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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 |Page1 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 } |Page2 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 “: |Page3 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. |Page4 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" |Page5 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") |Page7 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 ? | P a g e 11 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 | P a g e 19