the

Abdominal organs (plastic anatomy)

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hi one of them was a kid I knew about

the organs of the body but I couldn't

work out how they all fit in I I think I

assumed they must be neatly organized

with the bit of space in between them

probably the the illustrations of the

time for children showed that sort of

thing I couldn't really work out he

wasn't even through all my school years

it wasn't until I got to University and

I started taking bodies apart that I

realized wow this stuff is really packed

in here we had a comment was he last

week somebody asked could I go through

all the abdominal viscera and I thought

and then I was teaching last week chat

to a student she wasn't entirely sure

where the stomach was so I thought

that's a good idea that we should go

through all of the abdominal viscera

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so yeah my father I've had an

interesting Anatomy for a very long time

and it hasn't really disappeared and I

think the stage I'm at now is the more I

the more we know the more I realize I

don't know and the more I try to hold in

my head the harder it is for me to hold

everything in my head

that makes any sense at all this but

same with other things you become an

expert you realize you don't know

they're very much a tool anyway right so

what is the abdomen and then what we'll

do is we're gonna take all these parts

away from the model so as we go we'll

point things out as we remove things

we'll try to see the pay attention to

what lies posterior to that organ or

near buys we've got an idea of where

things aren't relative to one another

also remember that whenever we're

talking about the body whenever we use

left or right we're talking about the

body is left and the body is right

okay not our view but the body's left

the body's right and we'll work our way

back to the posterior abdominal wall and

see what we see so then the abdomen the

abdomen is the region of the trunk

between the thorax and the pelvis is

your typical textbook description which

sounds nice and tidy now with a superior

and is nice and tidy what we're seeing

here is the diaphragm so the diaphragm

does cleanly separate the abdomen from

the four acts so the diaphragms got kind

of this is curvy shape to it was a

three-dimensional thing he was curving

over the liver here but the diaphragm is

a is a muscular sheet that separates the

thorax from the abdomen now in feelingly

it's a little bit harder because the

pelvis well here's the pelvis and the

pelvis has these bony parts so much of

the pelvic viscera is down here but this

is pelvis but the abdomen also extends

all the way down here so

what's happening is that the the

contents of the abdomen are covered in

the layer of peritoneum like a like a

thin sheet so it's almost like all of

these contents here like it's all in a

bag and when that bag sinks down into

the pelvis the abdominal contents have

sat on top of the the pelvic contents

the pelvic viscera and is the peritoneum

then that's really separating the pelvis

the pelvic viscera from the abdominal

viscera so then that distinction between

abdomen and pelvis is a little bit

softer down here and of course when

women get pregnant and the uterus

becomes in last or even when you buy

either filled with you and that becomes

enlarged those push from the pelvis up

into the abdomen so there's a bit of

interplay between the abdomen and the

pelvis okay what can we see so we see

some organs up here the biggest organ is

the liver is very big organ it's on the

right side of the abdomen but it's

extending across the midline to the left

side it was a very large organ and it's

just underneath the diaphragm so as the

diaphragm moves up and down as well the

liver will move up and down with us they

didn't interplay between the four legs

and the abdomen there so there's the the

liver and then nestling into the liver

on the left side this is the stomach so

the stomach as you can see it's pushed

up into the liver you know if we take

that knocked off if we lift the liver up

that's how we'd see the stomach nestling

into the liver there do you see -

they're very tightly stuck together

diaphragm diaphragm and of course the

esophagus passes down through the

diaphragm and I pop this over there's

the esophagus this who dives through the

diaphragm there's a hole in the

diaphragm now if I put the liver back

this here so if we if we're if we take

away the skin we take away the muscles

of the anterior abdominal wall and we

take away the peritoneum lining the

parietal peritoneum lining

Damo cavity we see this here and this is

the greater omentum this gets called the

the policeman of the gut now what it

does is it's a connective tissue sheet

that's hanging down from the greater

curvature of the stomach and it's

covering all of these organs down here

and it's again it's layers of peritoneum

it's got fat in it it's got blood

vessels its job seems to be is that if

there is some inflammation in the bowel

down here it will inherit my

inflammation and help prevent is

spreading too far everyday the greater

omentum off now we can see the GI tract

the GI tract will the gastrointestinal

tract is the bulk of four viscera that

we find within the abdominal cavity it's

a long continuous tube from the soffit

as' and stomach through the small

intestine the large intestine all the

way through to the rectum and the anal

canal the rectum is in the pelvis and

the anal canal is in the perineum

now what we see is we can see a little

bit of large bowel here this is the

ascending colon and we see a little bit

of large bowel here this is a transverse

colon and then we see a little bit of

large bowel around there the descending

colon so this is large colon or large

bowel this then is the small intestine

or the small bowel if we remove the you

see how the liver and the stomach a loss

superior and this stuff is squashed up

against it if I remove the liver here's

the stomach and the stomach is

continuous with all of this we we often

see in models and textbooks that the

transverse colon runs across here we

looks like a picture frame around the

small bowel in you if you're sat up your

transverse colon is probably dropping

drooping down a little bit like that if

you're looking at abdominal x-rays the

transverse colon probably is going to do

this it's probably going to be looping

down here because it's actually got a

mid-century so the knees entry is a

double fold of peritoneum with so that's

how the blood vessels and nerves and

lymphatics get to and from the bowel and

because the the transverse codons got a

meeting Terry means it can move around

the ascending colon and the descending

colon are fixed in place to the

posterior abdominal wall so they don't

move around the small bowel also has a

reason tree so it is fairly mobile and

of course what's happening is the food

is being passed into the stomach and

then it gets pushed into the small bowel

and peristalsis and the shortening and

lengthening of the small bowel pushes

the foods along the small intestine and

the nutrients get absorbed from it and

then it gets pushed into the large bowel

which largely agree absorbs water and

that sort of thing so it's helpful if it

if it moves around right okay so stomach

now if we take away this stomach we can

see some other viscera deep to that so

this here this is the pancreas so the

pancreas is doing two things it's making

hormones that it secretes into the blood

to steady blood glucose levels and it's

making an exocrine secretion of

pancreatic juice that it's going to

secrete into particularly the transverse

colon the duodenum here so the duodenum

is the first part of the small intestine

and it's forming a C shape it's curling

around the pancreas here so the pancreas

has got this duct and it's going to

secrete into the duodenum to help with

digestion of the contents that you just

eat and that the stomach is pushing into

the joint deal right pancreas duodenum

so out here

that's the spleen the spleen is at the

tail of the pancreas it's on the lateral

left side of the body

you got one pancreas you've got one

spleen so the spleen is a component of

the immune system it's a store of red

blood cells it's a store of platelets so

it can help with clotting and help with

replacing red blood cells if you lose

them if you have an injury losing your

loose of blood that sort of thing

there's also a site where you find lots

of lymphocytes and macrophages and it's

a site where parts of the immune system

are stored and where pass the immune

system can be activated in things like

that so it's got a couple of big roles

not least immunological in fact it sends

red blood cells once it's broken them

down to the liver which is nearby it's

got a blood vessel and it sends across

the liver of a liver has got 500 all

different functions it's got a huge

number of jobs it has a huge amount of

blood passing through all the blood from

the GI tract passes through the liver

and the liver is wrapped around the

inferior vena cava which we'll see more

of as we get deeper so blood from the

gut and the spleen passes through the

liver to the inferior vena cava back to

the rest of the circulation okay so

small bowel now the duodenum is the

first part of the small intestine it

passes food into the jejunum and the

judgment becomes the ileum so the small

intestine isn't the same along its

entire length food passes so the

judgment is out on this side and the

idea is over on this side and food

passes along the length from the

duodenum to the jejunum to the i liam

and if you look at the histology and the

structure of the small intestine as we

go along its length it changes slightly

and it has slightly different roles so

if we take the small intestine out we

can see that the small intestine is as I

said it's kind of suspended strung from

the posterior abdominal wall by

mesentery so this can all move around

now we've taken off the small intestine

we can see that Julie Dean and this is

the curve I was talking about here first

part second part third part that it goes

up again fourth part and you can see

here this is where the pancreas secretes

into the duodenum in fact the other

thing we've got here is you might have

spotted it it's the green bit there that

there is the gall bladder

so the google bladder is storing bile

and it's gonna pass that bile through

some ducts eventually down into this

point here so the common bile duct is

going to pass bile into the duodenum

here the same point of the pancreas

passed into the duodenum and the bile is

also going to help with digestion is

going to help emulsify fats and that

sort of thing and remember those five

hundred different jobs that the liver

does well some of the waste it produces

is going to get passed into the small

bowel to be removed from the body

through the common bile duct through the

same route

that's why behind is green and that's

what makes feces brown in fact it's it's

recycled red blood cells anyway so

duodenum here now what else can we see

so we can see the ascending colon and

the descending colon little bit better

we can see the posterior abdominal wall

and we can see some of the blood vessels

supplying blood to the large bowel here

now on the superior edge of the pancreas

so if I take this off we just jump ahead

we can see the major blood vessels this

is the a or to the abdominal aorta the

abdominal and so the aorta is supplying

blood to the four act to the abdomen and

eventually it's going to send off

branches to the pelvis and the lower

limbs and what-have-you that's the aorta

now the aorta has got three anterior

branches and those anterior branch is

going to supply blood to most of the

things in the abdomen so just superior

to the pancreas we have the celiac trunk

and you can see it's sending off

branches to the pancreas to the spleen

to the

gentleman off to the liver and that sort

of thing now only inferior side of the

pancreas we can see the superior

mesenteric artery and the superior

mesenteric vein the superior mesenteric

artery is a branch the aorta the

superior mesenteric vein is going to be

sending blood back to the portal vein

and the liver down here we can see the

bladder so the bladder is in the pelvis

normally that if we had peritoneum here

the bladder would be covered over by

peritoneum and that would mark the

inferior end of the abdominal cavity

that's where the abdomen end the

descending colon then becomes the

sigmoid colon here as it makes a bit of

an S shape and Wiggles around and when

it goes back there and straightens out

it becomes erect and that's what the

rectum means

rectum rectus means straight so the

rectum is the straight part of the large

bowel and the last part for the anal

canal all right if we take that off then

we can see the aorta and next to is the

inferior vena cava so this is going to

carry blood back from the abdomen the

liver is going to send blood inferior

vena cava and then that's going to go

through the diaphragm and straight back

into the heart into the right side of

the heart into the right atrium and then

off around the body

there's the superior vena cava up there

so inferior vena cava a Horta we can see

a whole bunch of blood vessels branching

from where the really important ones are

on here and of course we can see these 2

these are the kidneys so the kidneys are

posterior in the abdomen they're in the

posterior abdominal wall

they are posterior to the peritoneum

that connective tissue layer so they get

called retroperitoneal so the kidneys

are receiving a huge amount of blood

steak or some big blood vessels you see

the veins here because the the renal

veins are anteriors that the left renal

vein has to run quite a long way and

it's running it's running anterior to

the aorta but the the renal arteries are

posterior toes and they're gonna be

large is what's a large blood

supplying small organs mean that these

organs are doing something with the

blood and they're processing the blood

of course what they're doing is is

largely managing the amount of fluid

inside the body you are a bag of salty

water that's what your cells evolved

from and now you have a bag that you

carry that salty water around in you

have to maintain the right amount of

salty water and the microlight of salt

in it for yourselves to be happy to

function normally

so that's largely what the kidneys are

doing they're managing all of that so

then from each kidney we can see these

so these are the ureters and the ureters

then again s passed urine from the

kidney down to the bladder and then on

the posterior abdominal wall overlying

these muscle cells you see a number of

muscles making up the posterior

abdominal wall now in the superior pole

of each kidney we have a suprarenal

gland or an adrenal gland

now the adrenal glands make adrenaline

adrenaline and noradrenaline obviously

that's involved in the fight-or-flight

response in the adrenaline rush in that

activation of the sympathetic nervous

systems you can fight or flight fight or

fly fight off fly away run away and they

also make a whole bunch of steer or it's

deal with always glucocorticoids

mineralocorticoids that sort of thing

which manage you know manage homeostasis

manage metabolism and that sort of thing

so again related to the gut and energy

and food and that sort of thing so

you've still got the spleen out here so

can you see how the spleen is typically

it's a little bit of posterior but its

lateral can you see how it's nestling up

into the diaphragm whereas the kidneys

are a little bit more inferior and the

left kidney do you see it's a little bit

higher than the right kidney and that's

because of the liver so the liver is so

big it's actually pushing the right

kidney so it's a little bit lowering the

abdomen

so if you were to look at a transverse

section across here you might see just

one kidney on one side and the spleen

and all these other bits if you might

miss the other kidney go a bit lower

you'll get a section through both kids

using both on CT or mr you can see the

diaphragm then arching back there these

these thick muscles here these are the

psoas muscles the psoas major and it's

got a little psoas minor lying on the

top of it

this is iliacus and these two muscles

will join insert into the femur and give

hip flexion so now lift your knee toward

your chest these muscles here these are

quadratus lumborum and they're running

kind of what kind of in that direction

from the vertebral column to the pelvis

which will give you a little bit of

lateral flexion of your trunk all right

these arteries here these we were

talking about last week these are the

testicular arteries running from the

aorta in the abdomen all the way down to

the scrotum because the testes started

to form up here and then they descended

in the in the embryo and the fetus and

they trailed their blood vessels behind

and you can see the testicular veins

draining back the left one goes to the

left renal vein and the right would go

threatening the inferior vena cava

so the aorta ends when it divides into

left and right common iliac arteries

that's what we were seeing here the left

and right common iliac arteries then

divide again into an external iliac

artery which is going to run down to the

lower limb one then to the thigh in the

leg and then an internal iliac artery

which is going to go down into the

pelvis and supply blood to the vserver

of the pelvis and also to the external

genitalia and that sort of thing so I

take the stomach off there's the

pancreas and if I take the pancreas off

there's the kidney it's that's that

that's a sort of layering that we're

dealing with can you see the adrenal

glands they're just popping up now the

aorta you can't see it because he's just

running through a

gap in the diaphragm there but the the

inferior vena cava has just been cut

because we've removed the liver and

that's it I can't say kind of thing else

off if I was to take more off would be

at the muscles and I take the muscles

off and we be at the other side that's

what you find inside the abdominal

cavity if you take things out bit by bit

well I enjoyed that as a thank you for

that suggestion it did remind me of if I

was like when I was a kid kind of work

out how all this stuff was packed in and

where it all was exactly now I do kind

of take it for granted but there you go

okay see you guys next week

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