hello all this is dr fox let's talk about the stomach in this video we'll discuss the
structure and features of the stomach as well as how it relates to other viscera within the abdomen
the stomach is an organ of the foregut the foregut begins at the beginning of the abdominal
esophagus and it ends at the major duodenal papilla of the second part of the duodenum
and as you can see the stomach is the largest portion of the floor gut
the stomach is preceded by the esophagus boluses so those are food mixed with saliva traverse the
esophagus and enter into the stomach for further digestion they enter at the cardiac orifice and
succeeding the stomach and the processes of digestion chyme which is that transformed
substance from the bolus is ejected through the pyloric orifice through the pyloric sphincter into
the duodenum the stomach is a rather expansive organ so as it is loaded with more boluses it can
accommodate that volume and it can then contract back into its original size and uh and orientation
as it expands folds of the lining called gastric rugae rugae are ridges
largely go away and as the stomach settles back into its original form
those rugae reform are curvatures to the stomach there is a greater curvature
the greater curvature starts at this cardiac notch and it extends left laterally
all the way to the pyloric orifice the greater curvature of the stomach is in association with
the greater omentum and there are three components of the greater omentum that are going to connect
the stomach to other aspects of the abdominal cavity so there is a gastrophrenic ligament
that gastrophrenic ligament runs from the greater curvature of the stomach to the diaphragm
there is a gastrosplenic ligament which connects the greater curvature of the stomach
to the spleen and then finally a gastrocolic ligament which connects the greater curvature of
the stomach to the transverse colon oftentimes this is referred to as the omental apron
and it's called that because it hangs down anterior to the uh the small intestines
and to the the transverse colon and it is richly imbued with adipose connective tissue
there is also a lesser curvature of the stomach the lesser curvature of the stomach begins
at the cardiac orifice and it extends over to the pyloric orifice and it consists of an attachment
to the liver called the hepatogastric ligament hepato liver gastric stomach
which is a part of the lesser momentum so lesser curvature is associated with the lesser momentum
the other part of the lesser momentum which will be discussed in another learning objective
is the hepato-duodenal ligament which is going to run from the porta hepatis of the liver
down to the duodenum stomach has three major parts there is the body of the stomach the body runs
from a plane a horizontal plane that starts at the cardiac notch and extends to the greater curvature
and it runs down to another plane that begins at the angular incisure of the stomach and then there
is an oblique plane that runs over so this area is the body the region of the body which is adjacent
to the cardiac orifice is called the cardiac region which i'll surround there superior to the
body is the fundus the fundus is everything that is above that plane from the cardiac notch to the
greater curvature and then there's also the pyloric part the pyloric part begins at that plane
from the angular incisure down to the greater curvature all the way out to the pyloric orifice
the pyloric part is generally divided into two segments the uh the segment which is proximal
is called the pyloric antrum or just antrum and that runs from that angular incisure plane
over to another plane there is a very inconstant uh they call it the intermediate sulcus
that can sometimes be seen from the serosal surface of the stomach
and anything distal to that plane is called the pyloric canal sometimes just called the pylorus
oftentimes the pylorus is referred to as the area that is inclusive of the pyloric sphincter that
would be the aggregation of sphincteric smooth muscle that's separating the pyloric part from
the duodenum as well as the pyloric orifice which is the space or the lumen within that sphincter
the stomach is supplied by blood through a variety of sources and the sources are derivatives of
the celiac trunk the celiac trunk is the dominant blood supply to the derivatives of the foregut and
there are three major branches to it and we'll discuss the branches and uh their components and
a subsequent learning objective but there is a left gastric artery the left gastric artery
supplies the lesser curvature of the stomach as we can see there
there's also a right gastric artery the right gastric artery is
a branch of the common hepatic artery so the common hepatic artery is what originates
from the celiac trunk and then it becomes the hepatic artery proper also known as H-A-P or HAP
and that right gastric artery is a branch of the hepatic artery proper
that also serves the lesser curvature and very frequently anastomosis even
openly anastomosis with the left gastric artery to serve that lesser curvature
the uh common hepatic artery also has other branches which serve the uh stomach so if
we follow that common hepatic artery along we see that there is a gastroduodenal artery
that gastroduodenal artery is going to be the star of subsequent learning objectives with respect to
blood supply to the duodenum and pancreas and one of its branches is the right gastro-omental artery
also known as the right gastro epiploic artery so you may hear it referred to as either of these
names the right gastro-omental artery serves the greater curvature of the stomach as well as the
greater omentum or the omental apron there is a counterpart to this a left gastro-omental or
left gastroepiploic artery which is a derivative of the splenic artery as we can see here which is
a direct branch of the celiac trunk that left gastro-ometal artery or gastroepiploic artery
is going to serve the greater curvature of the stomach and anastomose often openly with the right
gastro-omental artery so the gastro-omental arteries are going to serve the greater curvature
the gastric arteries are going to serve the lesser curvatures there are also
short gastric branches of the splenic artery which are going to serve the fundus of
the stomach so those are short gastric branches so as you can see here we have a variety
of sources of blood to the stomach and anastomoses are quite plentiful
with respect to the innervation of the stomach or the autonomic innervation of the stomach there
are two major sources here there is the the celiac plexus the celiac plexus originates at the celiac
ganglia so here we can see let me switch colors here so we can see them better
so here are those ganglia and there's a little bit of plexus between them
those celiac ganglia are where um two of the three thoracic splanchnic nerves so
these are pre-ganglionic sympathetic fibers that are coming from the the thoracic
spine moving through the paravertebral ganglia without synapsing and then moving down um
traversing down through the the crura of the diaphragm before finally synapsing in the celiac
ganglia so the greater and the lesser thoracic splanchnic nerves will will move through there
also the posterior vagal trunk will also have fibers that move through those ganglia
but will not synapse there and so fibers of the thoracic splenic nerves and posterior vagal trunk
will then form the celiac plexus and the celiac plexus will be distributed to organs of the
foregut through the celiac trunk and its branches so these autonomic plexuses can deliver their
fibers along the uh the blood vasculature conduits also serving the stomach will be fibers from the
anterior vagal trunk not shown here these vagal trunks are going to enter the abdominal cavity
along with the esophagus so they're going to be transmitted through the esophageal hiatus
at approximately the t10 level anterior trunk will be anterior to the esophagus posterior trunk will
be posterior to the esophagus and as you can imagine with the proximity of that abdominal
esophagus to the stomach these fibers aren't going to have a very long distance to go in order to
find their targets within the walls of the stomach
now in terms of action when we think about the divisions of the autonomic nervous system
there's the parasympathetic which is the rest and most importantly here digest
as well as the sympathetic which is the fight or flight and so parasympathetic stimulation is
going to stimulate the smooth muscle of the walls of the gut tube that will cause it to contract
and enhance gastric motility it will also relax the the sphincters which are flanking the stomach
as well as encourage the gastric mucosa to secrete sympathetic stimulation will do
just the opposite it will be involved in vasoconstriction but it will also inhibit smooth
muscle contraction or inhibit motility as well as tighten the sphincters that flank the stomach
general visceral affair fibers or GVA accompany both sympathetics and parasympathetic
fibers in terms of the gva fibers which accompany the sympathetic fibers these are going to
transmit visceral pain so it's not true pain but any sort of distension or tearing or
burning will transmit information along these general visceral afferent fibers
which are going to mirror the distributions of the sympathetic fibers and this referred pain
is going to be felt in the epigastric region so the epigastric region or the epigastrium
if you put your hand right at your uh your xiphoid process that's kind of um almost central within
the epigastric region that's where any referred pain from the stomach is is going to be felt
so we've talked a bit about uh the constituent parts of the stomach how the lesser and
greater curvatures of the stomach relate to elements of the lesser and greater omenta
we've discussed blood flow to the stomach we've discussed the autonomic innervation
of the stomach this is your summary slide thank you very much for your time