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‫‪Anatomy #04‬‬
‫‪Peritoneu‬‬
‫د‪ .‬دمحم علّوه‬
‫لبنى بسام سالمو‬
please see the end of the last page before you start , ‫بحكي جد روحوا شوفوها‬
Today we will continue our journey in the digestive system specifically
about the digestive organ within the abdominal cavity, including the
stomach, intestine and accessory organs: liver, pancreas, gallbladder.
Before speaking about these organs within the abdominal cavity, there is
a very important structure in this abdominal cavity, which is crucially
related to these digestive organs, which is: the Peritoneum.
what is the Peritoneum?
It is a serous membrane (serous mean fluid), those membranes are secreting
fluids developed by the human body to resist friction between movable
structure. You already studied the respiratory system and heard
something called pleura, which is similar to peritoneum (it is a serous
membrane sliding mechanism to resist friction)
So, what is the serous membrane
It is simply a membrane made of single layer of flat cells and this
membrane is continuously closed (like a sac / a balloon) and the cells
(mesothelial squamous cells) are secreting fluid inside it, in a simple way
it is: a fluid filled closed sac which surrounds the structures.
Again, the mechanism of the serous membrane: it’s very important in
the human body to resist friction between movable organs.
You know that the lungs are continuously expanding in inspiration and
collapsing in expiration . So, during inspiration (expanding / enlargement)
they will become in attachment to the thoracic wall, intercostal muscles,
ribs ... etc. If there is NO pleura, there will be a continuous friction and
evasion of the lung tissue leading to inflammation; to avoid this; we
have the pleura: which is a fluid filled sac all around the lung.
The same idea in the heart, the heart lies within a fibrous tissue (fibrous
pericardium), continuously beating, if there is NO serous membrane
between the heart and this fibrous pericardium there will be a
continuous friction and evasion, so to avoid this we have a fluid filled sac
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If we have a fluid filled sac between
two movable structure " part of the sac
will be here and part of the sac will be here" there will be
fluid between them so the structure
can be easily moved without
producing friction.
So, the serous membrane mechanism around movable structures like a
pleura around the lungs is the same as the serous pericardium around
the heart and the same as the serous peritoneum around the abdominal
cavity , BUT what is the difference ? *the sac is elastic by the way *
pleura is only covering one organ " lungs ", same to pericardium that
covering only one organ " heart", however, we stretch the peritoneum
to cover the stomach, small intestine ,large intestine .. etc, so it's more
complicated from any other sac in our body
So, peritoneum here is unique by its complexity, why? because it’s
covering many organs within the abdominal cavity. And here the Greek
name peritoneum comes from: peri= around, toneum = extend ,stretch
the sac to cover the stomach , then small intestine ..etc ,stretched all over
the abdominal cavity .it's very hard to distinguish it's shape cause it isn't a sac
around one organ.
Again, it is a serious membrane made of two continuous layers that
cover the abdominal organs.
It is a sac that made of simple squamous mesothelial cells " mesothelial
mean cells that secret fluid " , this sac is filled with fluid , you close it , you
put it between two movable organ
{ this is stomach and the posterior abdominal wall , between them: Peritoneum }
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So if the two structure move , they will move easily ,because of the fluid
inside the sac.
"that is the simplest way to describe the peritoneum "
Now , when you put this sac between the abdominal wall and the organ
, "EX: between the stomach and posterior abdominal wall" ,part of it will be
facing the wall "muscle + bone" ,the other part will be facing the viscera
, viscus, stomach , organ ,,,,
So the part of the sac lining over /covering / the internal abdominal wall
we name it the parietal layer of the sac and the part covering the
abdominal organ we name it visceral layer," same in pleura (parietal and
visceral)”, DON’T forget that parietal and visceral are one layer:
Note from internet :Viscera: The internal organs of the body, specifically those within the
chest (as the heart or lungs) or abdomen (as the liver, pancreas or intestines). The singular of
"viscera" is "viscus" meaning in Latin "an organ of the body."
Parietal and visceral are one layer remember they are continuous with
each other, the same sac, In between them there is fluid filled space
inside the sac and this called the peritoneal cavity.
So, we have three structure in the peritoneum" look to the cross section “:
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You can easily see here :
This is abdominal wall
These are the kidneys
You can see the Stomach
And Spleen as well.
The blue color"dark+bright"presenting the peritoneal sac , if the peritoneal
sac covering the abdominal wall , here , this will be the parietal layer,,,
Now, once this sac start to reflect to cover over the stomach: become
visceral layer. Cover around the spleen then retains back around the
abdominal wall: becomes parietal again. (follow the picture)
All this space is filled with fluid, peritoneal fluid and we name it:
peritoneal cavity.
So ,remember there are two term here : ( abdominal
cavity , peritoneal cavity ) .....
Abdominal cavity : contain organs + peritoneal cavity
Peritoneal cavity :the space within the peritoneum
only , NO organs " The organ around the sac, the
sac cover those organ", only fluid .
Peritoneal cavity: space between parietal & visceral
layers ,fluid filled  reduce friction
Now, the relation of the abdominal organs to the peritoneum:
Whether covered /invested/ by peritoneum or they are not, depend on
the mobility of the structure and the possibility of friction caused by
other organs.
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Ex: the kidneys they are fixed structure in posterior abdominal wall far
away from the stomach and other movable structures covered anteriorly
by parietal peritoneum , called : retroperitoneal structure , retro = behind
.
The liver is very large organ, that is in contact with the intestine,
stomach , and those are movable organ , I need to cover the liver
Other structure like the spleen: yet it is not a mobile structure, but it is
in a close proximity in to a mobile organ, like the stomach, once the
stomach expands it will touch the spleen, so it must be covered, by
visceral peritoneum : Intraperitoneal structure .
But remember, this miss conceptual name, Intraperitoneal: does not
mean inside the sac, because there is nothing inside the sac ( only fluid ) it
means: completely invested /covered/ by visceral layer of the
peritoneum, here you can reflect without opening the sac and remove it.
Intraperitoneal: completely covered by visceral peritoneum
Retroperitoneal: posterior (behind) the peritoneum ,touched
anteriorly by parietal peritoneum
What about peritoneal cavity?
If you look to cross section there is something to make it much easier
to study the peritoneum, anatomists divide it into two parts:
First: the largest space which extend from the diaphragm up
to reach pelvic cavity, called the greater sac of peritoneal cavity.
second: there is a smaller space of peritoneum that extend behind the
stomach , as we see here, make the stomach Intraperitoneal.
As we said " remember “ the stomach expand and collapse so it is not enough to
keep it anteriorly , also need cover it from behind.
So , the sac cover all the abdominal cavity, and a little bit will extend
behind the stomach
( called the lesser sac) ," purple"
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But remember it's continuous with
the greater sac , and its within the
same peritoneal cavity , but just descriptive
term , No functional separation between them .
So, divide the peritoneal cavity to :
1. Greater sac : main part of peritoneal cavity .
2. Lesser sac (omental bursa): (smaller part) extensional cavity behind
the stomach allows free movement of the stomach, it has 3 recesses:
sup., inf., & splenic *from slide.
The continuation between these two sacs, this gap or this corner,
smaller opening, is: Epiploic foramen or foramen of Winslow, French
anatomist who described it, Jacob Winslow / omental foramen as well “A
rectangle above in the picture " this foramen indicate the continuation
between Greater anteriorly and Lesser sac behind the stomach.
Epiploic foramen = foramen of Winslow = omental foramen
This foramen is NOT a real foramen , just continuation between those
two sac.
If you see the stomach covered here by peritoneum two visceral layer (anteriorly+
posteriorly) " Intraperitoneal" picture above
So , peritoneum cavity :
1/ Anteriorly to the stomach we have : Greater sac / main part .
2/ Behind to the stomach we have : Lesser sac / lesser part .
In between there is foramen of Winslow .
Border of Epiploic foramen:
Now , foramen of Winslow is very important:
Because of so many vital structure around it , Anteriorly to it : Portal
triad ( contain three structure * always together *, going directly into liver )
What are they?
|Page6
Include : 1, Portal vein ‫الوريد البابي‬: the largest ,the most posterior ,which
take blood from the intestine back into the liver to be filtrated, after
filtration within the liver the hepatic vein will drain it in the inferior vena
cava (IVC) to the heart .
2, Hepatic artery: it is the medium size * it is anterior to the left cause
come from left side* , takes oxygenated fresh blood from Aorta to liver
cells for oxygenation.
3, Bile duct: it is anterior to the right , smallest one, and it secret bile
from the liver and gallbladder into the intestine for : emulsification ,
absorption and help in digestion of fat .
All them are anterior to foramen of Winslow : if you want to expand the
foramen of Winslow you can't go and cut anteriorly , because you will
injure these structure .
Posteriorly to foramen of Winslow : large vein going all the way up back
to the heart , which is " inferior vena cava " IVC
Inferior border to that foramen : is the duodenum ( first part of it )
Superiorly : we can see the liver ( caudate lobe " will talk about it later")
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NOW to make the peritoneum much easier to study:
We further subdivide this peritoneum ; because of so many organs .
So we divide the peritoneum into different names depending on the
organs it covers : "remember same sac; continuous"
If it is covering the stomach: Omentum.
If it is covering the small intestine: Mesentry .
If it is covering the large intestine: Mesocolon .
If it is covering the solid organ ( liver , spleen ) :we call it Ligament .
This ligament is two layers of peritoneum, not a true ligament"a dens
fibrous connective tissue " , it's a peritoneal ligament; named ligament to
distinguish different parts, because ligament usually come from solid
organs.
All of these structures: always have to be Double layer of visceral
peritoneum
Why double? Because any organ to be completely covered you need at
least two layer one anteriorly + one posteriorly, if it is covered only from
one side "posteriorly or anteriorly" , it will not be invested , it will be
retroperitoneal. ((Note: if the organ is behind the peritoneum this means that the
organ is covered only anteriorly))
Look here to the stomach ,
|Page8
to become Intraperitoneal it is covered anteriorly and posteriorly with
peritoneum. The one covering posteriorly and the one covering
anteriorly these two visceral layers :called omentum.
we want to start with the stomach, so, this is parietal peritoneum
(posteriorly, anteriorly to kidneys and vertebra) , it's reflected to become here
( see the arrow ) visceral , that is covering behind the stomach , that going
as well as anteriorly to cover the stomach anteriorly .
And this visceral will continue to become parietal ( anteriorly abdominal
wall ) ‫ الخالصة‬,those two visceral layer surrounding the stomach I call them
omentum.
‫ اذا ما عم تفهموا ارجعوا ع الفيديو تبع المحاضرة‬,‫ الدكتور كان يشرح ع الصورة‬,‫مشوا الصورة والحكي سوا‬
And these two visceral layer will leave "split from" the stomach superiorly
(from its lesser curvature) , we called it lesser omentum and the one
going down from the greater curvature of the stomach ,it"s greater
omentum)
Again ,omentum : Broad , always have to be double layer of visceral peritoneum
that connects the stomach to another abdominal structure
organ .
The greater omentum : Leaving from greater curvature ( which divide
into three part ) : see the picture
First / the omentum go up , toward the diaphragm that reflect again to
become parietal peritoneum, called : Gastrophrenic part of greater
|Page9
omentum , Not truly connected " just descriptive " , comes from
stomach and reflects over the diaphragm.
Second /" Gastrosplenic part " from the stomach behind toward the
spleen, it will reflect to cover over the spleen again.
Third / " Gastrocolic part " the largest one, going down from the
stomach (it will go down like an Apron ‫ )مريله‬and reflect back again
toward the transverse colon (cover it),so become transverse Mesocolon.
‫ فبيرجع وبالتالي‬transverse ‫ وبعدين بيذكر انه الزم يلف حويل ال‬, intestine ‫أمام ال‬, ‫بينزل لتحت‬
‫ بصير اسمه‬transverse ‫ لحظة التفافه حول ال‬,‫ طبقات منه إلي هي حكينا عنها المريله‬4 ‫بصير في‬
transverse Mesocolon
They all consist of two layers of peritoneum in exception to the
Gastrocolic part is actually four layers of peritoneum; because it is
descends and ascends again toward the transverse colon.
Now ,In the internal omental Herniation ,what happens here ?
Sometimes part of small intestine within your abdominal cavity will be
looped and move through the foramen of Winslow into the lesser sac
(from the greater sac into the lesser sac) a complicated coiling, once the
intestine gets inside and stuck there, this is called: Internal omental
herniation ( internal : within the abdominal cavity / inside the body) not
external ( to outside), and it's related to omental bursa =the lesser sac.
Part of intestine pass through foramen of Winslow and stuck in lesser
sac , in this case none of the boundaries of the foramen of Winslow can
be incised to reduce the hernia , why ?
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As we said part of intestine come up and inter through that opening into
the lesser sac and stuck there .You can't cut any part of that area to
remove or retrain back the intestine to its origin place ;because :
Anteriorly there is : the portal triad
Posteriorly : IVC
Inferior : the duodenum
Superiorly : the liver
So , how we remove or retrain back this loop of intestine in to the
greater sac from the lesser sac !!
You bring a small knife , cut the greater omentum anteriorly and you
can insert your index finger and push that part outside of
lesser sac.
So, 1st/aspirate the GUT (sometimes with aspiration
only lead to collapse, when it's collapsed it will reduce by
its self ),2nd/ but if it still there you just need to make a
small incision in the greater omentum in Gastrocolic part
(the ant. 2 layer ) and push it with your index finger.
NOW " Lesser omentum" : Post. to it = lesser sac
(the sac covering around the stomach split from the
lesser curvature of the stomach up to the liver) , however it is actually
divided into two part : if look for it from the liver toward the stomach
it's called ligament , if look for it from the stomach toward the liver it's
called omentum.
Lesser omentum: extend from the lesser curvature of stomach and the
first 2 cm of the duodenum to liver . " actually the duodenum is
retroperitonum , but the first two centimeter which are in a close proximity to the
stomach they are covered by part of the lesser omentum"
The two parts of lesser omentum are:
1 , from the liver to the stomach : Hepatogastric ligament.
| P a g e 11
2 , from the liver to the duodenum : Hepatoduodenal ligament , the
last 2 cm (the free edge ) of lesser omentum , actually this edge is
forming the anterior border of foramen of Winslow , so if you bring a
knife and cut the lesser omentum from here you will find 3 structures
" the Portal triad ".
So , they called this 2 layer of visceral peritoneum from the stomach up
to the liver as lesser omentum , but if you look to the free edge of lesser
omentum , that come from the duodenum ,this is Hepatoduodenal
ligament , which contain inside it : the portal triad
Free edge of lesser omentum = Hepatoduodenal ligament = portal triad
Same meaning
| P a g e 12
NOW ,,, The Ligaments: Double layer of peritoneum that is usually
attached to solid organs (liver & spleen)
first one is ,the one that connects the liver with diaphragm and the
abdominal wall ant. (the liver is covered by the peritoneum) that reflects into
two site :1, reflect toward the diaphragm , 2, reflect anteriorly toward
the abdominal wall .
reflection "1+2" in a Falciform
shape ‫ مثل المنجل‬they form the
*Falciform Ligament : the reflection
"attach" of peritoneum from the liver
into ant. abdominal wall and diaphragm.
& end by enclosing ligamentum
teres see the pictures
other ligaments :
*Hepatoduodenal ligament: we study it before .
*Hepatogastric ligament : the remaining part of the lesser omentum ,
same as lesser omentum, different name for the same structure.
2 . Lesser omentum
Ant.
1. Falciform
leg.
3 . Greater omentum
4 . Mesocolon
Post.
please flow the
picture with the
in
5 . Mesentry| P a g e explanation
13
the next page
Lateral view, med sagittal
This is a lateral view, a midsagittal view of abdominal cavity,,, most
important organ will be " the stomach , the most anteriorly is the liver , behind
the stomach we can see the pancreas that's why pancreatitis" inflammation of it "
has the same symptom of gastritis , inferior to the stomach is transverse colon ,
down below we can see many coil of small intestine "
So how to stretch the sac around these organs , first I need to cover the
stomach " most important ", so bring the sac and cover it all around the
stomach , then after covering it , take part around the liver , (this will
form the lesser omentum or hepatogastric ligament) , cover all the liver
then it will reflect over the diaphragm as well as the anterior abdominal
wall , NOW these two reflections of a two double layer of visceral
peritoneum forming the: Falciform ligament , sickle shape .
NOW , from the greater curvature of the stomach descending anteriorly
to all the intestine (large and small) this will be extend much further away
, what happen here is this double layer of peritoneum will reflect up
again , toward the transverse colon ,so NOW this greater omentum is
four layer of peritoneum that will reflect upward , whats located in
between only adipose tissue( not inside peritoneal cavity , just in between the
layers) , this structure is the greater omentum ( Gastrocolic part of greater
omentum ) DO NOT forget it is the only one that have 4 layers of
peritoneum ,the reflection we described it as an apron ‫مريله‬
NOW , these two layers will separate to cover the transverse colon , so I
have 2 layers of visceral peritoneum here will be called transverse
Mesocolon, those two layer once they reach the posterior abdominal
wall , will reflect far away from each other , NOW those become parietal
peritoneum ,one will reach up ( cover anterior part of the pancreas "
retroperitonum ") , close the area there ,forming what we know : the
lesser sac . the other one , descends as parietal peritoneum it will go and
surround to cover the small intestine loops.
double layer ‫الحظوا عم تغطي االلتفافات وبترجع وهكذا وعم تعمل‬
| P a g e 14
These double layer called: Mesentry peritoneum , and it retains to join
the partial layer , this parietal layer will continue to close to form what
we know as : greater sac. Don't forget the sac is : fluid filled
cavity , the omentum : is double layer of peritoneum .
Falciform
L
and both the greater and lesser sac connect with each
other by foramen of Winslow " the arrow on the picture above"
The yellow is adipose tissue between the layer of peritoneum ,
in the empty space , in blue is the greater sac , dark blue is lesser
sac , we can see the foramen of Winslow.
Mesentery & Mesocolon (more detailed):
Mesentry: double layer of peritoneum connects small intestine to
posterior abdominal wall " mesentry of small intestine "
Mesocolon: double layer of peritoneum connects large intestine to
posterior abdominal wall ,*1*transverse mesocolon , *2*sigmoid
mesocolon , *3*mesoappendix
Peritoneal nerve supply : important
Parietal peritoneum ( sensation):
which is in attachment to abdominal wall , so they innervate with the
same innervations of the abdominal wall ,Somatic innervation , " mean
general sensation" ,( not autonomic), so here you can feel pain ,same as
pain in any region.
The innervations is from T 7 to T 12 and first branch of L1
(iliohypogastric) , as well as , "in abdominal wall lecture " .
obturator nerve (in the pelvis ) *from the slides
| P a g e 15
Visceral peritoneum ( only for stretch):
it is covering the organ, so the innervation depend on which organ it
cover ;for example the stomach , there will be innervation to the
omentum," the same as the organ it covers" .
So, in visceral, no pain, it’s lack and refer pain always " only for stretch ",
it's part of autonomic innervation
‫امسك المعدة وقطعها ما حتتوجع بس اذا شديتها حتتوجع‬
NOTE from the internet: partial layer , It receives the same somatic nerve
supply as the region of the abdominal wall that it lines, therefore pain from the
parietal peritoneum is well localized and it is sensitive to pressure, pain, laceration
and temperature.
visceral layer ,has the same nerve supply as the viscera it invests. Unlike the parietal
peritoneum, pain from the visceral peritoneum is poorly localized and is only
sensitive to stretch and chemical irritation. Pain from the visceral peritoneum is
referred to areas of skin (dermatomes) which are supplied by the same sensory
ganglia and spinal cord segments as the nerve fibers innervating the viscera.
Organs Relation to Peritoneum:
*Stomach (Intraperitoneal )
*Duodenum secondary (retroperitoneal, except 1st 2 cm, which is the
free edge of lesser omintum)
*Jejunum & ileum (Intraperitoneal)
*Cecum (??)
When we spoke about the esophagus , it's transmit from striated
muscle into smooth muscle , gradually transform.
So in order to go from Intraperitoneal structure to retroperitoneal
structure there is a gradual transformation, this happen from the small
intestine to the large intestine in cecum region , so as the peritoneum
covering completely ,when reachs the cecum it start to separate from
the cecum ( the cecum is covered but not completely just anteriorly +
laterally ) ,so , it does not has a Mesocolon , cause it partially covered.
and the ascending colon will become retroperitoneum ( not covered ).
| P a g e 16
Note , some books say , it's (secum) covered with peritoneum but does
not have Mesocolon .
*Appendix (Intraperitoneal) :has Mesoappendex , important during
appendectomy procedure you have to ligate and remove the peritoneal
attachment ( catering ) , remove the peritoneal cover first.
*Ascending colon (retroperitoneal)
*Transverse colon (Intraperitoneal)
*Descending colon (retroperitoneal)
*Sigmoid colon (Intraperitoneal)
*Rectum: within the pelvis not in the abdominal cavity
it will pass a way down in pelvis , 1st upper third partial
covered (ant. & lat.) , the 2nd middle third just anteriorly ,the 3rd lower
third below the peritoneal cavity , it is in pelvic cavity ,so it is not
covered by the peritoneum (subpertoneal) below
*Liver (Intraperitoneal with exception):
Cover by peritoneum except over three area
1, Bare area of the liver .
2, Where the portal triad enter and leave ,because if it’s covered by the
peritoneum ,these portal triad can't get into the liver , this area called
"Portal hepatics " or " Helium of the liver " *any organ in the body have the
Helium " like: lungs, kidneys " , helium means the gate ‫ بوابة‬where the vital structure
come and leave ( VAN) and other important structure related to that organ.
3, " bed of the gallbladder" , where the gallbladder is resetting , because
once there is a gallbladder over the liver ,the peritoneum can't become
in between them , so, it will cover the gallbladder , but if you remove the
gallbladder you can notice the rough surface of the liver down it ‫مكان‬
‫المرارة‬
Bare area
| P a g e 17
*Pancreas: "Retroperitoneal”, except for the tail which is Intraperitoneal
*Spleen: "Intraperitoneal"
*Kidneys: "primary Retroperitoneal"
*abdominal part of the esophagus : 1.25 cm penetrating the diaphragm
to the stomach is ‫واجب حسب ما لقيته بالنت تحت‬
: ‫ انه الزم نعرفهم فحسب النت‬6‫ وبرضو حكى عنهم بالمحاضرة ال‬, ‫طلب الدكتور واجب‬
NOTE: we have 4 structure which consider primary retroperitoneal, as
well as 4 structure are secondary retroperitoneal


Primarily retroperitoneal, meaning the structures were retroperitoneal during
the entirety of development:
o urinary
 adrenal glands
 kidneys
 ureter
o circulatory
 aorta
 inferior vena cava
o digestive
 esophagus (thoracic part, part inside abdominal cavity is
Intraperitoneal)
 rectum (middle third only)
Secondarily retroperitoneal, meaning the structures initially were suspended in
mesentery and later migrated behind the peritoneum during development:
o the head, neck, and body of the pancreas (but not the tail)
o the duodenum, except for the proximal first segment, which is
Intraperitoneal
o ascending and descending portions of the colon (but not the transverse
colon, sigmoid or the cecum)
_________________________________________________________
!! ‫يحوز النصر من يصبر أكثر‬
| P a g e 18
1. Which of the following is correct
a. The portal triad is anterior to the foramen of winslow
Answer: a
2. The 4-layered part of the peritoneum is:
a. Gastrocolic ligament
b. Lesser omentum
c. Gastrophrenic ligament
d. Gastrosplenic ligament
Answer: a
3. Which of these is retro-peritoneal
a. Duodenum, Ascending colon, & Abdominal esophagus
4. The foramen epiploica (omental foramen) is bounded by the followings,
EXCEPT the :
-Right kidney.
5. Developmentally , greater omentum is derived from:
- Dorsal mesogastrium
___________________________________________________________
All the slides are included , record A + B ,you can see extra picture for
more understand, any mistake put it in correction zone
,sorry about any mistake .
Recommended Textbooks
Clinical Anatomy by Region.
Author: Richard S. Snell.
Publisher: Wolters Kluwer/Lippincott Williams &
Wilkins
Principles of Human Anatomy
Authors: Gerard Tortora, Mark Nielsen
Publisher: John Wiley & Sons, Inc.
Grant’s Atlas of Anatomy
Authors: Anne Agur, Arthur Dalley
Publisher: Wolters Kluwer/Lippincott Williams &
Wilkins
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