Ruminant GI Tract Flashcards
Approximately how much space in the abdominal cavity does the rumen and reticulum take up in a cow?
Rumen: 80%
Reticulum: 5%
What is the difference between a concentrate selector and a grass-roughage eater?
Concentrate selectors eat faster growing plants that are easier to digest because they have more frequent and faster rumen contractions.
Grass-roughage eaters eat tougher foods that take longer to digest
What is the function of the esophageal groove?
It allows liquid to bypass the rumen and go straight into the reticulum. This is important in neonates who drink milk and adults that are dehydrated
What is the insula ruminis located between?
The longitudinal fold
What part of the rumen does a bolus of food first go into from the esophagus?
Atrium ruminis
List all the sacs within the cow rumen
Cranial sac
Dorsal sac
Ventral sac
Caudodorsal blind sac
Caudoventral blind sac
Which pillars (folds) separate the caudodorsal and caudoventral blind sacs?
Dorsal and ventral coronary pillars respectively. The caudal fold runs between the sacs
Which sac is greatly reduced in sheep?
Caudodorsal blind sac
What is the structure that divides the cranial sac of the rumen and the reticulum called?
Ruminoreticular groove
Which structures are located on the left and right side of the cow?
Rumen - left
Reticulum - left
Omasum - right
Abomasum - mostly right/ventral midline
What type of epithelium lines the ruminant GI tract?
Stratified squamous epithelium
What is the function of papillae in the rumen?
Greater surface area for efficient digestion
What can happen in the reticulum if the cow eats wire or nails?
The foreign objects can become trapped within the deep pockets that line the reticulum and contractions can cause perforations that lead to TRP (traumatic reticular peritonitis)
How much abdominal volume does the omasum take up in roughage eaters? What about concentrate selectors?
Roughage eaters - 8%
Concentrate selectors - 4%
Where do the folds within the omasum originate?
From the greater curvature
What is the structure called that connects the reticulum and the omasum?
Reticulo-omasal orifice
What does the omasal canal connect to?
Omasoabomasal orifice
What is the abomasum?
The glandular stomach (true stomach) that secretes digestive enzymes
What is the large structure in the pylorus called (right before it becomes the duodenum)?
Torus pyloricus
What happens to the stomach contents when it enters to omasum?
Liquid is extracted and material becomes very dry
What issue can arise with dry material in the omasum?
An omasum impaction. Especially when it is cold, rough feed like straw can become stuck and cause an impaction that spreads into the rumen. not good
What structures does the abomasum poke out between on the left side?
Reticulum and ventral sac of rumen
What is the origin and insertion of the lesser omentum?
Origin: lesser curvature of abomasum
Insertion: Liver
Which side of the cow does the duodenum go up?
The right side, then turns and goes caudally
How is the spleen positioned in the cow abdomen?
It’s on the left dorsal side of the rumen NOT within the greater omentum. The dorsal part of the spleen is also under the retroperitoneal adhesion and attaches to abdominal wall
Which arteries branch off the celiac artery?
Splenic
Left gastric
Hepatic
What does the right rumenal artery branch from?
Splenic a.
What does the left rumenal artery branch from?
Splenic a.
What does the reticular artery branch from?
Left rumenal a.
What does the left gastric artery branch from and then branch into?
From: Celiac a.
To: left gastroepiploic a.
Which grooves does the right rumenal artery run through?
Runs through the right longitudinal groove to the caudal groove
Which groove does the reticular artery run through?
The ruminoreticular groove
Which artery supplies the esophagus?
Reticular artery
What does the gastroduodenal a. branch from and branch into?
From: hepatic
To: right gastroepiploic
What does the right gastric artery branch from?
Hepatic a.
Which groove does the left rumenal artery run through?
Cranial groove and left longitudinal groove
Which two nerve branches supply the ruminant GI tract?
Dorsal vagus
Ventral vagus
Which structures does the dorsal vagus innervate?
Rumen, omasum, and abomasum
Which structures does the ventral vagus innervate?
Reticulum, omasum, and abomasum
What issue can TRP (traumatic reticuloperitonitis) cause?
Vagal indigestion - Extensive inflammation can disrupt the ventral vagus nerve and cause a lack of function
What does the descending duodenum lie within?
The greater omentum and then fuses with mesoduodenum
Which omentum covers the omasum?
Lesser omentum
Which sacs of the rumen lie within the omental bursa?
Ventral sac and ventral blind sac
What is the omental bursa?
The space between the superficial and deep layers of the greater omentum
Which structure takes up most of the abdominal cavity in neonates?
Abomasum - No need for rumen when still on milk
What does the superficial layer of the greater omentum come from and attach to?
Comes from the left longitudinal groove, attaches on the greater curvature of the abomasum, and then inserts on the mesoduodenum
What does the deep layer of the greater omentum come from and attach to?
Comes from the right longitudinal groove and inserts on the mesoduodenum
What lies within the supraomental recess?
Intestines
What is the mesentery called that the jejunum is attached to?
Great mesentery
How many rotations are there in the cow ascending colon?
2
What is the mesentery of the ascending colon fused to?
Left surface of great mesentery
What are the two sections of the ascending colon?
Centripetal
Centrifugal
Which part of the ascending colon runs more inside?
Centripetal
Which part of the ascending colon runs closest to the outside (nearer to the jejunum)?
Centrifugal
What is the flexure of the ascending colon called that comes right after the cecum and before the centripetal colon?
Sigmoidal flexure (S-shaped)
Where is the descending colon located?
On the right face of the dorsal sac of rumen
How can a surgeon get through the greater omentum when doing abdominal surgery?
The edge of the greater omentum can be moved cranially for easy access to intestines within the supraomental recess to avoid cutting through it
