Perineum Flashcards
What are the boundaries of the perineum
inferior to pelvic diaphragm, bound by inferior pelvic aperture
What happens if you draw a line between the ischial tuberosities
You divide the perineum into the urogenital triangle, and anal triangle
What are the sischioanal fossae
fat filled spaces on either side of the anal canal that allow the anal canal to expand if necessary
What are the lateral walls of the fossae formed by
obturator internus and ischial tuberosity
What are the medial walls of the fossae formed by
External anal sphincter
What does each fossa project anteriorly into
The UG triangle, formin anterior recesses, allowing for easy spread of infection between UG and anal triangle
What is the importance of the ischioanal fossa communicating posteriorly
Allows for spread of infection between left and right sides of anal triangle
Where does the anal canal begin
At the anorectal flexure (held up by puborectalis)
What allows the anus to close off when not in use
anal columns and anal valves
What is the line where external tissue meets internal tissue in the anal canal
Pectinate line (inferior to anal valves
What supplies/drains anal canal superior to pectinate line
superior rectal vessels (IMA) with aid from middle rectal vessels
Where does lymph superior to pectinate line drain
internal iliac nodes
What innervation does superior to pectinate line receive
Parasympathetic and Sympathetic (similar to hindgut) Visceral sensory (stretch, ischemia)
What supplies/drains inferior to the pectinate line
inferior rectal vessels (to pudendal, to internal iliac)
Where does lymph drain inferior to the pectinate line
superficial inguinal nodes
What innervation does inferior to pectinate line receive
Somatic via inferior rectal nerve (pain, temp, touch)
What anastomoses happens in the anal canal
Superior rectal vein (proximal, portal) with Inferior rectal vein (distal, caval)
What are external hemorrhoids indicative of
portal hypertension
What is the internal anal sphincter made of
smooth muscle
What effect does innervation have on the internal anal sphincter
Sympathetic- stimulates contraction, prevents defecation
Parasympathetic- relaxes, allowing defecation
What is the external anal sphincter made of
Skeletal muscle, receiving somatic motor innervation
What does “potty training” involve
learning to control the external anal sphincter
What is SF fatty layer of SF perineal fascia continuous with
camper fascia
What is deep membranous layer of SF perineal fascia continuous with
Scarpa fascia (dartos fascia in men, colles fascia in women)
What separates superficial and deep muscles on the perineum (UG triangle)
Perineal membrane (openings for vagina and urethra)
What does the perineal membrane provide
attachment for erectile tissue and muscles of UG triangle
What is an episiotomy
incision made through, or lateral to the perineal body during child birth to minimize tearing
What are the external female genitalia
Mons pubis, labia majora, labia minora (prepuce), vestibule (hymen)
What is the erectile tissue in women
Corpora cavernosa (paired)- crus, body, and glans Bulbs of the vestibule
What muscles cover erectile tissue
Crura covered by ischiocavernosus
Bulbs covered by bulbospongiosus
What are the erectile tissues in men
Corpora cavernosa (paired)- crura Corpus spongiosum (unpaired)- glans, bulb
What covers the glans of the penis
The prepuce (foreskin)
What is the purpose of ischiocavernosus
aid in erection by compressing veins of corpora cavernosa and maintaining blood
What is the purpose of bulbospongiosus
aid in erection and expel semen during ejaculation
What muscle runs along the inferior border of the UG triangle
Superficial Transverse Perineal, helps stabilize perineal body
What are the deep perineal muscles
Deep transverse perineal (smooth and skeletal in females)
External urethral sphincter (surrounds membranous urethra in men)
What innervation does the external urethral sphincter receive
Somatic motor- stimulating contraction may help prevent urination
What are the levels of urethra in men
Prostatic, membranous, penile (spongy)
What are the glands of the female UG triangle
Bartholin glands (great vestibular), infection and cysts can occur open into vestibule, secrete mucus for lubrication
What are the glands of the male UG triangle
Bulbourethral (cowper) glands
empty into penile urethra
What spinal levels contribute to the sacral plexus
Ventral rami of L4-S4 Lumbosacral trunk (L4-L5) and ventral rami of S1-S4 go through piriformis
What levels contribute to the Pudendal nerve
S2-S4, keep your junk off the floor
What is the path of the pudendal nerve
Exits pelvic cavity through greater sciatic foramen, inferior to piriformis
Goes around ischial spine
Enters perineum through lesser sciatic foramen
Enters pudendal canal
What are the branches of the pudendal nerve after entering pudendal canal
Inferior rectal nerves
Perineal nerves
Dorsal nerve of penis or clitoris
What is a pudendal nerve block
used to anesthetize the perineum by directing the needle towards the ischial spine
What does parasympathetic do to sexual function
Helps achieve erection by closing off anastomoses to help blood pool in penis
How does Sympathetic innervation control sexual function
helps achieve emission by peristalsis of ductus deferens, and contracting internal urethral sphincter to prevent sperm back flow into bladder
What is the primary source of blood to the perineum
Internal pudendal artery
What are the branches of the internal pudendal artery
inferior rectal artery, perineal arteries, dorsal artery of the penis or clitoris, deep artery of the penis or clitoris
What do veins of perineum accompany
arteries of the perineum.
Except: superficial and dip dorsal veins of the penis
Where does lymph from SF perineum drain
superficial inguinal nodes
Where does lymph from deep perineum drain
internal iliac nodes
