Hello, all, I'm Glenn Fox
and in this video, I'll discuss the duodenum my objectives for this video are for you to understand the relative location gross anatomy and
neurovascular of the duodenum
like the stomach the duodenum straddles both the left and the right upper quadrants, although the duodenum is
more in the right upper quadrant than it is the left upper quadrant as
Part of the gut tube the duodenum connects the stomach
with the jejunum
The jejune is a continuation of the small intestine of which the duodenum is apart
There are four parts to the duodenum
the first portion of the first part of the duodenum is intraperitoneal and the second third and fourth parts are
retroperitoneal
You can think of the duodenum in
roughly a c-shape and in the crook of that C
The duodenum cradles or snuggles the head of the pancreas and
That's an important relationship because in the second part of the duodenum
we have the major duodenal papilla and
That major duodenum papilla receives the heapatopancreatic ampulla that hepatic pancreatic
ampulla is a dilation of the tubes that drain the liver and gallbladder as
Well as the pancreas so that those secretions may enter into the second part of the duodenum
That major duodenal papilla is
an anatomical and embryological landmark that differentiates between
the embryonic foregut and
The embryonic midgut so it's there in the second part of the duodenum that we have the divisions between
the foregut and the midgut
although some classifications would put that line between the second and part of the duodenum as
It's receiving so many secretions from the liver gallbladder and pancreas
The duodenum is a major site for chemical digestion as well as absorption
As I've said before there are four parts to the duodenum
the
superior or first part of the duodenum
receives chyme
from the stomach through that pyloric canal
the second or descending part of the duodenum
receives secretions from the gall bladder liver and pancreas
Through the major duodenal papilla if there's an accessory pancreatic duct present
That accessory pancreatic duct drains through a minor duodenal papilla
Which is typically more proximal in the gut tubes in the major duodenal papilla
and it's here within the second part of the duodenum that we have that division between
embryonic foregut and mid gut
The third or the horizontal part of the duodenum is
Retroperitoneal and it's crossed over by the superior mesenteric vein and
superior mesenteric artery and so here is
Where the duodenum is at risk for superior mesenteric artery syndrome
So an impingement upon that third part of the duodenum between the abdominal aorta and the superior mesenteric artery
the fourth or ascending part of the duodenum is
supported by a
suspensory ligament also known as the ligament of Treitz and then it feeds
Into the jejunum and the remainder of the small intestine
The duodenum and
by its association the head of the pancreas is
supplied by the pancreaticoduodenectomy
arteries which is you may recall is a branch of the common hepatic artery
This gastroduodenal artery is going to branch into anterior superior pancreaticoduodenectomy
pancreaticoduodenal artery, so these are really going to
From the superior hug both the duodenum and the head of the pancreas
inferiorly the superior mesenteric artery or the SMA
Which is a major branch of the abdominal aorta just distal to the celiac trunk is
going to supply the duodenum and head of the pancreas by the
inferior
pancreaticoduodenal artery and that inferior pancreaticoduodenectomy
C are open anastomosis between the anterior superior pancreaticoduodenal artery
pancreaticoduodenal artery and anterior and posterior branches of the inferior pancreaticoduodenal
artery
veins which drain this region are typically named in accordance with their accompanying arteries and
all of these are going to flow into the
superior mesenteric vein and
Then the hepatic portal vein
The duodenum as part of the gut tube is innervated by the
enteric nervous system, which is comprised of
the my enteric and submucosal plexus ease which are part of and controlled by the
autonomic nervous system
the sympathetic
influx
Into the duodenum
comes
from the
thoracic
splanchnic nerves in particular the greater and
lesser splanchnic nerves
the greater
typically is
T5 through
T9. The lesser typically will receive fibers from t nine and
ten
Sometimes nine
ten and eleven
and these pre ganglionic sympathetic fibers are going to spread out at the root of
the celiac
Artery, they're going to synapse in the celiac ganglion and then the postganglionic
fibers are going to spread out as
sympathetics within the celiac plexus
when active the sympathetics are going to encourage vasoconstriction a decreased motility of the gut and
Will also conduct the visceral afferent fibers which are those visceral quote unquote
pain fibers which aren't really pain but your brain interprets it as pain and this referred pain is
Felt in the epigastrium
The
parasympathetics to the duodenum come from
the posterior vagal trunk
that posterior vagal trunk will flow to and through without synapsing in the celiac ganglion and
then will distribute themselves about the
celiac and
Superior mesenteric
plexus
when active the parasympathetics are going to encourage both secrete a motor function of the gut as
Well as gut motility
Thank you for your time. And if you have any questions, or if you're in need of further visuals
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