Pelvic Floor & Perineum Flashcards
Bony Pelvis Landmarks & Measurements
o True pelvis – deep to the pelvic inlet
o False pelvis – superior to pelvic inlet
o Conjugal (AP) Diameter – fixed distance; from sacral body to pubic symphysis (>11cm)
o Pelvic Outlet – distance between ischial spines (>10cm)
Pudendal Nerve & Clinical Correlation
-(ventral rami S2-S4) – passes behind ischial spine to enter perineum
o Supplies entire perineum (skin of external genitalia, muscles, and other areas)
o Clinical Correlation: Pudendal Block
Used for vaginal deliveries and minor surgeries of vagina and perineum
Injection where pudendal nerve crosses behind the ischial spine (palpable)
Transvaginal (more reliable & more common) or transcutaneous (perineal) approach
Variations in Male & Female Pelvis
Male (android pelvis) Thick and heavy Subpubic angle 90 degrees Pelvic inlet – rounded Pelvic outlet – large Ischial spines do not protrude inward
Pelvic Floor
(pelvic diaphragm, levator ani) – muscular diaphragm which supports pelvic viscera
o Puborectalis muscle – slight contraction responsible for right angle between rectum & anal canal
Relaxation of muscle when pooping gets rid of angle and allows poop to come out
o Sphincter of vagina – contracts during female orgasm
o Works with abdominal diaphragm to increase intra-abdominal pressure by raising pelvic floor
o Prevents downward displacement during coughs and forced expiration
Pelvic Floor Injury
o Muscles may be injured during childbirth
o Weakness of muscles may alter position of bladder neck or urethra urinary stress incontinence
(Kegel) exercise after childbirth who were leaking urine due to weakened muscles
Kegel muscles include pelvic floor muscles and other muscles of perineum
Pelvic Floor Take Home Message
o Differences between male & female are used in forensic medicine
o Pelvic factures common – often involve soft tissue injury
Anteroposterior compression in auto accidents
Falls may drive femoral head through floor of acetabulum
o Pregnancy – joints & ligaments relax (sex hormones, relaxin) ~15% increase in diameter
o Pelvic inlet & outlet may be barriers to normal delivery
o Conjugate (AP) diagonal (>11cm) is fixed distance at pelvic inlet which babies head must pass through in vaginal delivery; distance between ischial spines at pelvic outlet >10cm
o Sacroiliac ligaments are among strongest in body and the cause of lower back pain
o Pudendal block***
Perineum
– superficial to the perineal floor
o Diamond shaped space bound anteriorly by pubic symphysis, laterally by ischial tuberosity, and posteriorly b sacrum
o Imaginary line between ischial tuberosities divides perineum into 2 triangles
Urogenital – urogenital diaphragm with urethra and vaginal openings – located between the pubic bones
Anal – contains anal canal and 2 ischioanal fossas (allow anus to expand when pooping)
3 Layers in Perineum Below the Pelvic Floor Muscles
o Superficial fascia of Urogenital diaphragm
o Urogenital diaphragm and muscles including external urethral sphincter
o Inferior fascia of urogenital diaphragm (perineal membrane)
o Roots of external genitalia (penis and clitoris)
o Skin and superficial fascia
Roots of External Genitalia
Includes muscles
• Superficial transverse perineal muscle
• Ischiocavernosus – surrounds the crura
• Bulbospongiosus – surrounds the bulb
Includes erectile tissue – 2 crura (against pubic rami) & bulb fill with blood and harden
• Male – 2 crura and bulb come together to form penis
• Female – 2 crura come together to form clitoris; bulb NOT involved
Male Contents of Deep Pouch
(above perineal membrane between superior and inferior fascias of the urogenital diaphragm) – urogenital diaphragm (urethra sphincter muscles), membranous part of urethra, bulbourethral gland
Male Contents of Superficial Pouch
(below perineal membrane)– erectile structures that form penis (bulb and crura); proximal part of spongy urethra
Male Perineum Clinical Notes
o Urethral rupture can occur after blow to perineum; urine may flow into superficial perineal space
o Scrotum may be easily distended from a hernia or fluid production (orchitis) or bleeding
o Testes can be easily palpated due to thin wall of scrotum
o Palpation of testes and epididymis is important in the differential diagnosis between testicular cancer or inflammation of the epididymis
o Bulbourethral glands (cowper’s gland) – located between the 2 layers of urogenital diaphragm fascia, in the deep perineal pouch
Homologous to Bartholin’s (great vestibular) glands in female
Episiotomy
– surgical incision of perineum and posterior vaginal wall during labor
o Either median or mediolateral (avoids anal sphincter) incision
o Benefits – speeds up birth, prevents tearing, protects against incontinence, heals easier than tears
o Costs – infection, ↑ pain, longer healing times, increased discomfort when intercourse resumes
Female Contents of Deep Pouch
urogenital diaphragm (urethra sphincter muscle), urethra, vagina
Female Contents of Superficial Pouch
– erectile structures of clitoris (bulb/crura), Bartholin’s glands
Female Perineum Clinical Notes
o Perineal body is fibromuscular region between vaginal and anal canals; 8 muscles joint at PB
o Integrity of perineal body is important after childbirth; tearing may lead to prolapse of bladder, uterus, or vagina
o Perineal body also disrupted by trauma, inflammatory disease, and infection
o Numerous glands and ducts open onto surface making the area more prone to infections
o Bartholin’s glands (greater vestibular glands) in superficial perineal pouch
Bartholin’s cysts are more common in women aged 20-29; develops 2% of all women
Perineum Take Home Message
o Urogenital Diaphram suspends the roots of the penis and clitoris with clitoris lying below
o Perineal region is composed of 2 pouches: superficial and deep perineal pouches
Blood Supply & Ureter Location
o Aorta branches at L4 into common iliac and then external and internal iliac arteries o External iliac-becomes femoral artery in the thigh o Internal iliac Arteries Posterior division • Iliolumbar • Lateral sacral • Superior gluteal Anterior division • Vesicular – goes to bladdery • Umbilical • Superior vesicle • Inferior vesicle (vaginal) – goes to vagina • Middle rectal • Obturator • Internal pudendal • Inferior gluteal • Uterine o Ureter passes under the uterine artery (“water under the bridge”)
Lymph Drainage
o Testes and ovaries drain to aortic nodes because they receive bloody supply from aorta
o Organs supplies by common/external/internal iliac vessels drain to iliac nodes
o Superficial inguinal nodes in groin inferior to inguinal ligament
o Path: superficial inguinal nodes saphenous opening deep inguinal nodes femoral canal external iliac nodes common iliac nodes aortic nodes
Nerves of Sacral Plexus
Sacral Plexus – L4 to S4 o Lumbosacral trunk – L4 and L5 o Sciatic – L4-S4 o Posterior femoral cutaneous o Pudendal – S2 – S4
Bladder and Urethra (male) + Utero-vesicular pouch
o Anterior: pubic bone
o Superior: peritoneum and small intestine
o Posterior: rectum, vas deferens, and seminal vesicles
o Blood: internal iliac
o Lymph: internal iliac nodes
o Urethra = 8 inches long
Prostatic = 1 inch; receives 2 ejaculatory and 20 prostatic ducts
Membranous = 1 inch long and crosses urogenital diaphragm (external urethral sphincter)
Spongy = 6 inches long; part of it lies under the pubic bone and prone to injury
o Bladder – neck of bladder has involuntary internal sphincter that contracts during ejaculation to prevent retrograde ejaculation of semen into bladder
o Women – utero-vesicular pouch – fold in peritoneum that separates the uterus from the bladder
Foley Catheter
o Balloon at end of tip that will prevent urine from leaving bladder and force it into tube
o Male – more difficult to insert due to S shaped urethra
Suprapubic Cystotomy
– needle’s used to drain the bladder when flow is obstructed
o When bladder is full it rises up into abdomen
o Insert needle just superior to the pubic symphysis
o Needle travels through skin, linea alba, traversalus fascia, space of Retzius and the bladder
Clinical Notes: Bladder and Urethra
o Urethra & bladder infections more common in women: shorter urethra = more distensible
o Full bladder may extend up into anterior abdominal wall just above pubic bone; peritoneum is peeled off anterior body wall as bladder becomes intra-abdominal – no danger of peritonitis
o Transurethral resection of a bladder tumor is often performed using a cystoscope
o In transurethral resection of prostate (TURP), an instrument is inserted up the urethra to remove the section of prostate that is blocking urine flow
o Male urethra can be crushed against pubic bone; female rupture is rare because of short length
o Loss of bladder support in females by damage to perineal muscles during delivery is common; there could be herniation of the bladder into the vaginal wall (called cystocele)
