بسم هللا الرحمن الرحيم

Transcription

1 بسم هللا الرحمن الرحيم **As we remember from the last lecture: The arterial supply which comes from the single branches of the aorta drains in the portal vein (venous drainage of the gut = portal vein). Now we will start with the portal vein.. as usual we want to know (beginning, course, end and tributaries just clinical importance of them ) 1.Begining : it begins as the union of splenic vein and the superior mesenteric vein (from the intestine). Note : the inferior mesenteric vein drains the blood from the descending colon and it joins the splenic vein. 2. Course: it enters the liver from an opening which called porta hepatis. Be aware: it s important to know the site of formation of the portal vein let us remember the C shaped organ (duodenum) in its concavity we find the pancreas which divides into head, neck, body and tail. The portal vein forms behind the neck of the pancreas. 1

2 So the portal vein forms posterior to the neck of the pancreas as the union of the superior mesenteric and splenic veins 3. End: it enters the liver and divides to give its branches 4. Clinical importance: the portal circulation is a separate circulation which takes the venous drainage of the gut but it s not completely separate from the systemic venous circulation of the body, they are united at 3 regions (anastomosis between the portal and the systemic venous circulation portosystemic anastomosis ): 1. the union between the upper part of the stomach and the lower part of the esophagus (at the beginning of the portal) 2. at the anal canal (the end of the gut, the end of the portal) 3. around the umbilicus (superficial veins at the anterior abdominal wall) A short story: If we have a disease in the liver either we can fix it or not it leads at the end to liver cirrhosis (that means we have a fibrous tissue deposited in the passage ways between the cells which leads these passages to close or to narrow ), then the portal vein when it empties its contents it will find it difficult to do that and the blood will accumulate in the portal circulation, by the time the pressure in the portal circulation (portal hypertension) will increase but the veins will not rapture it will compress at the sites of the anastomosis because of the low pressure there (portosystemic anastomosis: the 3 regions that we have already mentioned) this leads these veins to be: 1. Filled with blood. 2. Dilated(because the wall does not contain muscles it can dilate easily). 3.turtous. these 3 signs are signs of the varices: 1. esophageal varices. 2. The veins that are at the anal canal will cause hemorrhoids. 3. The veins that are radiating around the umbilicus will cause caput medusa (you can see that like the sun under the skin with a bluish color). 2

3 when I found these 3 signs I know that the patient has portal hypertension which is a result of liver cirrhosis. The danger of these things is that the walls of the veins are very thin with the increased abdominal pressure they will rapture which causes bleeding until death, and usually who dies from that he will suffer from hematemesis (vomiting of blood) because of the rapture of the esophageal varices. **Why does alcohol causes cirrhosis?? Because it cause inflammation in the liver and this inflammation cannot be treated so actually around 100% it will lead to cirrhosis, also any inflammation in the body we did not treat, we treat in a wrong way or we take antibiotics for a short period this inflammation will disappear and convert into fibrous tissue. Now stop for a second and take a deep breath. we have to know some things about the liver, pancreas and spleen then we will finish this course, so let us continue The liver: 1 st. The largest gland all over the body which secretes the bile (it is NOT the gallbladder it is the liver which secretes the bile), the bile will be concentrated in the gallbladder which will be secreted from the biliary system. 3

4 2 nd. the site of the liver: it is located in the first row of the abdominal nine regions (right hypochondrium, epigastric and a part of the left hypochondrium). 3 rd. the orientation of the liver: it is pyramidal in shape, it is lying on its side (like the heart),and has: apex (directed to the left side), base(directed to the right) & 4 surfaces (according to their position or direction: superior, inferior, anterior and posterior). **How to differentiate between the posterior surface and the inferior surface?? At the posterior aspect we have an opening which called porta hepatis (where we observe that the vessels enter and exit the liver) we put there a horizontal line, above this line we find the posterior surface and below it there is the inferior surface (this is the best way to differentiate between them). 4 th. the lobes of the liver: it is composed of 2 large lobes and 2 small lobes. the large lobes: right lobe at the right side and left smaller lobe. **How to differentiate between the right site and the left side?? We look for a complete circle around the liver(it is obvious on the 4 surfaces) and we put our hands on it then everything at the right side is a part of the right lobe also everything at the left side is a part of the left lobe. In this circle at the superior and anterior surfaces we find a ligament, using the line of attachment of this ligament we can differentiate between the right lobe and the left lobe at the superior and anterior surfaces. 4

5 From where did this ligament arise?? It arose from the peritoneum (sac of the abdomen) which gave fold (ligament) that attach to the liver to fix it on the anterior abdominal wall. Because this ligament is crescent in shape we call it falciform ligament. Now, from posterior and inferior surfaces: at this aspect of the liver we find 2 groves one above the line that we have already mentioned in the posterior surface and one below in the inferior surface, in the first groove (above) we will find a ligament called ligamentum venosum and in the other one (below) we will find a ligament called ligamentum teres A way to memorize them: وفق.. venosum تتح.. teres From where did these ligament arise?? When we was at the intrauterine life we used to have umbilical artery and umbilical vein which is important for the exchange of blood between the mother and the fetus and after delivery we do not need that, we breath and we can oxygenate our blood, then they will experience obliteration and fibrosis, then they will form these ligaments as remnants from those vessels. 5 th. relations of the liver: A. Superior surface: 1. Diaphragm which separates the liver from the following organs: 5

6 2. Right lung and right pleura. 3. Left lung and left pleura. 4. Heart and pericardium. B. Anterior surface: we will divide it into two parts: 1. Upper part related to the diaphragm. 2. Lower part related to the anterior abdominal wall muscles (external oblique, internal oblique, transversus abdominis and rectus abdominis) C. Right side (roughly at the mid axillary line): 1. Related directly to the diaphragm which separates the liver from the following structures: 2. The ribs from the 7 th to the 11 th rib. 3. Right lung and right pleura. D. The most important surfaces are the posterior and the inferior because the posterior lies on the posterior abdominal wall and the inferior is related to the viscera (here we will learn the parts + the boundaries and we will start from right to the left): 6

7 1. First of all the dull area (not glistering like the others) we call it the bare area of the liver (not covered by peritoneum). Remember: the liver is one of the organs that will grow largely and it will be completely covered by the peritoneum except one area (the bare area). 2. When we proceed to the left side we find a groove for the great vein that lies on the posterior abdominal wall (inferior vena cava). 3. Then we find the third lobe of the liver (caudate lobe). Boundaries of this lobe: a. at the right side: inferior vena cava. b. at the left side: fissure for ligamentum venosum. c. superiorly: upper surface of the liver. d. inferiorly: porta hepatis. 4. Then we proceed to the left lobe which lies on the stomach that means we have a gastric impression on the liver at this site (back of the left lobe). 5. Then we will go downward then we will return to the right side crossing the ligamentum teres then we will find the 4 th lobe of the liver (quadrate lobe). Boundaries of this lobe: a. at the left side: ligamintum teres. b. at the right side: gallbladder. c. upwards: porta hepatis. d. downwards: inferior border of the liver. Remember: the stomach ends at the pylorus to continue as the duodenum. So the first part of duodenum is related to the upper part of the quadrate lobe. also the transverse colon is located there.. So it s related to the lower part of this lobe. 6. Then we proceed to reach the gallbladder which consist of three parts: Fundus (the head), body (the largest part), neck (the constriction). 7. Then we proceed to reach the colic impression which is made by the right colic flexure (hepatic flexure; because it is related to the liver) 7

8 Remember: the ascending colon turns to the left and continues as the transverse colon which causes the formation of the right colic flexure. 8. Then we go upwards to reach another impression (renal impression) which lies on the right kidney and the right suprarenal. 6 th. An important note: the portal vein and the hepatic artery, when they enters the liver they will divide into two branches one for the right lobe and the other is for the left lobe. BUT we have an exception : the caudate and the quadrate lobe are anatomically part of the right lobe but functionally they are related to the left side (they take blood supply from the left hepatic artery and the left portal vein and they drains in the left hepatic vein also anything they secrete goes to the left side) 7 th. The porta hepatis consists of: 1. Bile duct (the most anterior in position and carries the bile that is secreted from the liver). 2. Intermediate in position we have the hepatic artery which is a branch from the celiac trunk (it s derived from the foregut). 3. The most posterior in position is the portal vein. 8 th. the blood supply of the liver (the portal vein and the hepatic artery): 1. The portal vein provides the liver with 75%-80% of its needs (most important) 2. The hepatic artery provides the liver with oxygen. 8

9 As they enter the liver they divides into right and left branches then they divides more and more, the liver then takes its needs and the other things drains in the hepatic vein which will drain in the inferior vena cava (the last tributaries to the inferior vena cava before it enters the central tendon to drain in the heart). 9 th. the biliary system: The bile is secreted by the liver cells then it will continue into two ducts (right hepatic duct from the right lobe and left hepatic duct from the left lobe), both hepatic ducts unites to form the common hepatic duct (which sends the bile to the gallbladder to be concentrated there) then the bile will leave the fundus, body and neck through the cystic duct which unite with the common hepatic duct to form the common bile duct which also unite with the pancreatic duct to enter the duodenum from the postromedial aspect at the midpoint of the second part. قال اإلمام الشافعي رحمه هللا : ولما قسى قلبي وضاقت مذاهبي...جعلت الرجا مني لعفوك سلما تعاظمني ذنبي فلما قرنته بعفوك...ربي كان عفوك أعظما وما زلت ذا عفو عن الذنب لم تزل...تجود وتعفو منة وتكرما إليك إله الخلق أرفع رغبتي... وإن كنت يا ذا المن والجود مجرما 9 وأخيرا أعتذر عن اي اخطاء وردت اثن اء الكتابة فالخطأ من طبيعة البشر