Lecture 3: The Ruminant Stomach Flashcards
what are the 4 compartments of the ruminant stomach?
- reticulum
- rumen
- omasum
- abomasum
name some ruminant species other than cattle.
deer, sheep, goats, elk, antelope, moose, giraffe, camels, llamas
what is unique about the compound stomach? why was it developed?
it provides an upper digestive tract capable of promoting growth of fermentative microorganisms which produce unique enzymes that can break down the low quality foodstuffs ingested (ie cellulose)
what structures can be seen from the left side in normal anatomic orientation?
- reticulum
- part of abomasum
- rumen (specifically cranial sac, insula and ventral sac)
what structures can be seen from the right side in normal anatomic orientation?
reticulum
omasum
abomasum
pylorus
what structures can be seen from the dorsal view in normal anatomic orientation?
rumen spleen liver omasum abomasum
which side does the rumen occupy almost all of?
the left abdominal cavity
which surface of the rumen lies adjacent to the diaphragm and left abdominal wall?
the parietal surface
which side of the rumen faces the intestines, liver, omasum and abomasum?
the visceral surface
- which side of the body is most of the reticulum located?
2. describe its anatomical location
- primarily on the left
2. it lies in the most cranial compartment, dorsal to the xiphoid process of the sternum
which side of the body is omasum located? and descibe the location of the omasum
it is located cranially on the the RIGHT side of the abdominal cavity, caudal to the reticulum
describe the location of the abomasum
it is located on the right ventral floor of the abdominal cavity dorsal and caudal to the xiphoid process
how is the rumen attached in the body?
it is only attached to the abdominal wall dorsally. this allows great freedom of movement.
how does the cranial sac of the rumen communicate with the reticulum?
the ruminoreticular orifice
what surrounds the ruminoreticular orifice? (2 things)
the ruminoreticular fold and the esophagus
how does the esophagus incompletely surround the ruminoreticular orifice?
via the cardia
what is located on the mucosal surface of the rumen?
ruminal papillae
what 3 things does the reticulum communicate with and how?
- the esophagus at the cardia
- the cranial sac of the rumen via the ruminorecticular orifice
- the omasum via the reticulo-omasal orifice
what is located along the cranial wall of the reticulum extending from the cardia to the reticulo-omasal orifice?
the reticular groove
what is the function of the reticular groove?
the reticular groove consists of two muscular folds. when they contract, ingesta can bypass the rumen and to directly to the omasum
what is the omasal groove?
it is a continuation of the reicular groove in the omasum. the omasal groove bypasses the omasum.
what is significant about the reticular groove and the omasal groove? when would they be used?
the function of these grooves is most important in the suckling calf when the ingested high protein milk can only be digested in the abomasum, the true glandular stomach.
describe the location of the reticulum. what is significant about the location of the reticulum?
the reticulum lies up against the peritoneal side of the diaphragm.
because of this location, heavy foreign objects that are accidentally swallowed and retained can often penetrate the cranial wall of the reticulum and cause inflammation of peritoneal and pleural linings as well as involvement of the heart and liver
what is the common term for the traumatic reticulitis?
“hardware disease”
what are reticular crests?
honeycomb-like cells formed by mucosal folds on the mucosal surface of the reticulum
describe the location of the omasum
located on the RIGHT side above and cranial to the xiphoid cartilage contained within the thoracic part of the abdominal cavity
describe the omasal mucosa. there are specifically 2 structures we need to know.
the omasal mucosa forms broad flat leaves called (1) omasal laminae (omasal leaves) that are covered with sort and stubby (2) papillae.
what is the function of the papillae?
to increase the absorptive surface area for water and volatile fatty acids (which is why the material found in the omasum is always very dry).
what is the abomasum referred to?
the “true” glandular stomach
where is the abomasum located?
dorsal and caudal to the xiphoid cartilage
name the 3 parts of the abomasum
the fundus, body and pyloric region
what does the omasal groove continue as once it reaches the abomasum?
it continues as the abomasal groove through the omasoabomasal orifice.
describe the mucosa of the abomasum. there are 2 structures we need to know.
the mucosa has many spiral folds called (1) rugae in the body a (2) torus pyloricus present at the pylorus
what is the function of the torus pyloricus?
it functions to help close the pylorus
the compound stomach is supplied by branches of which artery?
the celiac artery
the splenic artery gives rise to 2 arteries. what are they and what do they supply?
- the right ruminal artery - supplies caudal half of rumen including the blind sacs
- the left ruminal artery - supplies the cranial half of the rumen
what artery branches off the left ruminal artery and what does it supply?
the reticular artery - it supplies the reticulum
what does the left gastric artery supply?
- greater curvatures of the omasum
2. lesser curvatures of the abomasum
what branches off the left gastric artery? what does it supply?
the left gastroepiploic artery - it supplies the other curvatures of the omasum and abomasum
what does the hepatic artery supply?
the distal half of the abomasum
what 2 arteries branch off the hepatic artery and what do they supply?
- the right gastric artery - lesser curvature of the abomasum
- the right gastroepiploic artery - greater curvature of the abomasum
what does the dorsal vagal trunk innervate?
the rumen
visceral surfaces of the reticulum and omasum
lesser curvature of the abomasum
what does the ventral vagal trunk innervate?
the parietal surface of the stomach including the reticulum, omasum and right abomasum
vagal innervation is responsible for what SIX functions?
- ruminoreticular contraction cycles
- omasal contraction cycle
- eructation
- regurgitation
- reflex closure of reticular (gastric) groove
- abomasal motility and secretion
what does the greater omentum form?
a two-layer sling between the descending duodenum on the right side and the caudal part of the rumen on the left side.
what is the superifical leaf of the greater omentum attached to?
the left longitudinal groove laterally and the greater curvature of the abomasum cranially
what does the superifical leaf of the greater omentum lie against?
the parietal peritoneum of the ventral abdominal wall
what does the deep leaf of the greater omentum attach to?
the right longitudinal groove of the rumen
what does the ventral sac of the rumen lie within?
the omental bursa
what two structures rest on the dorsal surface of the deep leaf (in the sling)?
what is this space called?
- the small intestine
- spiral colon
the supraommental recess
define supraomental recess
space that is open caudally and occupied by the intestines
what is clinically significant about the free border made by the superficial and deep leaves?
during surgery through the right paralumbar fossa, you have to pull the greater omentum cranially to reach the small intestine, colon and cecum
what is the greater omentum also attached to?
the greater curvature of the abomasum
what does the lesser omentum attach to?
the liver, the right side of the omasum and the lesser curvature of the abomasum
