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Gross anatomy of Duodenum with blood supply.


Small Intestine





Small Intestine is the most longest part of GI tract, measuring upto 6-7 metre long when measured outside of the body





Another interesting thing about SI is that it's lumen width keep on decreasing as we move toward its end





Extent :- SI extends from the Pyloric orifice of stomach to Ileocaecal fold.





Parts :- SI is divided into 3 parts, the division is on the basis of their physiological activities and the 3 parts are





  • Duodenum
  • Jeujenum
  • Ileum




Duodenum





In this article, we will be focusing on just the Duodenum part only.





Length of Duodenum :- Duodenum measures mealy about 20-25 cm long.





It is a C shaped structure, present on the upper side of umbilicus (Navel).





Extent :- It extends from the Pyloric orifice to Duodenojejunal flexure.





Retroperitoneal or Intraperitoneal? :- Interestingly the Duodenum is both.





The initial portion of Duodenum which is close the Pyloric part of stomach is actually intraperitoneal as it has an ligament which connects it to liver named - "Heap to-duodenal ligament" which is nothing but a part of lesser omentum, so that portion which has this ligament is "Intraperitoneal" while the left whole portion is Retroperitoneal.





Parts of Duodenum.





There are 4 parts of Duodenum





(Yeah, it is awkward that small intestine has 3 parts but Duodenum has 4 parts) 😂





So I want an complete attention and focus from now on specially.





To make things easier, we will follow a format while reading every part of Duodenum





We will first learn about Extent then we will talk out relation and finally we will talk about other features of that part. This will be followed now till end of article.





PARTS :-





  • Superior part
  • Descending part
  • Inferior part
  • Ascending part




Here is a diagram from grays anatomy :-









Now I want you to read the below text and observe the mentioned details from the diagram above, otherwise you wil not be able to understand the Duodenum.





Superior Duodenum





Extent:- It extends from "Pyloric orifice to the Neck of Gall bladder" .





Relations:- It is present adjacent to pancreas





On Posterior side there is :-





  • Gastroduodenal artery
  • Inferior vena cava
  • Bile duct
  • Portal Vein




On its left side :- Body of "L1 Vertebrae".





Or you can it is present just right to body of L1 vertebrae.





Clinical Relevance :-





The initial part of superior part of Duodenum which is just next to Pyloric orifice of stomach is very wide in its diameter, it is also known as "Duodenal Cap" or "Ampulla"





This part is the most common location of Duodenum ulcers.





Note:- Don't forgot to observe the text details from the above diagram





Descending Duodenum





Extent :- From the Neck of Gall bladder to lower border of L3 Vertebrae





Relations :-





Posteriorly to this part is :- Right kidney.





Anteriorly to this is :- Transverse colon.





On left side is :- Head of Pancreas.





Extra points :-





You might be knowing that common Bile and accessory pancreatic duct opens into Duodenum, but at which part of Duodenum?





Descending Duodenum is that part.





There are two opening sites in this part :-





Minor Duodenal papilla and Major Duodenal papilla





The Minor Duodenal papilla actually recieves the - "Accessory pancreatic duct" also known as Duct of Santorini





The Major Duodenal papilla actually recieves the Common Bile duct which is formed from the combination of bile duct from Gall bladder (Which was posterior to the Superior Duodenum) and pancreatic duct from Pancreas. It is also known as "Papilla of Vater".





Note :- Duct of Santorini is not functional in many people that's why it is often known as Accessory pancreatic duct





Majority of it will be discussed in the Embryology but for a quick review, just read this





The Development of Pancreas actually occurs in form of buds :- A dorsal bud and A ventral bud, in initial stages each of these buds has their own duct connection to Duodenum, but as development progress and foregut rotates so does the buds of Pancreas and this result in formation of a common Bile duct and duct of dorsal bud get limited it it's work and is known as Duct of Santorini or Accessory Pancreatic Duct.





See the below image for a more clear understanding.









Boundary of Forgut anf Midgut :- actually is just below the Major Duodenal papilla, in an unstrict sense you can say that above the major duodenal papilla is :- Foregut and below it is :- Midgut.





Inferior Duodenum





So from now on we have entered in Midgut, as we have passed the Major duodenal papilla.





This portion of Duodenum has a very ill defined extent.





Relations :-





On Posterior side :- Vena cava, Aorta





On Anterior side :- Superior mesenteric artery (Major vessel for supply to Midgut)





Note :- I have not mentioned right, left in this relation part and in many others above as there is no significant relation over there.





Ascending Duodenum





Extent :- From the ending part of inferior Duodenum which is roughly defined to the Duodenojejunal Flexure which is present at the level of upper surface L2 vertebrae





Relations :-





No significant relations.





Special points :- This part ends at Duodenojejunal flexure





This duodenojejunal flexure is surrounded by a fold of peritoneum containing muscle fibers called the suspensory muscle (ligament) of duodenum (ligament of Treitz).





You must remember that ligament.





Blood supply of Duodenum.





Duodenum is both under Foregut and Midgut, that's why it is perfused by branches of both "Celiac trunk" and "Superior mesentric artery"





For those who does not know, let me tell you that Celiac trunk - a major division from abdominal aorta is responsible for the blood supply to Foregut part





"Superior mesentric artery" which is an another big vessel arising from abdominal aorta is responsible for blood supply of Midgut.





Blood supply of Duodenum:-





If you have not read my article on blood supply of stomach than I recommend you to go and read it, if you are done with blood supply of stomach than let us proceed further :-





A branch of common hepatic artery named "Gastroduodenal artery" is responsible for the blood supply to stomach and Duodenum, as suggested by his name.





Branches of Gastroduodenal artery :-





  • Duodenal branches
  • Superior pancreaticDuodenal artery
  • Right gastroepiploic artery




See in the below diagram :-









Now see the Duodenal branches is actually responsible for direct perfusion to Duodenum as you Can see in above image





But the Superior pancreaticDuodenal artery divides into two parts:- Anterior superior pancreaticDuodenal artery and posterior superior pancreaticDuodenal artery, which runs on Anterior and posterior surfaces of Descending Duodenum respectively and perfuse them.





See in above image carefully.





Now let's come to the contribution by Superior mesentric artery to the perfusion of Midgut Duodenum.





Superior mesentric artery after arising from abdominal aorta ascends and give different branches and one among them is "Inferior pancreaticDuodenal artery" which also divides into "Anterior inferior pancreaticDuodenal artery" and "Posterior inferior pancreaticDuodenal artery" as it ascends and they finally anastomose with their corresponding sides of branches of Superior pancreaticDuodenal artery.





So the anterior superior pancreaticDuodenal artery anastomose with the anterior inferior pancreatic Duodenal artery and the posterior superior pancreaticDuodenal artery anastomose with the posterior inferior pancreaticDuodenal artery.





Observe all the above mentioned points from the diagram.





For examination part you can read the blood supply my od Duodenum from below.









That's all from my side.





Signing off...





Bhavesh saini.


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