Changes

==Overview==

==Overview==

The '''abomasum''' is the fourth chamber in the ruminant. It functions similarily to the [[Monogastric Stomach - Anatomy & Physiology|carnivore stomach]] as it is glandular and functions to digest food chemically, rather than mechanically or by fermentation like the other 3 chambers of the ruminant stomach.

The '''abomasum''' is the fourth chamber in the ruminant. It functions similarly to the [[Monogastric Stomach - Anatomy & Physiology|carnivore stomach]] as it is glandular and digests food chemically, rather than mechanically or by fermentation like the other 3 chambers of the ruminant stomach.

The '''abomasum''' differs in its position within the abdomen, depending on fullness of the other chambers of the stomach, intrinsic abomasonal activity, contractions of the '''[[Rumen - Anatomy & Physiology|rumen]]''' and '''[[Reticulum - Anatomy & Physiology|reticulum]]''' (to which it is attached) and by age and pregnancy.

The '''abomasum''' differs in its position within the abdomen, depending on fullness of the other chambers of the stomach, intrinsic abomasonal activity, contractions of the '''[[Rumen - Anatomy & Physiology|rumen]]''' and '''[[Reticulum - Anatomy & Physiology|reticulum]]''' (to which it is attached) and by age and pregnancy status.

[[Displaced Abomasum|Displacement of the abomasum]] to the left or to the right is a common disorder affecting dairy cows due to high concentrate feed.

[[Displaced Abomasum|Displacement of the abomasum]] to the left or to the right is a common disorder affecting dairy cows due to high concentrate feed.

[[Image:Abomasum Anatomy Sheep.jpg|thumb|right|250px|Abomasum Anatomy (Sheep) - Copyright RVC 2008]]

[[Image:Abomasum Anatomy Sheep.jpg|thumb|right|250px|Abomasum Anatomy (Sheep) - Copyright RVC 2008]]

The '''abomasum''' lies upon the abdominal floor. The cranial part is split into the '''pylorus''' and '''body'''. There is also a caudal part. It is covered by the '''lesser omentum'''. It has 15-20 folds inside. The '''torus''' is at the pyloric exit. The outflow is fairly constant. There is motility at the '''pylorus''' (peristalsis). There is some control at the '''pyloric sphincter'''. The abomasum is large in newborn animals. The proximal ends of the abomasal folds forms a plug preventing reflux into the '''[[Omasum - Anatomy & Physiology|omasum]]'''. It has thin walls and a serousa covering.

The '''abomasum''' lies upon the abdominal floor. The cranial part is split into the '''pylorus''' and '''body'''. There is also a caudal part. It is covered by the '''lesser omentum'''. It has 15-20 folds inside. The '''torus''' is at the pyloric exit. The outflow is fairly constant. There is motility at the '''pylorus''' (peristalsis) and some control at the '''pyloric sphincter'''. The abomasum is large in newborn animals. The proximal ends of the abomasal folds form a plug preventing reflux into the '''[[Omasum - Anatomy & Physiology|omasum]]'''. It has thin walls and a serosa covering.

==Function==

==Function==

The function of the abomasum is the chemical breakdown of food. It secretes hydrochloric acid and pepsinogen. It has some intrinsic motility. Impaired motility can cause distension. The movements are slow, contractions occur first in the proximal part and are more forceful at the pyloric part.

The function of the abomasum is the chemical breakdown of food. It secretes '''hydrochloric acid''' and '''pepsinogen'''. It has some intrinsic motility. Impaired motility can cause distension. The movements are slow, contractions occur first in the proximal part and are more forceful at the pyloric part.

==Vasculature==

==Vasculature==

The vasculature of the abomasum includes the '''cranial mesenteric artery''', the '''celiac artery''' and the '''left gastric''' and '''left gasrtoepiploic''' arteries.

The vasculature of the abomasum includes the '''cranial mesenteric artery''', the '''celiac artery''' and the '''left gastric''' and '''left gastroepiploic''' arteries.

==Innervation==

==Innervation==

[[Image:Abomasum Histology Sheep.jpg|thumb|right|150px|Abomasum Histology (Sheep) - Copyright RVC 2008]]

[[Image:Abomasum Histology Sheep.jpg|thumb|right|150px|Abomasum Histology (Sheep) - Copyright RVC 2008]]

*Simple columnar epithelium

The abomasum has a simple columnar epithelium. There are 3 layers of '''''tunica muscularis''''' - inner oblique, middle circular and outer longitudinal. The '''''lamina muscularis''''' is thicker and has 3 separate layers.

Gastric glands are present in the '''''lamina propria''''' of the mucosal layer in the pyloric region (lighter part). The abomasum is heavily coated by mucous for protection. The submucosa contains loose connective tissue, many blood vessels and unilocular adipocytes. The coiled glands in the ''lamina propria'' open into deep gastric pits. The inner mucosa is pink. '''Rugae''' are present in the pyloric region and a '''torus''' (large swelling) is present at the pyloric passage to narrow the lumen. The dark mucosa of the fundus and body contains peptic glands.

 

 

*Gastric glands in lamina propria of mucosal layer in pyloric region (lighter part)

 

*Heavily coated by mucous for protection

 

*Submucosa contains loose connective tissue, many blood vessels and unilocular adipocytes

 

 

*Coiled glands in lamina propria opening into gastric pits

 

*Pink inner mucosa

 

*Rugae are present in the pyloric region

 

*Torus (large swelling) is present at the pyloric passage to narrow the lumen

 

*Dark mucosa of fundus and body contain peptic glands

==Species Differences==

==Species Differences==

==Links==

==Links==

'''Click here for [[Rumen - Anatomy & Physiology|Rumen - Anatomy & Physiology]]'''

'''Click here for [[Rumen - Anatomy & Physiology|Rumen - Anatomy & Physiology]]'''

'''Click here for [[Omasum - Anatomy & Physiology|Omasum - Anatomy & Physiology]]'''

'''Click here for [[Omasum - Anatomy & Physiology|Omasum - Anatomy & Physiology]]'''

 

<rss max="10" highlight="none">https://www.thewebinarvet.com/gastroenterology-and-nutrition/webinars/feed</rss>

 

 

 

4.[http://stream2.rvc.ac.uk/Frean/sheep/LeftSideTopography.mp4 Left sided topography of the Ovine Abdomen and Thorax]

 

 

6.[http://stream2.rvc.ac.uk/Frean/sheep/RuminantStomachStructure.mp4 Structure of the ruminant forestomachs]

 

 

[[Category:Stomach - Anatomy & Physiology]]

[[Category:Stomach - Anatomy & Physiology]]

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[[Category:A&P Done]]

[[Category:Alimentary Anatomy - Cattle]]