B8.044 Pelvic Vessels, Nerves, and Lymphatics Flashcards
general principles surrounding pelvic vasculature
most arteries of the pelvis are from the internal iliac arteries, but several are off the abdominal aorta
generally arteries and veins run together and have the same names
bifurcation of the AA
L4
same level as top of iliac crest
spinal taps performed here
pelvic arteries that come directly off of the AA
superior rectal artery (branch of IMA)
median sacral artery
ovarian and testicular arteries
testicular and ovarian venous return
L veins return blood to the L renal vein
R veins return blood to the IVC, lower pressure vessel
varicocele
incidence much more frequent on L side than R side
L renal vein is higher pressure than the IVC
renal vein entrapment syndrome
weight gain and sagging abdominal viscera can lead to compression of the L renal vein by the SMA
divisions of the internal iliac arteries
60% of the time: anterior and posterior
20% of the time: anterior, middle, posterior
10% of the time: different branch pattern
arteries from the posterior division of the internal iliac
superior gluteal
iliolumbar
lateral sacral
arteries from the anterior division of the internal iliac
obturator artery umbilical artery superior vesicular artery uterine artery vaginal artery inferior vesicular artery middle rectal artery
terminal branches of the internal iliac
inferior gluteal
internal pudendal
accessory obturator artery
present in 27% of people
branch off of external iliac artery w inferior epigastric
which arteries arise from the middle division of the internal iliac, when present
middle rectal artery
inferior gluteal artery
internal pudendal artery
arteries that serve the rectum
- superior rectal - off IMA
- middle rectal - off internal iliac
- inferior rectal - off internal pudendal (an internal iliac branch)
rectal venous return
- superior rectal vein - returns blood to the portal system
- middle rectal vein - returns blood to the IVC
- inferior rectal vein - returns blood to the IVC
venous plexus of the anus and inferior rectum
just underneath the mucosa
internal rectal plexus above the pectinate line, external rectal plexus in the perianal space
what causes hemorrhoids
increase in portal hypertension, lots of abdominal straining (with constipation), pregnancy, obesity, and other conditions can cause and engorgement of blood in either or both of the venous plexuses
external hemorrhoids
inferior to the pectinate line
painful
somatic innervation
internal hemorrhoids
superior to the pectinate line
painless
may go unnoticed for years unless they bleed or prolapse with defecation
first degree internal hemorrhoid
bulges into the anal canal during bowel movements
second degree hemorrhoid
bulges from the anus during bowel movements, then goes back inside by itself
third degree hemorrhoid
bulges from the anus during bowel movements and must be pushed back in with a finger
fourth degree hemorrhoid
protrudes from anus all the time
treatment for internal hemorrhoids
rubber band ligation
takes 7-10 days to necrose and fall off
collateral arterial circulation in the pelvis
branches from the aorta: ovarian artery IMA lumbar and vertebral arteries middle sacral artery
ovarian artery
anastomoses freely with uterine artery (thus serves both the ovaries and the fundus of the uterus)
also anastomoses with the vaginal artery
inferior mesenteric artery
forms superior rectal arteries which anastomose with the middle and inferior rectal arteries from the internal iliac and internal pudendal arteries
lumbar and vertebral arteries
anastomose with the iliolumbar artery
middle sacral artery
anastomoses with the lateral sacral artery
fibroid embolization
catheter placed through femoral artery and threaded into uterine artery
emboli used to disrupt blood flow to fibroid
only do this post-reproductive years
branches from the external iliac artery
deep iliac circumflex artery obturator artery (in 27%)
phleboliths
vein stones
arise due to calcification of the wall or thrombus of pelvic veins
epidemiology of phleboliths
rarely seen in developing countries
uncommon in children and more common in adults who consume a low fiber diet (about 50% of 60 year olds in US)
somatic pelvic nerves
sacral and coccygeal plexus
lumbosacral trunk
L4 and L5 ventral nerve rami combined
relationship between superior gluteal artery and pelvic nerves
generally leaves the pelvis by passing in between the lumbosacral trunk and S1 ventral ramus
relationship between inferior gluteal artery and pelvic nerves
passes out of the pelvis in between the S2 and S3 ventral rami
pudendal nerve
S2,3,4
distribution: external urethral and anal sphincters, motor and sensory to external genitalia
pudendal nerve mnemonic
S2,3,4 keep the poop, pee, penis off the floow
via pelvic splanchnic and cavernous nerves
sacral splanchnic nerves
postganglionic sympathetic nerve that leaves the sacral portion of the sympathetic chain
pelvic splanchnic nerves
parasympathetic
course of the sympathetic chain
travels down into the tip of the coccyx where the right and left chains join together at the ganglion impar
preganglionic sympathetic fibers no longer exit from the spinal cord below L1
postganglionic sympathetic axons continue to leave the sympathetic chain to join both dorsal and ventral rami at every spinal level since all spinal nerves need sympathetic innervation
course of the parasympathetic nervous system
preganglionic parasympathetic nerves have their cell bodies in the lateral column of the spinal cord at S2,3,4
travel down within the cauda equina to exit out of the ventral foramen of the sacrum at S2,3,4
innervation of the penis
dorsal nerve of the penis for sensation
autonomic innervation for vasodilation/ erection via prostatic plexus and cavernous nerves
erection
parasympathetic stimulation through the pelvic splanchnic, inferior hypogastric, and prostatic nerve plexuses + cavernous nerves
allows vasodilation of the helical arteries allowing more than 5-10 fold blood into the erectile tissue sinusoidal spaces
function of bulbospongiosus and ischiocavernous muscles
contract to help limit venous blood flow out of the erectile tissue and keep blood in the distal penis and out of the base of the penis
what is emission
delivery of sperm from the vas deferens, prostatic secretions and seminal secretions into the prostatic urethra
emission innervation
sympathetic innervation (L1,2 sacral splanchnic and inferior hypogastric nerves) to smooth muscle in walls of vas deferens, prostate, and seminal vesicle
ejaculation
forceful removal of semen from the urethra
internal urethral sphincter must remain closed
external urethral sphincter must open
bulbospongious muscles contract forcing semen from the penis base
internal urethral sphincter
smooth muscle
innervated by sympathetics
at junction of the bladder with the prostate
external urethral sphincter
skeletal muscle
at the pelvic diaphragm
innervation of bulbospongiosus
pudendal nerve S2,3,4
detumescence
loss of an erection
follows sympathetic discharge required for emission and causes constriction of the helical arteries reducing blood flow into the cavernous tissue
mixed autonomic plexuses of the pelvis
hypogastric plexuses
superior hypogastric plexus gives rise to L and R hypogastric nerve
L and R hypogastric nerves connect to R and L inferior hypogastric plexuses
inferior hypogastric plexuses
vesicle plexus
rectal plexus
prostatic plexus (males)
uterovaginal plexus (females)
support of the vaginal in the pelvis
middle 3rd: levator ani muscles, upper portion of the cardinal ligaments
cervical pain fibers
accompany parasympathetics from S2,3,4
fibers to the muscles and skin of the vulva
pudendal nerve and its branches
major function of perineal membrane
supports the urethra and maintains the urethrovesical junction
epidemiology of double/bifid ureter
1-4% of the population
how to distinguish the ureter from pelvic vessels during surgery
- identify peristalsis after stimulation by touching
2. identified Auberbach’s nerve plexuses which surround it
pudendal canal (Alcock’s canal)
thickening of the epimysium on the medial aspect of the obterator internus muscle
contains the pudendal nerve and internal pudendal artery and vein
use of pudendal nerve block
provide some relief from the pain of childbirth
injection of local anesthetic
how to administer a pudendal nerve block
pudendal nerve wraps around the ischial spine to gain access to the urogenital region
OB palpates ischial spine transvaginally and injects near this location
when can you not due a transvaginal pudendal nerve block
if baby’s head is too far down the birth
can be done transperineally
innervation of most of the female external genitalia
S3 dermatome
S4-S5 surround perineum and anus
first stage of birthing
dilation of cervix and distention of the lower uterine segment
visceral pain
mediated by T10-L1 segments of spine
second stage of birthing
distention of the pelvic floor, vagina, and perineum
somatic pain added
mediated by S2-S4 segments of spine
motor pathways to the uterus
leave spinal cord at T7-8
any sensory block below this can be used for analgesia during labor
lumbar epidural/lumbar spinal blocks
used for 1st stage of labor
injected into subarachnoid space
epidural
drug injected into extradural space, filled with venous blood and fat
drug travels via diffusion
caudal epidural block/ pudendal nerve block
used for 2nd stage of labor
pudendal nerve block vs. caudal epidural block
caudal is a “saddle block”
pudendal is the least invasive, good for those who want to “participate more in birthing process”
epidural meds
local anesthetics (bupivicaine, chloroprocaine, lidocaine) delivered in combo with opioids or narcotics (fentanyl and sufentanil)
when are epidurals placed
when cervix is dilated to 4-5 cm
in true active labor
spinal block vs epidural
spinal block similar but injected into subarachnoid space
faster effect than epidural
used if a C-section needs to be done, but its too late to start an epidural
how to find caudal epidural space
sacral hiatus
bottom line regarding lymphatic drainage of the pelvis
follows vebous drainage
anterior and middle pelvic organs at the level of the roof of the bladder drain into external iliac nodes
pelvic nodes highly interconnected, so drainage can pass in almost any direction
nodal evidence of inflamed hemorrhoids
enlarged superficial inguinal nodes
external vaginal lymphatic drainage
inferior vulva to superficial inguinal
rest to internal iliac (clitoris, labia minora, urethra)
testicular lymphatic drainage
lumbar aortic/ IVC nodes
prostate lymphatic drainage
internal iliac and sacral
seminal vesicle lymphatic drainage
internal and external iliac
