Hello all this is Dr. Kathleen Alsup and I'm going to provide a quick
overview of the pancreas. The goals of this lecture are to provide you with the
scaffolding to really better prepare you for the anatomy dissection experience
but as you know sometimes those don't always align exactly with the clinical
and other basic science lectures, so we wanted to provide you the basics here
first. Let's get started in terms of getting a better understanding of where
the pancreas is located. The pancreas is rather deep in terms of its placement
and the majority of this particular organ is going to be what's referred to
as retroperitoneal and i have an asterisk here most resources you'll see
that the pancreas is exclusively retroperitoneal and that's true the
majority of the organ is but I want to note right here and you can see it
better in this particular image that the tail of the pancreas is very closely
associated with the spleen we know the spleen is an intra-peritoneal organ
therefore the tail of the pancreas is as well. So everything from about here on is
going to be retroperitoneal and it makes sense you have this very close
relationship to the kidneys but the tail of the pancreas is going to be considered
intra peritoneal. The pancreas is an accessory digestive gland so really
thinking about that exocrine function those pancreatic enzymes but you will
also have an endocrine function that's very important in terms of the pancreas
in terms of the secretion of insulin. So let's better understand the parts of the
pancreas the head of the pancreas you can see right here fitting right into
this C shaped portion of the duodenum this is the thickest portion of the
pancreas and it's on its way to opening into the descending part of the duodenum
so the bile duct lies in a groove on the posterior superior surface of the head
and really it's embedded right within that parenchyma the pancreas the
uncinate process which you can see a little bit right here also affords a
very close relationship with the duodenum this is actually just a
projection of that inferior part of the head and this
portion the incident process really developed separately in utero from the
rest of the gland so it does have a slightly different appearance and the
rest of the head of the pancreas the neck which we don't have labeled in this
image but it's right about here the neck as any good neck does is located between
the head and the body of the pancreas it is really important due to its
relationship to the hepatic portal vein which is it's located anterior to that
hepatic portal vein so if you have any issues in terms of the prank amount of
the pancreas it could actually affect the portal vein deep to it the body of
the pancreas is the longest part and is considerably thinner than the head it's
superior portion is very close related to the celiac trunk and its branch the
splenic artery which you can see right here we always say that splenic artery
has a very torturous relationship it's kind of a squiggly artery right here
very large which makes sense because it's going to supply the spleen
posterior to the body it's related to the SMA or your superior mesenteric
artery the aorta and even portions of the left kidney and you can see a fairly
large tail in this particular individual of the pancreas it's not always quite
that large but it's very closely related to the hilum of the spleen and as I
discussed before this is considered intraperitoneal now if we're looking
back at the head again of the pancreas this is really where you're going to see
the bulk of the pancreatic ducts now pancreatic ducts transport that
exocrine material of the pancreas so those pancreatic fluids and that
eventually needs to make its way to the descending or second part of the
duodenum the major duct of the pancreas is referred to as the main pancreatic
duct sometimes you just see it referred to as the pancreatic duct and you'll
really find it in your dissection traveling from the tail of the pancreas
all the way towards the head of the pancreas and this is the duct that's
going to join the common bile duct to enter into the
duodenum and this joining will form a dilation you can see it very well in
this particular image this dilation right here is referred to as the hepato
pancreatic ampulla and this is opening into that second part via the major
duodenal papilla so the major duodenal papilla would be right in this region
Commonly there is also what's referred to as an accessory pancreatic duct so
very much involved with the head of the pancreas and you can see here this is a
really nice example these ducts often communicate the fluids transported by
the accessory pancreatic duct enter the duodenum via the minor duodenum papilla
so you would have the major duodenal papilla here the minor duodenal papilla
here so that's going to be superior to the major so typically that's going to
be the typical pattern sometimes you'll have no communication every once in a
while the accessory pancreatic duct is actually larger than the major but this
is the typical pattern here now I know this particular slide seems a little
overwhelming and the arterial supply of the pancreas can't seem overwhelming but
really these names really explain exactly where they're supplying so if we
can kind of get over the the length of the name I think you'll actually find
that it's very explanatory of what it's supplying. We can really divide the
arterial supply into what supplies the head and the neck and what supplies the
body and the tail so we're going to start with the head and the neck and
also the head and the neck of the pancreas shares the supply with the
duodenum which makes sense based on it's very close relationship. The head and the
neck of the pancreas are going to be supplied by the celiac trunk which you
can see here so branches of that celiac trunk and branches of the superior
mesenteric artery whereas the body and the tail are going to be supplied
exclusively by that splenic artery so let's get into a bit more details in
terms of the head and the neck supply on both sides of the head and neck region
there are what we call arterial arcades and really what that is is just a
network of anastomosing arteries and we're going to
start— both these arcades are going to have what's referred to as superior and
inferior branches and they're coming from the celiac trunk or the SMA so
let's start with the anterior pancreaticoduodenal arcade.
The anterior superior branch, which you can see right here, is derived from the gastroduodenal
artery and the gastroduodenal artery is one of the terminal branches of the
common hepatic artery and if you think back to just the basics of the celiac
trunk, that's one of the three main branches of the celiac trunk so the
source is going to be celiac for these superior branches whereas when
we're talking about the anterior inferior branches these are going to be
derived from the inferior pancreaticoduodenal arteries
and these are a direct branch off of that sma so one of your
first branches in fact of your superior mesenteric artery. The posterior
pancreaticoduodenal arcade is similarly organized with the posterior superior branches,
from gastroduodenal, and posterior inferior branches
from the inferior pancreaticoduodenal,
or your sma
so don't forget it's very important to note that these arteries not only supply this head and neck region,
but also the duodenum.
thus the name pancreaticoduodenal. It's really less complex in
terms of the rest of the pancreas so these are all going to be derived from
branches from the splenic artery the dorsal pancreatic artery is really the
largest branch that we're going to see typically and it's generally one of the
first if not the first branch off the splenic artery and it will continue
inferiorly as the inferior pancreatic artery so you can see it extending right
here and as its name would suggest on that inferior portion of the body. Unlike
its name would suggest, the greater pancreatic artery is actually not
particularly large it's a bit more lateral of a branch from the splenic
artery that's going to supply the more lateral portions
of the body but the very aptly named artery of the tail of the pancreas is the
main supply for the tail of the pancreas but also coming off of the splenic artery.
now in your dissections these arteries
are often easier to locate on the posterior side of the pancreas. The
venous drainage is considerably easier to understand after a discussion of the
arteries there will be similarly named veins and tributaries to what we have
with the arteries and they're all draining into the hepatic portal system.
So not into the systemic system but into the hepatic portal system. Lastly we
can't forget innervation like most of the viscera in this area, the pancreas
has both parasympathetics derived from the vagus nerves innervation as well as
sympathetic innervation from those thoracic splanchnics,
particularly that greater splanchnic and the lesser splanchnic, and as in most of the
functions parasympathetics is going to be secretomotor and sympathetics will
be vasoconstrictors in terms of the vasculature associated with the pancreas
in common with other foregut structures the majority of pain arising from the
pancreas is referred to the epigastrial region so remember that's just anterior
to the stomach or the central superior abdominal area. So this concludes the
overview of the pancreas for additional information and images please refer to
the BlueLink website.