Anatomy IV - Perineum

popukudi's version from 2017-02-06 01:59


Question Answer
ant boundarypubic symphysis
post boundarytip of coccyx
lateral boundaryischial tuberosities, ischiopubic rami, sacrotuberous ligs
superior boundarypelvic diaphragm
UG triangleant to line traversing both ischial tuberosities; defined by ischial tuberosities, isciopubic rami, pubic symphysis; cont UG diaphragm, ext genitalia, terminal part of urinary tract
anal triangleposterior to line traversing both ischial tuberoisities; defined by coccyx, sacrotuberous lig, ischial tuberosities and cont anal canal, ischioanal fat pad, ischioanal fossa

Urogenital Triangle

Question Answer
deep pouchmuscular diaph (UGD) att laterally along ischiopubic rami, bridges aX full extent of UG-triangle; deep transverse perineal muscle lies superiorly to perineal membrane-->UGD
suspensionlat by isciopubic rami, anchored at midline at post border by perineal body, which is anchored to anal canal, suspended post by anal coccygeal lig to coccyx at midline
perineal membraneinf to deep transverse perineal m; made of tough aponeurotic sheet, which maint integrity of UGD
UGD fxnsclose off opening of UG hiatus; anchor membranous urethra and vagina; foundation for attachment of external genitalia
deep pouch ant boundarybody of pubis, lateral to symphysis
deep pouch lateral boundaryischiopubic rami up to ischial tuberosities
deep pouch post boundarytransverse line through ischial tuberosities through center attachment (perineal body)
deep pouch superior boundaryinvesting fascia (not cont) formed from fascia coverings from levator ani and obturator internus mm
deep pouch inferior boundaryperineal membrane
deep pouch contentsdeep transverse perineal m; compressor urethrae and spincter urethrovaginalis; membranous urethrae; bulbourethral glands; dorsal n. penis/clitoris; internal pudendal a.; dorsal and deep aa of penis/clitoris; internal pudendal vv
superficial pouchext genitalia and investing fascia; cont deep and superficial spaces
deep space of superficial pouch definitionb/w perineal membrane and deep perineal fascia
superficial space of superficial pouch definitionb/w deep perineal fascia and superficial perineal fascia
deep space components in male and femaledeep perineal fascia - cont w/external abdominal oblique and deep penile/clitoral fascia
deep space components in malecrus and bulb of penis; ischiocavernosus, bulbospongiosus, superficial transverse perineal mm.; deep perineal nerves; perineal aa
deep space components in femalecrus of clitoris; bulb of vestibule; greater vestibular gland; ischiocavernosus, bulbospongiosus, superficial transverse perineal mm; deep perineal nn; perineal aa
superficial space componentsfatty CT invested by superficial perineal fascia
superficial perineal fasciaatt to post margin of perineal memb and ischiopubic rami; reflects onto body of penis and clitoris, cont w/superficial fascial layers
superficial perineal fascia malecont SM fibers (dartos) that att to skin of scrotum and penis; lacks fatty tissue, cont w/Camper's and Scarpa's
superficial perineal fascia femaleno Dartos layer; both fatty and membranous fascia, which are cont with Camper's and Scarp'as fascia respectively

Male External Genitalia

Question Answer
scrotumdouble sac, sep by septum, houses testicles; outer layer of skin w/hair follicles and glands, inner layer of thickened fascia (superficial perineal) w/SM (Dartos)
scrotum fxnregulates temp by contracting (in response to cooling) or relaxing (in response to heat)
scrotum innsensory from ant scrotal (fr ilioinguinal), genital br of genitofemoral, post scrotal of pudendal, perineal of post fem cut
scrotum blood supplypost scrotal fr internal pudendal, ant scrotal fr ext pudendal, testicular (v. small contrib)
penis2 corpora cavernosa, 1 corpus spongiosum, firmly anchored to UGD; invested by mm and 2 layers of perineal fascia in UG-triangle, merge to form body
corpora cavernosumpaired cylinders of erectile tissue w/prox ends (crus) fused to UGD and ischiopubic rami; distal ends form 2/3 of penile body, terminate w/blunt ends capped by glans of penis
crusinvested by deep penile fascia and ischiocavernosus m, then deep perineal fascia (blends w/deep penile fascia on penis body) in UG triangle
corpus spongiosumsingle midline cylinder of erectile tissue; cont penile urethra; at prox end, att to perineal memb as penile bulb, which receives gland secs from bulbourethral glands and defines transition from memb urethra to penile urethra; att b/w CCs on inf surface-->body; invested by deep penile fascia from bulb to margin of glans corona
tunica albugineathick fibrous outer capsule over each erectile tissue
body of penispendulous, att to pubic symphysis by suspensory lig of penis, terminates as glans; at glans tip, urethra terminates as external urethral meatus
navicular fossadeep to ext urethral meatus, disrupts linear flow of urine to prod conc'd stream upon urination
perineal innmostly by pudendal n. (S2-4)
path of pudendal noriginates at sacral plexus, derived from ventral S2-4; exits out of pelvis via gtr sciatic foramen, enters perineum through lesser sciatic foramen, ant to sacrotuberous lig and post to sacrospinous lig (same as internal pudendal a); enters perineum in ischioanal fossa of anal triangal through pudendal canal
inferior rectal nsensory to anal canal; traverse ischioanal fat pad on way to rectum
distal brs of pudendalafter gives off inf rectal, goes along lateral perineum wall on surface of obturator internus; cont to post border of UGD, splitting to give rise to perineal and dorsal n of penis
perineal --> superficial perineal n and deep perineal nmotor to erectile tissue mm, superficial transverse perineal m, and mm in deep compartment (ext ur sphincter, deep transversus perineal m); superficial br terminates as post scrotal (or post labial), sensory to these
dorsal nenters deep pouch on sup surface of UGD, piercing sup perineal fascia, and runs along ischiopubic rami border, almost up to ant border of UGD; exists UGD by piercing perineal memb, runs along crus to dorsal body; travel b/w tunica albuginea and deep penile fascia to provide sensory to body and glans/clitoris
autonomic inputpelvic splanchnics (pregang parasymp S2-4) and symps from sacral splanchnics making up inferior hypogastric plexus; both sets converge-->cavernous nerves from inf hypogastric plexus, pierce pelvic and UGDs to inn erectile tissues
blood supply to penis/vaginainternal pudendal a (br of internal iliac in pelvis); follow same path as pudendal n in leaving pelvis and entering perineum; in perineum, gives off inf rectal br; internal pudendal then gives rise to perineal br, supplying strucs in superficial cmptmt; in deep cmptmt int pudendal gives off deep artery of penis/clitoris (supp CC) and dorsal a of penis/clitoris
blood supply to skin of penis and surrounding clitorisexternal pudendal a. from femoral a.
venous returninternal pudendal v. match a., return along same path into internal pudendal v except deep dorsal vein, which drains into prostatic/inferior vesical plexus; venous return of skin is via external pudendal v.

Female External Genitalia

Question Answer
mons pubisfatty elevation ant to pubic symphysis; underlying fatty layer of subcut tissue, covered w/pubic hair; post are labia majora and labia minora
labia majora2 symm folds providing protection for vaginal and urethral orifices; lined w/subcut fat, covered w/pubic hair and flank pudendal cleft; meet ant to form ant labial commissure; no joining posteriorly
labia minorapaired hairless folds of skin w/little subcut fat; flanks vestibule; join ant at base of clitoris ans ant frenulum AND post as post frenulum
clitorisformed by joining of CC; each forms a crus, which firmly attach to perineal memb and ischiopubic rami; CC invested by deep clitoral fascia (thinner than male counterpart); crus covered by ischiocavernous m, invested by deep perineal fascia; body mostly from CC; body and glans covered ant by prepuce
vestibular bulbfemale equiv of CS in male, but paired here; lateral to vaginal/urethra orifice at base of labia minora; firmly att to perineal memb, invested by thin layer of deep clitoral fascia; covered by bulbospongiosus m and invested by deep perineal fascia
greater vestibular glandsin base of labia minora, post to vestibular bulbs, lateral to vaginal opening; provide lube to vaginal opening upon sex stim; both give off short duct that opens lat to vaginal opening
ext urethra orificejust ant to vaginal orifice, cont by labia minora
innervationparallels male; supp by pudendal br into inf rectal, perineal, dorsal of clitoris; perineal-->superficial perineal-->posterior labial and deep perineal-->motor to erectile tissue in deep compartment
blood supply/returnparallels male w/internal pudendal a providing inf rectal, perineal, and dorsal a of clitoris

Anal Triangle

Question Answer
anal triangleregion post to transverse line b/w ischial tuberosities, flanked lat by sacrotuberous ligs and post by tip of coccyx
contentsischioanal fossa, anal canal, external anal sphincter, ischioanal fat pad, pudendal canal (allows psg of internal pudendal NAV from gluteal to perineum)
ischioanal fossacontains ischioanal fat pad, a fibrous/elastic fat mass that maint shape of region surr anal canal (and in ant recess, lat to birth canal in female); w/fat pad removed, fossa can be seen
ischioanal rooflevator ani (PD), encircling anal canal
ischioanal wallscoccyx, sacrotuberous lig, obturator internus m, ischiopubic rami
ant recessdirect comm w/ischioanal fossa; bounded inf by UGD, med by lev ani/PD, lat by obturator internus m/fascia and medial ischiopubic rami, ant by pubis body
ischioanal fossa contentspudendal canal
pudendal canalaccom entrance of pudendal n, n to obt internus and int pudendal a (exit of int pudendal v); med to point where obt int exits out of perineum through lesser foramen; obt has dense fascial covering, investing pudendal n and int pudendal vessels as enter via lesser foramen; pudendal n and all branches except inf rectal travel to UGD along surface of obt int, fully invested by obt internus fascia (must cut fascia to see them)
anal canalanchored at midline by anococcygeal lig (post to canal) and perineal body (ant to canal); puborectalis m and pelvic diaphragm also maint its position

Clinical Relevance

Question Answer
pudendal n blockfor childbirth/procedures in perineum; knowing anatomy of perineum w/respect to pudendal canal essential
episiotomyduring birthing, may be nec to surg enlarge canal to accom delivery; incision is made, preventing dmg to pubococcygeus m, either medially from post opening of vagina to ext anal sphinc or by med/lat incision from post wall of vagina twd ischiopubic rami
bad catheter1) select approp diameter, opening of ext urethral meatus has the narrowest D of all parts; 2) wall of memb urethra in deep pouch is v thin, easily torn away from penile/prostatic urethra; 3) penile urethra makes 80-90o sup bend in bulb of penis-must negotiate bend to avoid penetrating wall-->urine into perineum
bad catheter in membranous urethra w/o dmg to fascia surr sup aspecturine will not escape deep pouch
bad catheter with memb urethra torn at jxn of penile urethraurine will leak into superficial perineal pouch; if deep pouch fine, urine contained in deep space; BUT if deep fascia torn, urine can escape into superficial space of superficial cmptmt (cont w/superficial fascia of penis, Dartos, and ant abdomen wall; fused along post border of UGD and along lateral margins to ischiopubic rami (no leakage to legs or anal triangle)) - urine leak out of deep space to scrotum, around body of penis, and up ant abdomen wall