hi let's talk about the renal vasculature in this video we'll discuss the flow of blood to
and through the kidneys will also discuss left renal vein entrapment syndrome and discuss the
relationships of the vessels that may contribute to the susceptibility so the kidney is divided
into several renal segments each segment is supplied by its very own segmental artery so
typically what we see is the renal artery dividing into 1 2 3 4 5 segmental arteries these segmental
arteries are End arteries which means that they do not anastomosis with one another therefore
the segments that they supply with blood are standalone elements they can be surgically
removed or resected in a partial nephrectomy without jeopardizing the parenchymal of the
other segments now these segments include an apical sometimes called the superior segment
as well as an inferior segment there is also anterior superior segments and anterior inferior
segments and if you can imagine this segmental arteries segment it will be a posterior segment
that basically overlaps with the anterior superior and anterior inferior segments so those are the
five segments even though the segmental arteries and their branches don't anastomosis some of the
the inter renal veins will typically anastomosis with one another now let's take a look at how we
might subdivide a segment and I think that this is going to help reciprocally illuminate the names
of some of the vasculature so within a segment we can have lobes and a lobe is going to be a single
renal pyramid plus all of the cortex immediately surrounding it so about half of a column all of
the cortical arch and all of the other columns that would surround it so that's a lobe lobes can
be further subdivided into lobules and a lobule is a little bit of that cortical arch there between
these cortical radiate arteries that's going to surround a single medullary array we'll get into
the histology of that but that is a lobule and those arteries that define a lobule are cortical
radiate arteries and by various people they may be referred to as interlobular arteries
now let's take a look at the branching pattern here so this begins with the renal artery renal
artery divides into 1 2 3 4 5 segmental arteries the segmental arteries are going to divide into
interlobar arteries so there's an interloper artery there's an interloper artery these
interloper arteries ride the margins between the medulla and the renal columns and they round the
bend of the pyramid and on the base of the pyramid they turn into arcuate arteries so
segmental to inter low bar to arcuate arteries coming off both the interlobar arteries and the
arcuate arteries are the cortical radiate or interlobular arteries so these cortical radiate
arteries can pierce into the cortex either in the column or in the arch they radiate out into the
cortex that's why they're called cortical radiate arteries a fantastic name for them these cortical
radiate arteries are going to give rise to several afferent arterioles the afferent arterioles feed
into specialized capillary beds called glomeruli this is where the glomerular filtration occurs a
glomerulus is then going to feed into an efferent arteriole so a farad arterioles
arrive at the glomerulus efferent arterioles exit the glomerulus and the efferent arterioles are
going to supply peritubular capillaries as well as elaborations of peritubular capillaries called
Vasa recta which translate into straight vessels these are going to be associated with nephron
loops of juxtamedullary nephrons peritubular capillaries feed into peritubular venules which
then feed into cortical radiate veins which then feed into arcuate veins into interlobar veins
and into renal veins what I care about most is that you understand the branching pattern of the
arteries through to the peritubular capillaries and vasa recta so renal arteries into segmentals
and to interlobars into arcuate arteries into interlobar into arcuate arteries both
in two cortical radiate arteries then into eighth arterials then into glomeruli then into efferent
arterioles then into peritubular capillaries into vasa recta now if you're keeping score
here from your your knowledge of vasculature you might see that we have a capillary bed
then feeding into another capillary bed by means of an intermediate vessel whenever we have that
it's called a portal system and we call these the renal portal systems and they are arterial
portal systems because efferent arterioles connect these capillary beds now let's take
a look at these cartoons of cortical and inject stew medullary nephrons and their blood supply
so here's the medulla there's the cortex here's an arcuate artery coming along and supplying blood up
through a cortical radiate artery here are the afferent arterioles into the glomerular making
that filtrate coming off of that is going to be the efferent arterioles efferent arterioles give
rise to the peritubular capillaries we need these peritubular capillaries so that we can
have tubular secretion and reabsorption on ejecta medullary nephron we also have these vasa recta or
these straight vessels that dive down deep with that elongated nephron loop to pull water out
of the medulla to maintain that hyper osmotic gradient that allows water to continually flow
chasing sodium out of that nephron loop now on a grossly visible level you're not going to see all
of these things if you have a microscope fantastic you'd be able to visualize everything but in the
lab you're only going to be able to gets to about the level of the arcuate artery and even there
you really have to get lucky to find one that's sectioned right so let's let's take a look at
what we can see here there's a renal artery here we can see a segmental artery there is
another segmental artery sometimes we may have accessory renal arteries these aren't all that
uncommon about one in every three kidneys will have an accessory renal artery they may either be
hilar meaning they enter the hilum of the kidney or they may be polar entering either the superior
or inferior poles these segmental arteries they divide into interlobar arteries as you recall
and if we follow this interlobar artery around the base we can see it turning into an arcuate
artery anything beyond the arcuate artery you'd probably need latex injected vasculature and or
some sort of hand lens to see the the cortical radiate arteries and a microscope to see beyond
that now let's discuss some of the grossly visible veins here because this is a fascinating story so
one very prominent vein of the abdomen here is the inferior vena cava right the inferior vena cavas
going to receive blood from the lower limbs and pelvis some of the the abdominal viscera directly
some of it indirectly after it's gone through the renal I'm sorry that paddock portal system
on the other end of the liver will also receive blood from the the body wall in terms of the
kidneys the kidneys drain directly into the cable system here via right and left renal veins and
what you can see is that the left renal vein is exceedingly longer than the right renal vein and
that left renal vein also has a very twisting relationship between the superior mesenteric
artery and the abdominal aorta if I were to draw this there is a very large abdominal aorta
there is the SMA coming down and nestled between the two is the left renal vein if there's any sort
of aneurysm either in the SMA or much more likely the abdominal aorta that left renal
vein can become entrapped now that's going to jeopardize the return of blood from the left
kidney it's also going to jeopardize the return of blood from several other sources because on the
left side there are certain structures that drain into the left renal vein whose veins typically on
the right side drain directly into the inferior vena cava these include the left gonadal vein
the left inferior Franek vein and the left super renal vein you can see those two are
sharing a common trunk there so with left renal vein entrapment syndrome
also known as Nutcracker syndrome because this looks like a nutcracker
we're compromising blood flow from the left kidney the left side of
the inferior diaphragm the left super anal gland as well as the left gonad symptoms may
include hematuria which is blood in the urine left flank and go nate'll pain in
varicocele which are varicosities of some of the the testicular veins like the pan
pinafore plexus becomes varicose that can be very painful and uncomfortable
and that leads us to the assessment question for the video which vessels give rise to the
efferent arterioles which supply the glomeruli so let's think about this renal arteries give
rise to segmental arteries of which there are five segmental arteries so renal two segmental
segmental arteries give rise to inter lobar arteries and your lobe or arteries are going
to come around the corner of the pyramid into arcuate artery so the central lobe are
those are arcuate coming off of both arcuate and interloper arteries are those cortical
radiate arteries the cortical radiate arteries so cortical radiate give rise to the afferent
the afferent arterioles into the glomerulus where we've got filtration occurring into the efferent
arterioles which then give rise to the peritubular capillaries and veins erecta so that we can have
tubular secretion and reabsorption so the correct answer is B cortical radiate
arteries supply the afferent arterioles to the glomeruli thank you very much for your time