Pelvic Vasculature and Perineum Flashcards
Anterior Division of the Internal Iliac Artery
- Obturator Artery (can arise from inferior epigastric; important to remember when repairing hernia
- Umbilical Artery (gives off some superior vesical arteries; obliterated distal part =medial umbilical ligament)
- Inferior vesical artery
- Middle rectal artery
- (F) Vaginal and uterine artery (must ligate during hysterectomy)
- Inferior gluteal artery
- Internal pudendal artery
* Focus on where vessels are going as there is much variation
Uterine Artery
Passes OVER the ureter; must remember to ligate during ovariectomy
Internal Pudendal Artery
Travels out the greater sciatic foramen and back thru the lesser to supply perineal structures
*If it traveled thru the pelvic diaphragm, it could cause a potential site for herniation of pelvic organs
Posterior branches of Internal Illiac
- Iliolumbar artery
- Lateral sacral artery
- Superior gluteal artery
Inferior rectal nerve
Branch of the internal pudendal nerve that innervates the external anal sphincter and provides somatosensory to the bottom 1/2 of the anal canal
*Other branches of internal pudendal also include the dorsal nerve of the penis/clitoris and the scrotal/labial nerves
Beginning of anal canal
Coccyx
Internal Anal Sphincter
Parasympathetic stimulation for the splanchnic nerves causes relaxation of the sphincter
External anal sphincter
Somatic innervation from the pudendal nerve and contains three subgroups: 1. Deep part
2. Superficial part
3. Subcutaneous part
Anorectal ring
Composed of deep part of external anal sphincter, puborectalis, and internal anal sphincter
*Palpable during exam
Anal columns
Fold of mucosal membrane; contain the portal caval anastomoses
Anal valves
Epithelial folds indicating the site of the pectinate line
External hemorrhoids
Varicoses of the inferior rectal veins; very painful since lower half of anal column is somatosensory
Perianal abscess
Infection in the ischiorectal fossa that typically stems from torn anal valves or a fistula; can travel from side to side and anteriorly to affect urogenital structures
Urogenital Diaphragm
Lies inferior to the pelvic diaphragm and prevents herniation of prostate, uterus, and bladder thru the pelvic diaphragm
-Connected to inferior ramus and ischium
Deep perineal pouch
Consists of striated muscles (deep transverse perineal muscle and sphincter urethrae) and bulbourethral glands (M)
-Also contains the pudendal NAV
Deep transverse perineal muscle
Stabilizes the perineal body and reinforces the pelvic diaphragm
*Middle-layer muscle
Sphincter urethrae
Voluntary muscle that relaxes during microtuition; also fnxns during ejaculation
*Middle-layer muscle
Membranous urethrae
Found in the UGD; thinnest part of the urethra most susceptible to tearing, especially during catheterization
Bulbourethral glands
Found in the UGD; secretes lubricant during sexual arousal into the penile (spongy) area of the urethra
Superficial Perineal Pouch
Found inferior to the inferior fascial layer of the UGD and superior to the superior perineal fascia
Contains the superficial transverse perineal muscle, the erectile tissues (Crura and bulb), the internal pudendal NAV, and the bulbospongiosus and ischiocavernosus
Superficial perineal fascia
Colle’s Fascia-a continuation of Scarpa’s fascia; attaches posteriorly to the perineal body and laterally to the ischiopubic rami
*Continues in the scrotum as the Dartos muscle
Damage to perineum
Often causes urethral rupture @ the 90 degree angle where it enters the UGD
=>Urine enters superficial perineal pouch and anterior abdomen
- CANNOT enter ischiorectal Fossa or thigh due to posterior attachment of perineal membrane to UGD and lateral attachment of perineal membrane to the ischiopubic rami
- Can be caused by landing badly on top of fence
Muscles of superficial perineal pouch
- Superficial transverse perineal muscle
- Bulbospongiosus-aids the emptying of the urethra; compresses blood vessels during erection
- Ischiocavernosus muscles- aids in erection by compressing crus of penis
Root of penis
Composed of the crus and bulb of the penis; firmly attached to the inferior fascial layer of the perineal membrane
Suspensory ligament of penis
Originates at pubic symphysis and attaches to the tissue of the penis
Buck’s Fascia
Located deep to the superficial dorsal vein of the penis and envelops the deep dorsal veins and arteries of the penis
Tunica albuginea
White CT that invests the corpus cavernosa and forms a septum b/w the two
Dorsal artery of the penis
Supplies the skin of the penis and the surrounding erectile tissues
Penis lymphatics
Skin => Superficial inguinal nodes
Deep structures => Internal iliac nodes
Erection
Parasympathetics relax dorsal artery of the penis and artery of the bulb to engorge the penis w/ blood
*Veins are compressed by bulbospongiosus and ischiocavernosus
Ejaculation
Smooth muscle contraction of ductus deferens, seminal vesicle, and prostate gland to eject secretions; pudendal nerve activates bulbospongiosus
*Point and Shoot
Crura of clitoris
Paired erectile tissues that become the body of the clitoris anteriorly
Bulbs of vestibule
Split into two halves by the opening of the vagina; unite anteriorly as the glans clitoris
Greater Vestibular Glands
Analogous to bulbourethral glands; secrete lubricant
*Often become blocked and infected => cysts
Mons pubis
Mass anterior to the pubic symphysis covered w/ fat and hair
Frenulum
Point where the labia minora unites posteriorly
*Anterior point is the prepuce of the clitoris
Sensory innervation of the clitoris
Somatosensory nerves provided by dorsal nerve of the clitoris (from internal pudendal)
Episiotomy
Surgical incision into posterior wall of the vagina to prevent tearing of the perineal body during childbirth; surgical repair of this incision to the perineal body is much easier to repair
*Mediolateral incisions are more common because median incisions could damage the anorectal sphincter
Pudendal Nerve Block
Physician locates the ischial spine usually thru a transvaginal approach and injects anesthetic thru the vaginal wall and sacrospinous ligament to relax the pudendal nerve
*Performed to anesthetize the perineum prior to an episiotomy
Inferior rectal artery
Branch of the internal pudendal artery that supplies the lower 1/2 of the anal canal
Ischiorectal Fossa
Triangle formed by the skin, Obturator internus, and pelvic diaphragm
-Contains mostly fat but also the pudendal NAV bundle in the Obturator internus fascia and the external anal sphincter
Innervation of upper 1/2 of anal canal
Visceral sensory to the inferior hypogastric plexus
Crura of penis
Attached to perineal membrane and ischiopubic ramus
-erectile tissue
Navicular Fossa
Widening of the male urethra at the glans of the penis
Deep dorsal vein and vein to the bulb drainage
Prostatic venous plexus
