Perineum Flashcards
what are the main muscles of the perineum?
bulbospongiosus ischiocavernosus superficial transverse perineal deep transverse perineal external anal sphincter
what makes up the border in the perineum ?
ischial tuberosity
pubic symphysis
coccyx
what are the 2 triangles of the perineum?
anal triangle
urogenital triangle
what is the name of the fascia which stretches between right and left sides of the pubic arch?
deep perineal fascia
what is the innervation of the bulbospongiosus?
muscular branch of perineal nerve, branch of the pudendal nerve (S2-S4)
what is the function of the bulbospongiosus muscle?
supports and fixes perineal body/pelvic floor
compresses bulb of penis to expel last drops of urine and semen
assists in the erection of the clitoris
what is the innervation of the external anal sphincter?
branch of pudendal nerve (S2-S4)
what is the function of the external anal sphincter?
constricts anal canal during peristalsis and maintains continence
supports and fixes perineal bod/pelvic floor
what is the innervation of the ischiocavernosus muscle?
muscular branch of perineal nerve, branch of pudendal (S2-S4)
what is the function of the ischiocavernosus muscle?
maintains erection of the penis in males
what is the innervation of the superficial transverse perineal?
branch of pudendal nerve (S2-S4)
what is the function of the superficial transverse perineal?
support and fix perineal body to support abdomen-pelvic viscera and resist increased intra abdominal pressure
what is the innervation of the external urethral sphincter?
branch of pudendal nerve (S2-S4)
what is the function of the external urethral sphincter?
compresses urethra to maintain urinary continence
what is the perineal body?
fibromuscular structure located in the midline of the perineum
it is the final support of the perineum
what is the clinical significance of the perineal body?
central attachment of perineal muscles and functions to support pelvic floor
what muscles converge towards the perineal body?
bulbospongiosus
superficial transverse perineal
deep transverse perineal
external anal sphincter
what are the superficial and deep perineal pouches and what is their clinical significance?
fascial limited potential spaces transversed by the urethra
they may become infiltrated with urine following traumatic or surgical injury of the urethra
what is the external urethral sphincters innervation?
pudendal nerve S2-S4
what is the innervation of the internal urethral sphincter?
sympathetic T10-L2
is the external urethral sphincter located in the superficial or deep perineal pouches?
superficial perineal pouch
what muscle does the deep perineal pouch surround?
deep transverse perineal muscle
what are the 3 parts of the male urethra?
prostatic
membranous
penile/spongy
what is the tissue which surrounds the penile urethra called?
corpora cavernosa
what are the narrowest and widest parts of the male urethra?
narrowest - membranous as it passes through the external urethral sphincter
widest - penile
what is the major content of the ischio-anal fossae?
fat
why is the ischia-anal fossae often a site of abscess formation ?
often several fistulous tracks end in the fatty tissue
what are common causes of ischia-anal abscesses?
STI, crohns, blocked anal gland, infected anal canal
presentation is fullness and tenderness between anal tuberosity
through which foramen does the pudendal nerve pass through to reach the ischia-anal fossae?
lesser sciatic foramen
what vessels are present within the ischio-anal fossae?
pudendal nerve
obturator internus nerve
what structures does the pudendal nerve innervate?
muscles of the perineum
levitator ani muscles of the pelvic floor
what is the course of the internal pudendal artery?
branch of internal illiac
goes out through greater sciatic and around sacrospinous ligament then back in through the lesser sciatic foramen
what are the main branches of the internal iliac artery?
greater and lesser gluteal arteries
internal pudendal artery
obturator artery
what is the innervation of the external urethral sphincter?
somatic via pudendal nerve
what is the innervation of the internal urethral sphincter?
sympathetic - T10-L2 via hypogastric
parasympathetic - S2-S4 via pelvic nerves
what is the blood and nerve supply of the prostate and seminal vesicles?
sympathetic L1-L2 via hypogastric
superior and inferior vesical artery
what is the function of the puborectalis muscle?
maintains faecal continence by creating a U shaped sling aound the anorectum
what is the blood supply for the rectum?
above the pectinate line:
superior rectal artery (branch of inferior mesenteric artery)
below pectinate line:
inferior rectal artery (branch of the internal pudendal artery)
what is the neurovascucular supply of the rectum?
superior to the pectinate line: inferior hypogastric plexus
inferior to the pectinate line:
inferior anal nerves from the pudendal nerve
