Pelvis And Perineum Flashcards
Bony pelvis functions
. Supports and protects pelvic viscera
. Transmits upper body weight to lower extremities
. Provides stable base for lower limb function
. Forms birth canal
Bony pelvis structure
. R/L hipbones, sacrum, and coccyx
. Hipbone formed by ilium, ischium, and pubis that fuse in puberty
. Sacrum
. Coccyx
Joints of pelvis and descriptions
. Pubic symphysis: immobile, formed by fibrocartilage interpubic disc and R/L pubic bodies
. SI joints: R/L ilia and sacrum, reinforced by ant., post., an interosseous SI ligaments, minimal gliding and rotational movements
Pelvic ligament function
. Resist rotational forces generated when sacrum is loaded w/ weight ant. To its; axis. Of rotation
Pelvic ligaments
. Sacrotuberous: from sacrum to ischial tuberosity
. Sarcospinous: sacrum to ischial spine (deep to sacrotuberous)
. Ant., post., interosseous SI: make up SI joint
. Pubic: around pubic symphysis
Hip fracture vs pelvic fractures
. Hip: fracture of femoral head
. Pelvis: fracture of actual hipbone, have to worry about pelvic viscera damage
Relaxin
. Hormone released during pregnancy
. Relaxes pelvic ligaments and softens interpubic disc
. Inc. mobility in SI joints and pubic symphysis to facilitate childbirth
Superior pelvic aperture
. Pelvic inlet
. Pelvic brim formed by pubic crest, pecten pubis, arcuate line of ilium, sacral ala, and sacral promontory
. Boundary btw greater (false) pelvis (continuous sup. W/ abdominal cavity) and lesser (true) pelvis (contains pelvic viscera)
Inferior pelvic aperture
. Pelvic outlet/birth canal
. Delineated by ischial tuberosities, ischial spines, ischiopubic rami, and coccyx
. Diamond-shaped
. Correspond to perineum
. Male pelvis unique factors
. Robust w/ heavier rami
. Larger articular surfaces
. More pronounced muscle attachments
Adult female pelvis unique characteristics
. Ovoid pelvic inlet . Longer pubic rami . Wider spaced ischial tuberosities and ischial spines . Reduced sacral curvature . Greater subpubic angle . Wider greater sciatic notch
Interspinous distance
. Critical minimum dimension of birth canal
. Inlet widest transversely
. Outlet widest AP
. Allows fetal head and shoulders
Muscles of lateral wall of pelvis
. Obturator internus
. Piriformis
Obturator internus m. OIAN
. O: internal surfaces off bony boundaries of obturator foramen and obturator membrane
. I: tendon exits pelvis via lesser sciatic foramen to greater trochanter
. A:
. N: nerve to obturator internus (L5/S2)
Iscioanal fossa
. Obturator internus m. And obturator fascia form lat. wall
. Inf. To levator ani m.
Piriformis OIAN
. O: anterolateral surface of sacral body, sup. Margin of greater sciatic notch
. I: tendon exits pelvis via greater sciatic foramen to greater trochanter
. A:
. N: nerve to piriformis (S1-2)
Pelvis diaphragm/floor
. Funnel-shaped group of muscles that partially close off outlet
. Support abdominopelvic viscera esp. when intra-abdominal pressure inc.
. Consists of coccygeus and levator ani group muscles.
Coccygeus OIAN
O: ischial spine
I: pelvic surface of inf. Sacrum and coccyx
A: pulls coccyx ant. And supports pelvic viscera
N: branches of S4-5
Levator ani group
. Elevates pelvic floor to resist and/or raise intra-abdominal pressure
. Puborectalis, pubococcygeus, and iliococcygeus mm.
Levator ani group muscles innervation
. Nerve to levator ani (S3-4)
. Inf. Rectal nn. (S2-4)
. Coccygeal plexus (S4-Co1)
Puborectalis m. OI
O: body of pubis
. I: fibers go posteromedially to insert post. To anal canal on fiber from opposite side
. Some fibers merge w/ upper portion of external anal sphincter (and around vagina in women)
. Forms puborectal sling around anorectal junction to help maintain fecal continence
Pubococcygeus m. OI
. O: pubis and ant. Portion of tendinous arch of levator ani
. I: fibers go posteromedially to insert post. To anal canal on anococcygeal ligament and coccyx
Iliococcygeus m. OI
O: tendinous arch of levator ani
I: anococcygeal ligament and coccyx
Tendinous arch of levator ani
. Thickened portion of obturator internus fascia
. Extends in arch from pubis to ischial spine
. Gives origin parts of levator ani m.
Urogenital hiatus
. Midline space btw R/: puborectalis mm.
. Transmits urethra, vagina, and anal canal
Obturator canal
. Passage btw sup. Pubic ramus and sup. Margin of obturator membrane spanning obturator foramen
. Transmits obturator n./a./v.
Greater sciatic foramen and contents
. Formed by greater sciatic notch and sup. Border of sacrospinous and sacrotuberous ligaments
. Connects pelvic cavity w/ gluteal region
. Piriformis m. Exits pelvis here
. Sup. Gluteal n./a./v. (L4-S1) pass sup. To piriformis
. Inf. Gluteal n./a./v. (L5-S2), pudendal (S2-4) and internal pudendal a./v. Pass inf. To piriformis m.
Lesser sciatic foramen
. Formed by lesser sciatic notch and inf. Border of sacrospinous ligament and sup., border of sacrotuberous ligament
. Connects gluteal region w/ perineum
. Tendon of obturator internus m. Exits pelvis here
. Pudendal n. And internal pudendal a./v. Exit pelvis via greater sciatic foramen, pass lat. around ischial spine and sacrotuberous ligament, pass medially through lesser sciatic foramen to enter perineum
Perineum
. Diamond-shaped region located inf. To pelvic diaphragm and btw prox. Thighs
. Includes external genitalia, openings of urinary, GI, and reproductive tracts, assoc. muscles, and neurovasculature
Boundaries of perineum
. Ant.: pubic symphysis . Anterolateral: ischiopubic rami . Lat.: ischial tuberosities . Posteroateral: sacrotuberous ligaments . Post.: inf. Sacrum and coccyx
Transverse line connecting ischial tuberosities divides perineum into _____
. Ant. Urogenital (UG) triangle
. Post. Anal triangle
What does anal triangle contain?
. Anal canal
. Anal orifice
. R/L ischioanal fossae
External anal sphincter
. Skeletal muscle fibers circle inf. End of anal canal
. Superficial fibers attach to perineal body and coccyx
. Deep upper fibers blend w/ puborectalis m.
. Closes anal orifice to prevent defecation
External anal sphincter innervation
. Inf. Rectal nn. (Branches of pudendal nn.)
Ischioanal fossae
. Wedge shaped, fat-filled lat. to anus
. Inf. Boundary: perianal skin
. Lat.: obturator fascia covering obturator internus mm.
. Sup.: Inf. Surface of levator ani m. Covered by deep fascia
. Med.: walls of anal canal
. Post.: sacrotuberous ligament
. Ant.: ant. Recesses of ischioanal fossae extending to UG triangle
Anterior recesses of ischioanal fossae
. Extend to UG triangle
. Sup. To muscles of deep perineal pouch
. Pyramid shaped
. Apex is closed, points ant. Toward pubis
. Base is open and continuous post. W/ ischioanal fossae
. L/R fossae communicate deep to anococcygeal ligament in deep post-anal space
. Permits movement of pelvic diaphragm and expansion of anal canal
Pudendal canal
. In lat. wall of ischioanal fossa w/in obturator internus m. Fascia
. Transmits pudendal n. And internal pudendal a./v. And branches that supply perianal structures
Superficial perineal fascia components
. SubQ of perineum
. Fatty layer
. Membraneous layer
Fatty layer of superficial perineal fascia
. Continuous w Camper’s fascia
. Forms labia majora and mons pubis in females
. Minimal/absent in scrotum/penis in males
Membraneous layer of superficial perineal fascia
. Colles fascia
. Continuous w/ dartos fascia
. Attaches lat. to ischiopubic rami and fuses post. Perineal body and post. Border of perineal membrane
. Fuses w/ deep fascia of thigh (fascia lata) at inguinal ligament
Deep perineal fascia
. Investing fascia of muscles of superficial perineal pouch
. Attaches lat. to ischiopubic rami
. Ant. Continuous w/ deep fascia of external oblique and rectus sheath
Perineal membrane
. Tough investing fascia of the muscles of deep perineal pouch
. Attaches lat. to ischiopubic rami and partially spans UG triangle
. Divides the UG region from inf. Surface of pelvic diaphragm (sup.) to the Colles fascia into 2 stacked fascial pouches
Superficial perineal pouch
. Enclosed compartment
. Potential space located btw Colles fascia (inf) and perineal membrane (sup)
. Laterally bounded by ischiopubic rami
. Post. Bounded by fusion of Colles fascia and post. Margin of perineal membrane
. Contains erectile tissues, superficial perineal muscles, nn. Vessels, portion of urethra (males and females), vagina and greater vestibular glands in females
Deep perineal pouch
. Loosely defined
. Btw perineal membrane (inf), inf. Fascia of pelvic diaphragm (sup) and obturator internus fascia (lat)
. Contains deep perineal mm., dorsal neurovasculature of penis/clit, portions of urethra, bulbourethral glands in males, and ant. Recesses of ischioanal fossae
Perineal body
. Musculofibrous mass in median plane btw anal canal and vestibule of vagina or bulb of penis
. Fuses to post. Border of perineal membrane and sup. W/ rectovesical/rectovaginal septum
. Site of convergence of several perineal mm.
. Maintains integrity of pelvic floor and fecal incontinence
Muscles that converge in perineal body
. Bulbospongiosus m.
. Superficial and deep transverse perineal mm.
. External anal sphincter m.
. Fibers from external urethral sphincter m.
. Levator ani
. Smooth muscle fibers from rectum
What happens if there is disruption of perineal body?
. Pelvic floor laxity
. Weakening of urethral and anal sphincters
. Herniation or prolapse of pelvic viscera (bladder, uterus, vagina, and/or rectum)
Penis components and descriptions
. Shaft: corpus spongiosum (ventral midline tube w/ urethra) and paired corpora cavernosa lined w/ endothelium forming sinuses btw tubes
. Glans of penis: terminal expansion of corpora spongiosum (distal urethra and external urethral orifice)
. Corona of glans: projection of glans beyond corpus spongiosum
. Prepuce (foreskin): hood of kin and fascia. Sheathing glans, attached ventrally by frenulum of perpuce
Coverings of penis from superficial to deep
. Skin
. Superficial dartos fascia
. Deep (Buck) fascia
. Tunica albuginea covering each of the erectile bodies
Components of vulva
. Mons pubis . Labia majora . Labia minora . Clit . Vestibule
Mons pubis
. SubQ fat pad superficial to pubic symphysis
Labia majora
. Paired fatty skin folds lat. to labia minora
Labia minora
. Paired folds of skin and fat-free fascia med. to majora
. Unite ant. To form dorsal perpuce and ventral frenulum of Clit
. Unite post. To vestibule at frenulum of labia majora
Clit
. Has body and glans
. Fused corpora cavernosa
. Dorsal and ventral surfaces of clit same as penis
. Thinner fascial layers than penis
Vestibule in vulva
. Area btw labia minora
. Contains external urethral orifice, vaginal orifice, and openings of ducts of greater vestibular (Bartholin) glands
Root of penis
Formed by erectile bodies (corpora cavernosa, corpus spongiosum) proximally
Crura of penis
. Prox. Portions of corpora cavernosa that attach to ischiopubic rami
. R/L crura fuse at pubic symphysis
Bulb of penis
. Broad proximal portion of corpus spongiosum
. Attaches to inf. Surface of perineal membrane
. Urethra pierces sup. Surface of bulb and turns ant. To becomes spongy urethra
Membraneous urethra
Part of male urethra within deep perineal space
Spongy urethra
. Traverses superficial perineal pouch w/in penis bulb
. Continues distally through penis body w/in corpus spongiosum
What forms root of clit?
. Proximal
. 2 crura
Crura of clit
. Proximal portions fo corpora cavernosa
. Attach to ischiopubic rami
. R/L crura unite to form body and glans of clit at pubic symphysis
Bulbs of vestibule in vulva
. 2, pear-shaped erectile bodies
. Lat. to vestibule and vaginal opening
. Attach to inf. Surface of perineal membrane
. Constrict vaginal. Orifice when engorged
Superficial perineal mm.
. Innervated by branches of deep perineal n.
. Bulbospongiosus mm.
. Ischiocavernosus m.
. Superficial transverse perineal m.
Bulbospongiosus mm. OIA In males
. Paired muscles that envelope bulb of penis
O: perineal body and midline raphe of ventral surface of bulb
I: perineal membrane and fascia of corpora spongiosum and cavernosa
A: aid in expulsion of semen/urine, help maintain erection by restricting vv.
Bulbospongiosus mm. OIA In females
. Paired mm. That envelope ipsilateral bulb of vestibule and greater vestibular gland
O: perineal body
I: pubic arch, fascia fo body of clit
A: assist in clit erection, compress greater vestibular glands and constrict vaginal opening
Ischocavernosus m. OIA
. Paired muscles enveloping crura
O: ischiopubic ramus
I: crura and perineal membrane
A: maintains erection by compressing crura and restricting vv.
Superficial transverse perineal m. OIA
. Paired mm. That course parallel and superficial to post. Border of perineal membrane
O: ischiopubic rami and ischial tuberosities
I: perineal body
A: stabilize pelvic floor and perineal body
Greater vestibular glands
. Mucus-excreting glands lat. to vaginal vestibule
. At post. Ends of vestibular bulbs
. Provides lubrication to vaginal orifice
Episiotomy
. Enlarges vaginal orifice
. Incision through perineal skin and mm. Through post. Vaginal wall
Perineal lacerations
. Occur during childbirth
. Can damage perineal body and external anal sphincter
Bartholin cyst
. Ducts of greater vestibular glands may become obstructed
. Cause fluid swelling
. Small cysts resolve on their own
. Larger cysts are drained
Extravasation of urine
. Injury ruptures spongy urethra and tear Buck fascia
. Passage of urine into superficial perineal pouch
. Blood/urine may accumulate around penis or lower abdominal wall deep to scarpa’s fascia
. Usually looks butterfly shaped around penis
. Won’t pass into thighs because Colles fascia fuses to fascia lata
. Fluid can’t pass into anal triangle because Colles fascia fuses w/ post. Edge of perineal membrane
Deep perineal mm.
. Innervated by deep perineal mm.
. Deep transverse perineal mm.
. External urethral sphincter m.
Deep transverse perineal mm. OIA
. Paired mm. That course parallel and deep to post. Border of perineal membrane
O: ischiopubic rami and ischial tuberosity
I: perineal body and external anal sphincter
A: stabilize pelvic floor and perineal body
External urethral sphincter m. In males
. Voluntary sphincter composed of striated m.
. Inf. Fibers encircle membraneous urethra and attach to ischiopubic rami (also called compressor urethrae m.)
. sup. Fibers extend sup. To neck of bladder spanning ant. Prostate gland and prostatic urethra
External urethral sphincter m. In females
. Compound urogenital sphincter w/ Several components
. Upper fibers encircle proximal urethra forming external urethral sphincter proper
. Lower fibers encircle urethra and vagina (sphincter urethrovaginalis) and anchor the urethra to ischiopubic rami (compressor urethrae m.)
Bulbourethral (Cowper’s) glands
. Produce pre-cum
. Lat. to membranous urethra w/in deep perineal pouch
. Ducts penetrate perineal membrane and bulb to empty into spongy urethra
Anterior recesses of ischioanal fossae
. Bilateral projections of ischioanal fat into UG triangle sup. To perineal membrane and post. UG diaphragm
Pathway of pudendal n. And internal pudendal n. To reach perineum
. Exit pelvis via greater sciatic foramen and course lat. to ischial spine and sacrospinous ligament
. Turn med. through lesser sciatic foramen to enter pudendal canal w/in lat. wall of ischioanal fossa
. Courses ant. W/in canal giving off branches that pierce fascial walls of canal to reach targets
Pudendal nerve
. S2-4
. Provide motor and sensory innervation to perineal structures
Inferior rectal (anal) n.
. Crosses ischioanal fossa to arch anal canal
. Motor innervation to external anal sphincter and levator ani m.
. Sensory from perianal skin and anal canal inf. To pectinate line
Inferior rectal n. Damage causes ____
Damage results in loss of sensation in anal orifice and fecal incontinence
Perineal n.
. Supplies structures w/in superficial and deep perineal pouches
. Superficial perineal n. Gives rise to post. Scrotal/labial nn. Innervation skin of central perineum
. Deep perineal n. Innervates all skeletal muscles of UG triangle, provide sensory to vaginal vestibule, lower vagina, and urethra
Dorsal n. Of penis/clit
. Sensory from distal penis/clit
. Courses ant. W/in deep perineal pouch sup. To perineal membrane
. Accompanied by internal pudendal a. Then by terminal branch (dorsal a. Of penis/clit)
. Pierces perineal membrane and courses ant. On dorsal surface of body of penis/clit
Anterior scrotal/Labial nn.
. Branches of ilioinguinal nn. And genital branch of genitofemoral nn.
. Convey sensory from ant. Scrotum/vulva
Perineal branch of post. Femoral cutaneous n.
. Supplies skin of posterolateral perineum
Internal pudendal artery
. Main blood supply of perineum
. From internal iliac a. (Ant. Division) and courses w. Pudendal m.
. Passes sup. To perineal membrane, causes ant. W/in deep perineal pouch
. Terminates by dividing into deep and dorsal aa. Of penis/clit
. W/in deep pouch it accompanies dorsal n. Of penis/clit
Branches of internal pudendal artery
. Inf. Rectal a. . Perineal a. . Artery to bulb of penis/vestibule (pierces perineal membrane to enter bulb) . Deep a. Of penis/clit . Dorsal a. Of penis/clit
Inf. Rectal artery
. Supplies external anal sphincter
. Mucosa of anal canal inf. To pectinate line
. Skin of anal triangle
Perineal artery
. Gives off muscular branches then terminate as post. Scrotal/labial aa.
Deep artery of penis/ clit
. Enters crus of corpus cavernosum
. Continues into body of penis/clit
Dorsal artery of penis/clit
. Main arterial supply to distal penis/clit
. Courses ant. On dorsal surface of corpus cavernosum btw tunica albuginea and deep penile/clitoral fascia
. Medal to dorsal n. And lat. to deep dorsal vein
External pudendal artery
. Arises Rome emoral a. In femoral triangle
. Supplies body wall structures of ant. Urogenital region
Venous drainage of perineum
. Internal pudendal v.
. Deep dorsal v. Of penis/clit
. Superficial dorsal v. Of penis/clit
Internal pudendal v. And branches
. Drains most of perineum to internal iliac v.
. Tributaries follow course of internal pudendal a. And branches
. Inf. Rectal v.: drains internal rectal venous plexus inf. To pectinate lines and perianal skin
. Perineal v: receives post. Scrotal/labial vv. And other venae comitantes of internal pudendal a. Branches
Deep dorsal v. Of. Penis/clit
. Unpaired vessel draining cavernous spaces of erectile tissues
. Courses inf. To pubic symphysis and drains to prostatic (male) or vesicular (female) venous plexus
. Drains into internal iliac v.
Superficial dorsal v. Of penis/clit
. Paired vessels (R/L)
. Drain into external pudendal vv.
. Btw superficial and deep fascia of penis/clit
. Courses in plane btw superficial fascia (dartos in males) and. Deep fascia of penis/clit
Order of neurovasculature of penis/clit from superficial to deep
. Right dorsal n. . Right dorsal a. . Deep dorsal v. . Right dorsal a. . Right dorsal n.
Lymphatic drainage of perineum in male
. Lymph from scrotum and skin of penis drains to superficial inguinal lymph nodes
. Glans and distal urethra drain to deep inguinal lymph nodes
. Erectile bodies and prox. Urethra drain to internal iliac nodes w/in pelvis
Lymphatic drainage of perineum in females
. Lymph drains to superficial and deep inguinal lymph nodes in femoral triangle
. Urethra, gland of clit, and ant. Labia minora drain to internal iliac nodes w/in pelvis
Innervation coordinating erection
. Parasympathetic dilates penis/clit aa. And relaxes smooth muscle in venous sinuses of erectile bodies
. Blood flows into sinusoids producing erection
. Pressure from inc. blood volume produces spinal reflex (via. Pudendal n.) that causes reflexive contractions of bulbospongiosus and ischiocavernosus mm. (Impede venous drainage)
Innervation coordination of emission
. Sympathetic causes peristalsis of reproductive ducts and accessory sex glands
. Seminal fluid (male) or vaginal and glandular secretions (female) release
Innervation coordination of ejaculation
. Sympathetic constricts internal urethral sphincter m.
. Spinal reflex (via pudendal n.) produces rhythmic contractions of somatic pelvic mm.
. Rhythmic contractions of bulbospongiosus m. Propel semen through urethra
Innervation coordination of remission
. Sympathetic produces vasoconstriction
. Relaxes bulbospongiosus and ischiocavernosus mm.
. Allows blood to drain from erectile tissues
Obturator fascia
. Invests pelvic and perineal surfaces of obturator internus m.
Tendinous arch (Argus tendineus) of pelvic fascia
. Fascial bands running from pubis to sacrum bilaterally
. Flanks viscera where they penetrate pelvic floor
