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==Introduction==

==Introduction==

The duodenum is the proximal part of the small intestine and extends from the pylorus of the [[Monogastric Stomach - Anatomy & Physiology|stomach]] to the [[Jejunum - Anatomy & Physiology|jejunum]]. It has descending and ascending portions and both portions have digestive and absorptive functions.

The duodenum is the proximal part of the small intestine and extends from the '''pylorus''' of the [[Monogastric Stomach - Anatomy & Physiology|stomach]] to the '''[[Jejunum - Anatomy & Physiology|jejunum]]'''. It has descending and ascending portions and both portions have digestive and absorptive functions.

==Structure==

==Structure==

*The descending duodenum passes out of the pylorus of the [[Monogastric Stomach - Anatomy & Physiology|stomach]] (on the right side of the abdomen) and has a sigmoid flexure. It passes towards the right abdominal wall and rises dorsally. In its passage it is related dorsally to the right lobe of the [[Pancreas - Anatomy & Physiology|pancreas]], ventrally to the [[Jejunum - Anatomy & Physiology|jejunum]] and medially to the ascending [[Colon - Anatomy & Physiology|colon]] and [[Caecum - Anatomy & Physiology|caecum]].  

 

**At a point between the right [[Macroscopic Renal Anatomy - Anatomy & Physiology#Common Anatomy|kidney]] and pelvic inlet it turns medially and cranially around the root of the mesentery to become the ascending duodenum. The point of turn is called the ''caudal flexure'' of the duodenum.

The descending duodenum passes out of the '''pylorus''' of the [[Monogastric Stomach - Anatomy & Physiology|stomach]] (on the right side of the abdomen) and has a sigmoid flexure. It passes towards the right abdominal wall and rises dorsally. In its passage, it is related dorsally to the right lobe of the [[Pancreas - Anatomy & Physiology|pancreas]], ventrally to the [[Jejunum - Anatomy & Physiology|jejunum]] and medially to the ascending [[Colon - Anatomy & Physiology|colon]] and [[Caecum - Anatomy & Physiology|caecum]].  

**The ascending duodenum is shorter and bends ventrally to enter the mesentery and becomes the [[Jejunum - Anatomy & Physiology|jejunum]].

At a point between the right [[Macroscopic Renal Anatomy - Anatomy & Physiology#Common Anatomy|kidney]] and pelvic inlet, it turns medially and cranially around the root of the mesentery to become the ascending duodenum. The point of turn is called the ''caudal flexure'' of the duodenum.

*Mesoduodenum attaches the duodenum to the dorsal abdominal wall.  

The ascending duodenum is shorter and bends ventrally to enter the mesentery and becomes the [[Jejunum - Anatomy & Physiology|jejunum]]. The '''mesoduodenum''' attaches the duodenum to the dorsal abdominal wall. Within the mesoduodenum is the right lobe of the [[Pancreas - Anatomy & Physiology|pancreas]]. The pancreatic and bile ducts open into the duodenum. The bile duct and one of the pancreatic ducts discharge into the proximal part of the duodenum by separate ''major duodenal papillae''. The second pancreatic duct discharges a little more distally on a smaller papilla. The cranial part of the descending duodenum is attached to the [[Liver - Anatomy & Physiology|liver]] by the '''hepatoduodenal ligament'''. This is a remnant of the [[Monogastric Stomach - Anatomy & Physiology|ventral mesogastrium]] in the embryo. The bile duct runs within the '''hepatoduodenal ligament'''.

**Within the mesoduodenum is the right lobe of the [[Pancreas - Anatomy & Physiology|pancreas]].

*The pancreatic and bile ducts open into the duodenum.

**The bile duct and one of the pancreatic ducts discharge into the proximal part of the duodenum by separate ''major duodenal papillae''.

**The second pancreatic duct discharges a little more distally on a smaller papilla.

*The cranial part of the descending duodenum is attached to the [[Liver - Anatomy & Physiology|liver]] by the '''hepatoduodenal ligament'''. This is a remnant of the [[Monogastric Stomach - Anatomy & Physiology|ventral mesogastrium]] in the embryo.

**The bile duct runs within the hepatoduodenal ligament.

==Vasculature==

==Vasculature==

*The duodenum recieves blood from:

The duodenum recieves blood from the '''coeliac artery''' and the '''cranial mesenteric artery'''. Both are branches of the aorta. The '''cranial mesenteric vein''' drains blood from the duodenum into the '''portal vein'''. This blood, carrying the products of digestion, enters the [[Liver - Anatomy & Physiology|liver]].

**Coeliac artery

**Cranial mesenteric artery

*Both are branches of the aorta.

*The cranial mesenteric vein drains blood from the duodenum into the portal vein.

**This blood, carrying the products of digestion, enters the [[Liver - Anatomy & Physiology|liver]].

==Species Differences==

==Species Differences==

===Canine===

===Canine===

*Duodenum is about 25cm long.

The duodenum is about 25cm long in canine species. The mesoduodenum is relatively long.

*Mesoduodenum is relatively long.

===Equine===

===Equine===

[[Image:Section of duodenum from horse.JPG|thumb|right|150px|Section of equine duodenum- © RVC 2008]]

[[Image:Section of duodenum from horse.JPG|thumb|right|250px|Section of equine duodenum- © RVC 2008]]

*Mesoduodenum is relatively short, so the duodenum is closely tethered in a constant position.

The mesoduodenum is relatively short, so the duodenum is closely tethered in a constant position. The descending duodenum is attached to the base of the [[Caecum - Anatomy & Physiology|caecum]]. The descending duodenum runs caudally beneath the [[Liver - Anatomy & Physiology|liver]] to the caudal pole of the right [[Urinary System - Anatomy & Physiology|kidney]] where it has it's caudal flexure to become the ascending duodenum.

*Descending duodenum is attached to the base of the [[Caecum - Anatomy & Physiology|caecum]].

*Descending duodenum runs caudally beneath the [[Liver - Anatomy & Physiology|liver]] to the caudal pole of the right [[Urinary System - Anatomy & Physiology|kidney]] where it has it's caudal flexure to become the ascending duodenum.

===Ruminant===

===Ruminant===

*Mesoduodenum is relatively short.

The mesoduodenum is relatively short. The first part of the descending duodenum rises almost vertically within the ribcage, in close apposition to the [[Liver - Anatomy & Physiology|liver]]. It turns level with the tuber coxae. The first part of the duodenum is attached to the [[Liver - Anatomy & Physiology|liver]] by the lesser omentum. The descending duodenum also provides attachment for the superficial and deep sheets of the greater omentum.

*The first part of the descending duodenum rises almost vertically within the ribcage, in close apposition to the [[Liver - Anatomy & Physiology|liver]].

*It turns level with the tuber coxae.

*The first part of the duodenum is attached to the [[Liver - Anatomy & Physiology|liver]] by the lesser omentum.

*Descending duodenum also provides attachment for the superficial and deep sheets of the greater omentum.

===Porcine===

===Porcine===

*Small intestine is comparable to the dog.

The small intestine is comparable to the dog. The mesoduodenum is relatively long.

*Mesoduodenum is relatively long.

 

 

 

 

*[[Duodenum - Anatomy & Physiology - Flashcards| Duodenum Flashcards]]

2.[http://stream2.rvc.ac.uk/Frean/Pony/left_topography.mp4 Left Sided topography of the Equine abdomen]

4.[http://stream2.rvc.ac.uk/Frean/sheep/RightSideTopography.mp4 Right sided topography of the Ovine Abdomen]

*[http://stream2.rvc.ac.uk/Anatomy/canine/Pot0036.mp4 Pot 36 The Canine Abdomen]

*[http://stream2.rvc.ac.uk/Frean/sheep/RightSideTopography.mp4 Right sided topography of the Ovine Abdomen]

[[Category:Small Intestine - Anatomy & Physiology]]

[[Category:Small Intestine - Anatomy & Physiology]]

[[Category:To Do - A&P]]

[[Category:To Do - AimeeHicks]]