hi let's talk about pelvic autonomics
in this video we'll discuss the basics of the autonomic supply to the pelvis so as you may
recall the the pelvic viscera are autonomically supplied by the inferior hypogastric plexus
which is a mixed autonomic plexus we can see the inferior hypogastric plexus here has a mesh work
of fibers that are highlighted green to represent both sympathetic and parasympathetic fibers
it's important to realize that that mesh work of fibers is going to extend over the viscera of the
pelvis as well so there's going to be a vesicle plexus associated with the bladder a uterovaginal
plexus associated with the uterus and vagina a rectal or middle rectal plexus associated with
the rectum and also a prostatic plexus associated with the prostate now let's take a look at some
of the inputs for the inferior hypogastric plexus or communications for the plexus
there are a couple of different sources let's let's keep the hypogastric nerves in our mind they
are cut here but what these are are condensations of both sympathetic and parasympathetic fibers
that are entering and leaving the pelvis and they communicate the superior hypogastric plexus
and the inferior hypogastric plexus so those hypogastric nerves really talk
between those two plexuses both in and out of the pelvis
now specifically within the pelvis there are going to be branches from ventral primary rami of s2
3 and 4. we can see the the vprs here are in yellow so there is s1
s2 s3 and s4 and coming off of s2 here we see this very nice blue branch that is a pelvic splanchnic
nerve coming off of s4 here we can see this blue branch which kind of runs by s3 and heads down to
the inferior hypogastric plexus these are the pelvic splanchnic nerves and i remember that
pelvic splanchnics are parasympathetics some of these fibers of the pelvic splanchnic nerves
can travel to the hindgut either through the superior hypogastric
plexus so by means of those hypogastric nerves or they can independently travel
up to the hindgut independently of those hypogastric nerves in terms of the sympathetic
inputs we need to look at the sacral sympathetic trunk which is highlighted in orange here
there are various ganglia of the trunk so there we can see the ganglion of one
and two and a slight one of three there and typically it's branches from the first
two ganglia here that are the sacral splanchnics but we actually have branches from s2 and s3 and
these are examples of sacral splanchnic nerves and i remember that as sacral splanchnic is sympathetic
so inputs hypogastric nerves mixed pelvic splanchnics parasympathetics sacral splenics
sympathetics in terms of the targets of these this plexus we'll have a vesicle plexus
serving the urinary bladder a prostatic plexus which would serve
if it were present here a prostate gland and it is not present here a uterovaginal
plexus serving the uterus and vagina and a rectal plexus serving the rectum and anal canal in terms
of the functions of this autonomic regulation they're rather straightforward so in terms of
parasympathetic stimuli we'll have contraction of the smooth muscle of the bladder and the rectum
um parasympathetics generally are vasodilators so the vasodilation as a result of parasympathetic
stimulation leads to tumescence so that's the engorgement of the erectile tissues and that
can further lead to erection there's also the initiation of glandular secretions so these are
stimulatory of glands as well the sympathetic responses so the uh the fight-or-flight response
visa constriction that's that's a very common sympathetic response the inhibition of rectal
or anal smooth muscle contraction um as well as the inhibition of bladder muscle contraction
um the initiation of emission so this is going to stimulate the secretion
of fluid from seminal vesicles into the urethra it's also going to
be stimulatory of the smooth muscle of the uterus and genital organs helping
to uh to produce ejaculation this is done in conjunction with somatomotor innervation
e.g from the pudendal nerve so sympathetics and somatic motor help to stimulate ejaculation
in terms of the general visceral afferent fibers recall there are two general types and
up until this point our discussions have been uh fairly straightforward so those gva fibers
that travel along with the parasympathetic fibers are are typically serving autonomic reflexes and
the general visceral efferent fibers that
travel with the sympathetics are serving visceral pain so this isn't the same thing as somatic pain
this is sensing uh distension uh stretching uh tearing um it's very poorly localized
um and generally referred to um to certain regions now there's something called the uh the pelvic
pain line and the uh the pelvic pain line corresponds with the inferior
margin of the peritoneum and so anything above the pelvic pain line general visceral afferent fibers
travel with sympathetics anything below the pelvic pain line those general visceral afferent fibers
travel with the parasympathetic fibers so that's that's something new for us um and referred pain
from visceral organs can refer to a variety of places but um generally um that referred pain is
more suprapubic in nature again but still very poorly localized so we've discussed the uh the
autonomics of the the pelvis and the various inputs to the inferior hypogastric plexus as
well as the various autonomic plexus targets of that inferior hypogastric plexus as well as the
the general visceral afferent fibers pathways this is your summary slide thank you for your