hi this is dr fox let's talk about the duodenum and the pancreas as you recall the duodenum
is proceeded by the stomach which moves chyme into it for the processes of further digestion
and absorption the duodenum is succeeded by the jejunum which continues the process
of absorption the duodenum is a c-shaped organ which enjoys a very close relationship to
the pancreas now the duodenum consists of four parts the first part of the duodenum
is known as the superior part of the duodenum and it's approximately five centimeters in length
the first two and a half centimeters of that is going to be intraperitoneal because
it is contiguous with the stomach and it's that second part where the duodenum moves to be retro
peritoneal specifically retroperitoneal because it is pulled behind the peritoneum during development
the first part or the superior portion of the duodenum is very identifiable from the
remaining parts by its mucosa because it is rather smooth-walled the remainder of the mucosa within
the duodenum will have circular folds which slow the movement of material and increase surface
area for absorption now the second part of the duodenum is also known as the descending part
it moves from approximately the L1 level down to the L3 level and it's here in the second part
that we'll have both the minor and the major duodenal papillae which are going to drain the
biliary tree as well as the main pancreatic duct through the major and the accessory pancreatic
duct through the minor and we'll see this in a uh in a subsequent slide this second part
uh has circular folds and it's secondarily retroperitoneal the third part of the duodenum
the inferior part is also possessing circular folds and is also secondarily retroperitoneal
it is going to move across at approximately the l3 level and it is going to be sandwiched
between let's change the color here it's going to be sandwiched between
the sma here and the abdominal aorta and so if there's any sort of abdominal aortic aneurysm
this can impinge on the duodenum and that's a condition known as superior mesenteric artery
syndrome and that can preclude the movement of materials through the small intestine
now that that third part of the duodenum transitions into the shortest part of the duodenum
known as the ascending part the the ascending part is connected to the suspensory ligament
of the duodenum which we can't see here because it's occluded by the pancreas
that that suspensory ligament of the duodenum also known as the ligament of trites is smooth muscle
which supports this duodenal jejunal flexure and as we move from the fourth part of the
duodenum and into the jejunum we're moving from retroperitoneal to intraperitoneal
now let's take a look at the at the pancreas now the the duodenum has been pulled away a
little we can see some of the the elements of the pancreatic head or the head of the pancreas which
is rather robust in nestled within there there's an uncinate process that that runs
just posterior to the superior mesenteric vasculature let's just point out here is the
superior mesenteric vein and just left lateral to it is the superior mesenteric artery
so the uncinate process would be
a portion of the head which kind of goes behind those vessels the neck of the duodenum
is found anterior to the sma and smv that superior mesenteric vein is coming up to
meet the splenic vein and we can't see the splenic vein here but it would be
right about there and where these two meet is the beginning of the portal vein
and the origin of the portal vein is just posterior to the neck of the of the pancreas
beyond the neck is the body of the pancreas which we can see here and that body of the pancreas ends
in the tail of the pancreas which is nestled into the hilum here of the spleen now the pancreas is
like the duodenum predominantly a secondarily retroperitoneal structure and the head
neck and body are all secondarily retroperitonial the tail as its
adjacent to the hilum of the spleen which is an intraperitoneal organ is also intraperitoneal
let me erase some of these structures so we can take a good look at some of the the ducts within
now that the pancreas is predominantly an exocrine organ it does have some glandular
tissue which is endocrine in nature so those pancreatic islets or the islets of Langerhans
those are going to secrete hormones to help regulate blood glucose but
that is a small portion of the glandular tissue most of the glandular tissue is exocrine
and exocrine glands are going to feed into ducts whereas endocrine glands secrete into capillaries
and what i'm outlining here is the main pancreatic duct and we can see that this main duct
is going to traverse the entirety of the pancreas there and the glandular tissue will secrete
pancreatic juice into it and that is conducted
along this duct and it is going to meet up with the bile duct here the common bile duct at the
pancreaticobiliary junction and where these two meet that's the hepetopancreatic ampulla
hepatopancreatic
ampulla and that then will conduct the bile and the pancreatic juice through the major duodenal
papilla which we'll see in the next slide there's also an accessory pancreatic duct
which we can see here that may or may not connect to the main pancreatic duct it typically does not
but it does here that accessory pancreatic duct when present drains the superior portion of the
head of the pancreas and it is going to drain in the minor duodenal papilla which we'll see now
so here is that pancreaticobiliary junction that that we discussed so
here is the common bile duct coming down and it is joining with the main pancreatic duct here
so where the two combine we call this the
hepato
pancreatic ampulla and that hepatopancreatic ampulla is going to conduct through the major
duodenal papilla so that major duodenal papilla
is where the bile and the pancreatic juice are secreted into the duodenum
that is an important landmark because anything proximal to the major duodenal papilla within the
gi tract up to the abdominal esophagus is foregut and the midgut is what follows until we reach
the hindgut so the division between foregut and midgut is within the second part of the duodenum
the minor duodenal papilla if it is present and it is here is in association with that accessory
pancreatic duct and it tends to be about two and a half centimeters ish a proximal to the major
duodenal capilla and one last thing uh before signing off here we can see these circular rings
of duodenal mucosa which are very representative of the second third
and fourth parts of the duodenum but we're looking into the second part here
so we can see these plique circulares or circular folds of the mucosa here these
are the structures that slow the progress of chyme and increase surface area to maximize
absorption of nutrients here in the duodenum so we've talked about the duodenum and it's very
closely allied in location and in function pancreas thank you very much for your time