The corpora cavernous and corpus spongiosum tissues.
What is found in the corpus spongiosum of the penis?
The spongy urethra.
Describe engorgement of blood flow in the corpus spongiosum
It does not become as engorged as the corpora cavernous in order to allow patency for passage of ejaculate.
What underlies the prepuce (foreskin)
corona and neck of glans penis
Frenulum of prepuce (penis)
median fold that passes from the deep layer of the prepuce to the urethral surface of the glans.
Does darts fascia cover the glans of the penis?
No.
Arterial supply to scrotum
Anterior scrotal arteries from terminal branches of external pudendal artery
Posterior scrotal arteries from branches of the perineal artery
Innervation of scrotum
Anterior scrotal nerves are branches from the ilioinguinal nerve and genital branch of genitofemoral nerve
Posterior scrotal nerves are branches of the superficial perineal nerve from the pudendal nerve and the perineal branch of the posterior cutaneous nerve of the thigh.
Contents of the spermatic cord
ductus deferens, testicular artery, artery to ductus deferens, testicular vein, internal spermatic plexus, genital branch of genitofemoral nerve, lymphatics
Where does the left testicular vein drain to
The left renal vein
Where does the right testicular vein drain to
the IVC
Where does the round ligament of the liver end
the labia majora
anterior labial commissure
location where the labia majora join anteriorly
posterior labial commissure
location where labia major joint posteriorly forming posterior extent of the vulva. Usually disappears after the first vaginal birth.
Frenulum of labia minor (fourchette)
location where labia minorus from each side meet in the midline posteriorly.
Frenulum of the clitoris
medial laminae of each labia minors unite in midline anteriorly.
Prepuce of clitoris
lateral laminae of each labia minors unite anterior to the glans of the clitoris
What type of tissue is the clitoris composed of?
Corpora cavernosa
Components of clitoris
Root and body
Where do 2 crura of clitoris attach
Ischiopubic rami
Where is the root of the clitoris found
superficial perineal pouch
What opens into the vestibule of the vagina
external urethral orifice and vaginal orifice, and openings of the greater and lesser vestibular glands.
Arterial supply to the vulva
anterior and posterior labial arteries
Innervation of the vulva
anterior and posterior labial arteries
Which vein lies just deep to the skin and darts fascia
superficial dorsal vein
Where does the superficial dorsal vein drain
The external pudendal veins or tributaries of the internal pudendal veins
Which vein lies deep to Bucks fascia
deep dorsal vein
Where does the deep dorsal vein drain
clitoris–> vesical venous plexus
penis–> prostatic venous plexus
What lies just lateral to the deep dorsal vein
The dorsal artery of the penis/clitoris
What lies lateral to the dorsal artery of the penis?
Dorsal nerve.
Vein that drains erectile bodies
deep dorsal vein
What type of fibers compose the dorsal nerve
Primarily somatic sensory fibers. May contain some postganglionic sympathetic fibers.
What covers the urogenital hiatus
urogenital triangle
What divides the superficial and deep pouch
perineal membrane
Layers of the UG triangle
skin, subcutaneous fascia-superficial fatty layer-Colles fascia, superficial perineal pouch, perineal membrane, deep perineal pouch, inferior surface of pelvic diaphragm
What is the superficial fatty layer of the superficial perineal fascia continuous with?
Camper’s fascia and ischioanal fat
Is the superficial fatty layer thicker in males or females
Females. It composes the labia majorus and mons pubis.
What is Colles’ fascia continuous with
Scarpa’s fascia in both males an females
Dartos fascia over penis and scrotum in males
Attachments of Colles fascia
attaches posteriorly to perineal membrane and perineal body. It does not extend into anal triangle. Laterally attaches to the ischiopubic rami and fuses with fascia lata of thigh.
Boundaries of superficial perineal pouch
perineal membrane and Colles fascia.
Contents of male superficial perineal pouch
Root of penis, crura of penis, ischiocavernous muscle, bulb of penis, bulbospongiousus muscle, perineal artery, superficial and deep perineal nerves, superficial transverse perineal muscles, deep investing perineal fascia.
Contents of female superficial perineal pouch
Vestibular bulbs, bulbospongiosus muscle, crura of clitoris, ischocavernous muscles, Bartholin glands, Skene’s glands, perineal artery, superficial and deep perineal nerves, superficial transverse perineal muscles, deep investing perineal fascia.
Where do the ducts of the Skene’s glands open
into the vestibule between the urethra and vagina.
Function of ischiocavernous muscle
maintain erect state by forcing blood from cavernous spaces within the crura into distal parts of corpora cavernous. Also compresses venous outflor of the penis/clitoris through the tributaries of the deep dorsal vein of the penis/clitoris.
Function of bulbospongiosus muscle
assist in erection by increasing the pressure on the erectile tissue and compressing venous drainage.
What perforates the perineal membrane
the urethra in males and females, the vagina in females.
Why does the perineal membrane have an anterior defect
To allow for drainage of the deep dorsal vein of the penis/clitoris into the pelvis and for accompanying cavernous nerves.
What converges at the perineal body
bulbospongiosus, external anal sphincter, superficial and deep transverse perineal muscles, external urethral sphincter, levator ani, and muscular portion of rectum.
Boundaries of deep perineal pouch
inferiorly the perineal membrane, laterally the fascia of obturator interns, and superiorly by inferior fascia of pelvic diaphragm.
Contents of deep perineal pouch
External urethral sphincter, deep transverse perineal muscles, bulbourethral glands (only in males), dorsal artery and nerve of penis/clitorsi
Bulbourethral glands
Ducts pierce the perineal membrane to drain into the spongy urethra. It secretes non-viscous material into the urethra before and during ejaculation to combine with sperm, seminal vesicle fluid and prostatic fluid to create semen.
4 parts of the male urethra
intramural or preprostatic urethra, prostatic urethra, intermediate urethra, spongy urethra
What artery supplies the inferior portion of the anal canal, anal sphincters, and perianal skin
Inferior rectal artery
What artery runs through the corpus spongiosum
artery to the bulb proximally, then the deep central artery of penis/clitoris.
Primary artery for erection
Deep artery of penis/clitoris
Terminal branches of deep artery of penis/clitoris
Helicine arteries
What artery pierces the perineal membrane and emerges on the dorsal surface of the penis or clitoris on either side of the deep dorsal vein
Dorsal artery of the penis/clitoris
Where does lymph of skin and subcutaneous tissue of perineum drain
superficial inguinal lymph nodes
Where does lymph of deep structures of perineum drain
deep inguinal nodes–> lumbar nodes?
What fibers are contained in the pudendal nerve
somatic sensory, somatic motor, postganglionic sympathetic fibers.
Branches of pudendal nerve
inferior rectal nerves, perineal nerve, dorsal nerve of penis
Branches of perineal nerve
Superficial perineal nerve and deep perineal nerve
Parasympathetic nerves of genitalis
Cavernous nerves.
