Ruminant Stomach and Intestine Flashcards
What is a ruminant?
mammals that are able to acquire nutrients from plant-based food by fermenting it in a specialized stomach prior to digestion, principally through bacterial actions (stomach fermenter)
- also regurgitate food so it can be chewed again
Where does fermentation occur in the horse?
cecum and ascending colon
What are the four regions of the ruminant stomach?
- Reticulum (stomach with net)
- Rumen (papillary stomach)
- Omasum (stomach with leaves)
- Abomasum (true stomach)
What does the orientation and size of the abdominal viscera vary with?
age and pregnancy
How are the viscera arranged in a newborn calf?
- liver and abomasum are enlarged compared to a 5 year old cow
- enlarged abomasum displaces the liver to the right of the abdomen
How are the viscera arranged in a 5 year old cow?
- the rumen is large and occupies the entire left side of the abdomen
- The liver is pushed cranially by the omasum
How are the viscera arranged in a heavily pregnant cow?
- uterus displaces the rumen dorsally and abomasum cranially
How does the ruminant stomach sit in the cow?
- laterally compressed with the bulk of it displaced to the left (fills right side of abdomen)
- Extends from the diaphragm to the pelvic inlet
- Sometimes caudoventral part extends well over median plane into the right half of the abdominal cavity
What does the parietal surface of the ruminant stomach lay against? Visceral surface?
Parietal surface: is in contact with the left abdominal wall, diaphragm, and floor of the abdomen
Visceral surface: faces the right and is related chiefly to the intestines and the liver
Where are the dorsal and ventral curvatures/ where do they lay?
Dorsal curvature: lies against the diaphragm and dorsal aspect of the abdominal cavity
Ventral curvature: follows the contour of the abdominal floor
What divides the rumen into various compartments?
external grooves on the surface correlate with internal pillars that divide the rumen into various compartments
What are the grooves on the surface of the rumen?
- cranial and caudal grooves
- L/R longitudinal grooves
- Dorsal and ventral coronary grooves
- L/R accessory grooves
What separates the ventral ruminal sac from the caudoventral blind sac?
the ventral coronary groove/pillar
What separates the dorsal ruminal sac from the caudodorsal blind sac?
the dorsal coronary groove/pillar
What is the insula ruminis and where is it found?
A sac located between the right accessory groove and the right longitudinal groove
How does a vet obtain access to the rumen in the ox?
through the paralumbar fossa (left)
Where does the spleen attach in the ox and where is it located?
attached to the craniodorsal aspect of the atrium of the rumen; located in the left hypochondriac region
What is the intraruminal orifice (or intraruminal osteum)
an internal ring that is bound by the right and left longitudinal pillars and the cranial and caudal pillars and is the boundary between the dorsal and ventral ruminal sacs
What is the ruminoreticular fold?
separates the reticulum from the atrium in ruminents
What is found in the dorsal-most layer and ventral-most layer of the rumen?
dorsal = gas bubble ventral = liquid zone
Where is the reticulum located?
at the cranioventral part of the stomach and lies immediately caudal to the left half of the diaphragm
Where does traumatic reticulitis or hardware disease occur? What causes it?
In the reticulum. Occurs when metal objects become lodged within the reticulum
What happens to the reticular groove in the unweaned animal and why?
it closes to form a tube-like gastric groove, which conveys milk directly from the esophagus to the abomasum
What can happen during traumatic reticulitis or hardware disease?
- sharp objects can pierce through the cranial aspect of the reticulum and the diaphragm and may puncture the pericardium and/or heart
How is traumatic reticulitis or hardware disease treated?
placement of magnets into the reticulum collects metal scraps and prevents them from puncturing through the walls of the reticulum
What causes/stimulates the formation of the gastric groove?
- stimulated by ADH
- In adult, use of drugs (eg: copper sulfate) can help crate the tube so that certain products bypass the fore-stomachs and travel directly into the abomasum
What is the sequence of flow with an open reticular groove?
cardia -> reticular groove -> reticulum -> ruminoreticular orifice -> rumen -> ruminoreticular orifice -> reticulum -> regurgitation
What is the sequence of flow with a closed reticular groove?
cardia -> reticular groove -> reticulo-omasal orifice -> omasal groove -> omasoabomasal orifice -> abomasal groove
What is the cavity of the omasum occupied by?
numerous longitudinal folds, or laminae
What are the two openings of the omasum?
- reticulo-omasal orifice
- omasoabomasal orifice
What is the inner appearance of the omasum?
has many parallel folds of varying sizes (omasal laminae) with interlaminar recesses between them
- laminae are studded with papillae
What is the inner appearance of the abomasum?
Has spiral folds that are permanent (do not dissapear with distention as is the case with rugae)
What does the torus pyloricus do and where is it?
A round protuberance on the internal aspect of the pylorus on the side of the lesser curvature that enhances the pyloric sphincter
Where are the majority of stomach compartments located?
deep to the ribs
Where is the border of the base of the paralumbar fossa? What is the cranioventral and caudoventral border?
Base: along the tips of the lumbar transverse processes
Cranioventral: last rib
Caudoventral: ridge formed by the part of the internal abdominal oblique muscle that extends from the tuber coxae to the ventral end of the last rib of the ox
What are the attachments of the greater omentum?
- abomasum (greater curvature)
- reticulum
- Left longitudinal groove (superficial leaf)
- Right longitudinal groove (deep leaf)
- Also mesoduodenum (of descending duodenum, from cranial to caudal duodenal flexure), left lobe of pancreas, spleen
What are the attachments of the lesser omentum?
- abomasum (lesser curvature)
- Omasum (base)
What is formed by the superficial and deep leaves of the greater omentum?
Form a sling within which the bulk of the intestines reside
- Also forms a bursa within which the ventral ruminal sac resides
What is the main blood supply of the rumen and where is it found?
- right ruminal artery ( a branch of the splenic a.) which courses in the right accessory groove, through the caudal groove. (gives off R/L dorsal and ventral coronary aa. within corresponding coronary grooves)
- Left ruminal a. which passes through the cranial groove from right to left and extends into the left accessory groove.
What is the main blood supply to the omasum?
left gastric artery (branch of the celiac artery)
What supplies the reticulum with blood?
- reticular artery of the left ruminal artery
- Accessory reticular artery (may branch from left gastric a.) (gives rise to left gastroepiploric a.)
What supplies the greater and lesser curvatures of the abomasum with blood?
greater curvature: left and right gastroepiploric aa.
lesser curvature: left and right gastric aa.
What is the major innervation of the rumen, omasum and reticulum?
dorsal vagal trunk
- the atrium of the rumen, omasum, reticulum, and abomasum are innervated by branches from both the dorsal an ventral vagal trunks
What is the supraomental recess bound by?
bound by the rumen on the left and the greater omentum on the right
True or false? During pregnancy, the Gravid uterus may extend into the supraomental recess.
True
True or false? The major duodenal papilla of large ruminants drains both the pancreatic duct and bile duct.
False. only the bile duct in large ruminents. The pancreatic duct travels to the minor duodenal papilla instead
True or false? The major duodenal papilla of small ruminants drains both the pancreatic duct and bile duct.
True
What are the parts of the spiral loop?
- centripetal gyri
- Central flexure
- Centrifugal gyri
Which gyri is always on the outer-most surface of the spiral?
Centrifugal gyri
Which gyri carries ingesta into the loop?
centripetal gyri
What supplies the jejunum with blood?
- jejunal aa. of the cranial mesenteric artery
- Collateral branch (only in ruminants)
What supplies the ileum with blood?
- ileal aa. of jejunal a. and collateral branch
- Mesenteric ileal branch of ileocolic a.
- Antimesenteric ileal branch of cecal a. of ileocolic a.
What part of the ascending colon is supplied by the colic branch of ileocolic a.? Right colic a.?
Colic branch: supplies first half of ascending colon: proximal loop, centripetal portion of spiral loop
Right colic a: supplies second half of ascending colon: centrifugal portion of spiral loop, distal loop
What does the collateral branch of the cranial mesenteric a. supply?
contributes to blood supply of the last centrifugal loop of the ascending colon and distal jejunum
