Exam V: Nerves and Arteries Flashcards Preview

Anatomy > Exam V: Nerves and Arteries > Flashcards

Flashcards in Exam V: Nerves and Arteries Deck (33):

Sacral Plexus

Lumbosacral trunk: L4/L5
ONLY Ventral rami: S1-S4
Located anterior to piriformis
Exit sacral foramina
Obturator nerve: L2, L3, L4 (Lumbar plexus)


Sacral Plexus

Nerve: spinal cord segments
Pudendal: S2-4
Nerve to levator ani, coccygeus, external anal sphincter: S4
Nerve to piriformis: S2
Sciatic: L4-S3
Superior Gluteal: L4-S1
Inferior Gluteal: L5-S2
Pelvic Splanchnic: S2-4 (parasympathetic fibers from lateral horn)


Pudendal Nerve

S2, 3, 4
Supplies perineum
Exits greater sciatic foramen and enters perineum through lesser sciatic foramen
Travels in pudendal canal (obturator fascia)
Within canal branches


Pudendal: Deep Perineal Nerve

Perineal nerve – at UGD divides into superficial and deep branches

Deep perineal nerve: mainly muscular, transverse perinei (both), bulbospongiosus, ischiocavernosus

Supplies nerve to bulb that pierces bulbospongiosus and supplies corpus spongiosum and mucus membrane of urethrae


Pudendal: Superficial Perineal Nerve

Superficial perineal nerve:
medial and lateral branches
scrotal skin (labia majora)
posterior scrotal nerves,
enter and course through superficial space


Pudendal Nerve: Dorsal Nerve of Penis/Clitoris

runs along ischial and pubic rami within deep perineal space
branch to corpus cavernosum
pierces anterior fascia (of UGD)
runs between corpora cavernosa and pubic symphysis onto dorsum of penis (clitoris)
small branches distribute to glans penis (clitoris)
Does not supply skeletal muscle (unlike the inferior rectal and perineal nn.)


Pudendal Nerve Block

Ischial spine is the landmark via vaginal exam because pudendal nerve is along with sacrotuberous ligament
Inject in nerve before it branches off


Internal Iliac Branches

Anterior division:
Obturator (unless aberrant)
Uterine (female only)
Vaginal (F) / Vesicle (M)
Internal Pudendal
Inferior Gluteal
Middle Rectal

Posterior division:
Lateral sacral
Superior gluteal


Internal Iliac Posterior Trunk Branches

Iliolumbar: ascends out of pelvis and divides into iliac and lumbar branches

Lateral sacral: Course along posterior pelvic wall

Superior gluteal: Passes between lumbosacral trunk and S1 through GSF


Internal Iliac Anterior Trunk Branches

Umbilical artery usually 1st branch
Superior vesical
Inferior vesical: fundus of the bladder, prostate and seminal vesical (vaginal artery)
Middle rectal: rectum but also supplies the seminal vesicals and prostate
Obturator (variable)
Internal pudendal
Inferior gluteal passes between S1 and S2 or S2 and S3 (large)


Aberrant Obturator Branch

Aberrant Obturator artery when comes off something else other than anterior trunk of internal iliac

Comes off external iliac in this case, that goes over the pelvic rim into the obturator canal


Female Internal Genitalia Blood Supply

Uterine – arises from anterior trunk, runs on surface of levator ani toward uterine cervix between layers of broad ligament; crosses over ureter

Vaginal – directly from internal iliac or uterine artery; corresponds to inferior vesical artery (male) and supplies vagina, inferior region of bladder and pelvic part of urethra


Male Pelvic Organs Blood Supply

Superior vesicle to bladder
Inferior vesicle that supplies fundus f bladder, seminal vesciles, and prostate
Prostate – internal pudendal
Middle rectal - rectum


Pelvic Viscera Venous Drainage

Tributaries of internal iliac vein correspond to arteries.

Superior gluteal
Inferior gluteal
Internal pudendal
Lateral Sacral
Middle Rectal



Venous Draining of Penis

Superficial dorsal veins drain skin and prepuce of penis. Dump into superficial external pudendal vein.

Deep dorsal vein lies beneath Buck’s fascia, but superficial to tunica albuginea. Drains glans and corpora cavernosa via deep veins. Passes between two parts of suspensory ligament of penis and dumps into prostatic plexus


Pelvic Venous Plexus

Venous networks surround pelvic organs, anastomose with each other.

Pelvic venous plexuses are interconnected and drain into internal iliac vein, superior rectal to inferior mesenteric and to vertebral venous plexus (Batson’s plexus)

Connects to internal and external venous plexus – prostatic venous plexus; cancer cells can go to pre vertebral plexus and into the vertebral column (internal vertebral plexus?)
Also can carry to brain if goes higher up


Rectum Blood Supply

Superior rectal artery coming from IMA; portal system so can get portal hypertension in that area
Middle rectal from internal iliac and goes to caval system
Inferior rectal coming from internal pudendal and goes to caval system
*All anastomose with each other


Venous Drainage of Rectum: Hemorrhoids

When you have portal hypertension or cirrhosis the veins will dilate because the blood flow isn’t good
Internal rectal dilate = hemorrhoids
External rectal dilate from pregnancy and other pressures like constipation = hemorrhiods


Internal vs. External Hemorrhoids

Internal hemorrhoids:
Prolapse of anal mucosa which contain dilated veins from internal rectal venous plexus
Portal hypertension
Hepatic cirrhosis
Not painful because visceral innervation in this area

External hemorrhoids:
Blood clots in the external rectal venous plexus, covered by skin
Pregnancy, constipation


Anal Canal Blood Supply

Above pectinate line from superior and middle rectal, Below the pectinate line middle and inferior rectal artery


Ureter Blood Supply

renal, testicular, branches from the internal iliac and inferior vesical arteries


Bladder Blood Supply

superior, inferior vesical (uterine and vaginal in female)


Ductus Deferens Blood Supply

artery of the ductus deferens from the superior vesical artery


Seminal Vesicle Blood Supply

inferior vesical, middle rectal


Prostate Blood Supply

internal pudendal, inferior vesical and middle rectal arteries


Ovary Blood Supply

ovarian from aorta


Uterine Tube Blood Supply

uterine and ovarian vessels


Uterus Blood Supply

uterine and ovarian vessels


Vagina Blood Supply

vaginal artery (from uterine), inferior vesical and middle rectal


Male Urethra Blood Supply

urethral artery from internal pudendal


Female Urethra Blood Supply

inferior vesical and internal pudendal


Testes Blood Supply

testicular artery


Penis Blood Supply

internal pudendal