hello all this is dr alsup and thank you for joining me for another fun yet informative
learning objective video now this is another video where we're really going to focus on defining
some terms that we will be using throughout our discussions in gastrointestinal anatomy
specifically we are going to be defining and providing examples
of excuse me the terms intraperitoneal primary or primarily retroperitoneal
secondarily retroperitoneal and last but not least subperitoneal so let's start with intraperitoneal
organs as these are quite numerous when we're talking about the abdominal cavity intraperitoneal
organs are almost completely covered in visceral peritoneum and you can see that kind
of really nicely right here in this image so all surfaces are going to be covered in peritoneum or
almost all surfaces these organs are going to be suspended within the abdominal cavity but not
inside the peritoneal cavity so invaginated within the peritoneal cavity similar to most complexes of
serous membranes remember the example of the fist being the organ so having that visceral peritoneum
that is going to be covering the organ or the fist as you in the example the parietal serous
portion is going to be on the outside
and there'll be those continuations and then the peritoneal cavity or um you know in other
examples obviously in terms of the pericardial cavity when you're talking about the heart
that would be in between so it's not within the cavity but it's going to be invaginated within
all right as mentioned many of the abdominal organs are intraperitoneal
so that includes the stomach the liver most of the small intestine the cecum
and the appendix which is attached to the cecum the transverse and sigmoid colon
gallbladder and even the spleen are going to be examples of intraperitoneal organs
okay moving on to retroperitoneal organs of which there are two types but more generalized
all retroperitoneal organs are located posterior to the peritoneum
so closely associated with the posterior abdominal wall most retroperitoneal structures will have
peritoneum covering their anterior or maybe even a little bit of their lateral surfaces
primary or primarily retroperitoneal structures develop so embryologically develop and stay
retroperitoneal so always retroperitoneal some examples of these will include
kidneys and suprarenal glands the the ureters the larger vascular structures like the inferior
vena cava and abdominal um aorta so you can see those right here those are going to be examples
of primary retroperitoneal organs the other category of retroperitoneal structures are
secondary or secondarily retroperitoneal organs and these organs actually develop
intraperitoneally so it's going to have a little mesentery associated with it early in development
so it will be covered with the visceral peritoneum and further into the abdominal
cavity but as development progresses this organ is going to be drawn towards
the posterior abdominal wall as you can kind of see happening from here to here
and um it will actually be drawn all the way to the posterior abdominal wall and only be covered
with peritoneum on the anterior surface so the descending colon is the example of that
the rest of that peritoneum that had been covering it will transition into what's referred to as
fusion fascia which creates avascular planes of connective tissue that allow during say a
surgery a greater degree of mobility and ease of accessing structures without fear of injuring
vascular structures because as mentioned these planes of fusion fascia are going to be a vascular
i really like this image below it really shows kind of a step-by-step process of a
secondarily retroperitoneal structure because this is often conceptually difficult to
to think through so you're starting off intraperitoneal with an associated mesentery
like other intraperitoneal viscera and then it starts to move posteriorly until it is firmly
adhered to the posterior abdominal wall as you can see there so you lose any of that peritoneum
that was associated with the posterior portion of the organ and that previous mesentery transitions
into more of a fusion fashion so some examples of secondarily retroperitoneal organs include
most of the duodenum the ascending and descending colon and most of the pancreas
lastly let's not forget subperitoneal organs and we aren't going to spend much time here because
we're going to spend a bit more time on these when we get to pelvic anatomy but recall that
the peritoneum does not or does excuse me it does certainly extend into and ends in the
pelvic cavity so that inferior most extent of the peritoneum lies over the superior surfaces
of some of the viscera in the region such as the bladder and the inferior portion of the rectum
when we're looking at the uterus here it's actually going to be covered in
peritoneum on most of its sides so it will be considered intraperitoneal
and here is the summary slide make sure you understand the difference between intraperitoneal
primary and secondarily retroperitoneal and of course subperitoneal organs and you
should be in a great place think of which surfaces does peritoneum cover on an organ
so for example for intraperitoneal organs it's going to be almost all surfaces retroperitoneal
just on the anterior surface of that organ and subperitoneal just on superior surfaces
excellent thank you for your time and attention here and please always feel
free to reach out with any questions i hope you have a great rest of your day