digestive anatomy of RUMINANT Flashcards
upper incisors
none, replaced by a hard, fibrous dental pad
what separates the incisors from cheek teeth
diastema
cheek teeth (pre molars and molars) are
incisors are
hypsodont
brachydont
Cheek teeth in herbivores have a complex pattern on the surface due to
invaginations of the enamel layer
As the tooth surface wears down over time, ____ occur on the surface
hard enamel crests; help grind up food
Upper incisors replaced by ____ in ruminants
dental pad
typical foot and mouth disease is seen in
ulceration of the dental pad
dental formula for young and for adults
young:
2(Di 0/4 Dc 0/0 Dp 3/3) = 20
adult:
2(I0/4 C0/0 P3/3 M3/3) = 32
*canine and 4th incisor interchangeable
eruption date for cattle and sheep/ goats
- cattle:
- incisor 1; 1.5-2yrs
- incisor 2; 2-2.5 yrs
- incisors 3; 3-3.5 yrs
- incisors 4; 3.5-4 yrs
- sheep
- incisor 1; 1-1.5 yrs
- incisor 2; 1.5-2 yrs
- incisor 3; 2.5-3 yrs
- incisor 4; 3-4 yrs
initial mastication vs re-mastication or rumination
- initial; quick
- remastication or rumination; slower, plants ground between cheek teeth
lateral chewing movement is due to
- strong masseter and
pterygoid muscles, - relatively narrow, though long mandibles,
- the slope, and roughened surface of the cheek teeth.
tongue is highly
extensible to grasp food
lower incisors cut off grass against
dental pad
Small ruminants have highly mobile ___ which enables them to nibble and crop plants close to the ground
lips
small ruminants have a cleft upper lip known as the
philtrum
negative pressure piston-like action of tongue is aided by
torus; prominence over the caudal part of the body and root
torus has a _______ on its rostral side
transverse lingual fossa
conical papilla
inner surface of lips and cheeks, root of tongue large, pointing backward backward filiform papillae , mechanical in function
lenticular papillae
flat, rounded, mechanical, mainly on torus, act like suction cups
vallate papilla aka circumvallate papillae
very large, on dorsal root of tongue, V shape array, surrounded by deep groove with taste buds on the side
foliate papilla
may be absent, lateral root of tongue, taste buds
true or false the mandible can movie in all 3 planes
true
lateral movement is due to what muscles
strong masseter and pterygoid muscles
when digastric muscle contracts
jaw opens
cattle produce up to ___L saliva a day
150
what is main source of liquid in rumen
saliva
saliva functions
- form food bolus
- provide alkaline buffer to rumen and reticulum
- maintain pH in rumen (contains large quantities of buffer)
- essential for fermentation
large ____ gland covers the more medial ____ gland
parotid
mandibular
the duct of parotid gland runs ventral to the
masseter muscle
the dorsal buccal branch of facial nerve passes over
masseter muscle
the ___ duct passes over the facial artery and nerve
parotid
The
ventral end of the ______ forms a conspicuous swelling in the
intermandibular space which may be mistaken for the mandibular lymph node, although the salivary gland is larger, softer and more rostral.
mandibular salivary gland
what contracts during rumination
what relaxes
rumen and reticulum
cardiac sphincter relaxes
during rumination when the rumen and reticulum contract, the fluid level is raised to the
entrance of the esophagus
how do rumens get the food up during rumination
- rumen and reticulum contract –> fluid raised to entrance of esophagus
- cardiac sphincter relaxes
- cow inspires on closed glottis–> lowers thoracic pressure, esophagus acts like vacuum
- cud passes into it
- cud passes to mouth by reverse peristalsis
- swallows excess fluid
- cud chewed (remasticated) mixed w more saliva
- swallowed again
nasopharynx divided dorsally by the
median pharyngeal septum
the ox has palatine tonsils which ahve follicles that open into _____. These then open into a deep common _____
crypts
sinus tonsillaris
, in most species, the oesophagus decreases in diameter as it approaches the stomach, and the thickness of the muscular wall increases. In ruminants:
the reverse occurs: the overall size of the oesophagus increases, and the wall becomes thinner as the oesophagus approaches the cardia.
muscle type in tunica muscularis
100% skeletal
the mucosa of the esophagus is particularly ____ in the ruminant
cornified
in ruminants fermentation takes place before or after reaching the glandular stomach and the small intestines
before
Fermenting herbivores share a mutually beneficial symbiotic relationship with ______ microorganisms
anaerobic
what do the microorganisms provide that can be used as energy
metabolites- VFAs
assimilation
the process by which living organisms convert food into vitamins, minerals, and other chemicals that the body needs in order to function
In foregut fermenters, this fermentation process takes place ____ the food reaches the glandular stomach, and the small intestines
before
ruminant digestion has led to enlargement of what parts of stomach
cranial non-glandular stomach
gases produced from rumination are removed by
eructation (burping)
rumen stomach
- rumen
- reticulum
- omasum
- abomasum (true stomach)
which stomachs make up the non-glandular stomach where foregut fermentation takes place
rumen, reticulum and omasum
what is the glandular stomach of the ruminants
abomasum
abomasum: rumen/reticulum ration at birth, 2 months and adult
birth 2:1
2 months 1:1
adult 1:9
rumen develops as an outgrowth of the
fundus of stomach, gorws caudal and dorsal (back and over the rest of the stomach which then becomes abomasum)
reticulum develops as an outgrowth of
rumen
omasum develops drom the
lesser curvature of primitive stomach
ruminant stomach development from primitive stomach summary
- rumen outgrowth from fundus
- reticulum outgrowth of rumen
- omasum growth from lesser curvature
- abomasum is rest of stomach
rumen lies on
LHS of abdominal cavity
location of parts of stomach
- reticulum lies cranially against the diaphragm
- omasum lies on RHS cranially
- abomasum lies ventrally
- rumen on LHS
rumen parietal surface is ____
visceral surface is ____
right
left
part of dorsal surface of rumen is attached to
body wall
rumen is divided into __ sacs
6
the 6 sacs of rumen are divided by deep grooves containing
fat, blood vessels, lymphatics, and lymph nodes and nerves
covered by visceral peritoneum
shallow left and right longitudinal grooves are connected cranially and caudally by the
deep cranial and caudal grooves
sacs of rumen: caudal end
The dorsal blind sac and the ventral blind sac are marked off by the dorsal
and the ventral coronary grooves. The blind sacs are separated by the caudal groove which runs left to right. Again, we’ve got a couple of coronary grooves, that go both dorsal and ventral. So they’re named the dorsal coronary groove, and the ventral coronary groove. These demarcate the dorsal and ventral blind sacs
sacs of rumen; cranial end
The dorsal and ventral sacs have bulges at the cranial end; these form the cranial sac, and the ventral recessus ruminis. Again, off
the cranial end of the dorsal and ventral sacs, there’s a cranial sac, and ventrally
there’s a sac called the recessus ruminis. The cranial pillar separates the cranial sac and the recessus ruminis.
cranially, the cranial sac of rumen communicates with the reticulum via the wide
ruminoreticular opening: opening from rumen into reticulum
also where the esophagus enters at the cardia
opposite the cardia is the deep
ruminoreticular groove
ruminal grooves form internal
pillars
separating the rumen and reticulum is the high U shaped
ruminoreticular fold
lining of the rumen internally is what kind of epithelium
keratinized, stratifed squamous epithelium which is thrown up into papillae
the papillae on the inside lining of rumen function
increase SA for transfer of water, small solutes and heat
which areas of internal rumen are the papillae most prominent
where are they absent/ reduced
cranial, ventral and blind sacs
reduced/absent in over the pillars and on part of the dorsal sac
mucosa of the complex stomach is often
folded; increase SA
rumen lamina propria
irregular dense CT, containing capillaries and nerves
lymphoid tissue ABSENT
muscularis mucosa of the rumen
ABSENT
submucosa of the rumen
loose CT
tunica muscularis of the rumen
how many layers, where is it thick
2-3 layers, thick at the pillars
inner circular layer, outer longitudinal layer and also a third layer of internal oblique muscles; only found in rumen and reticulum
where does the tunica muscularis have a third layer of internal oblique muscles, and why
rumen and reticulum,; helps contract and raise fluid level to esophagus for rumination
serosa of rumen has what epithelium
simple squamous or cuboidal or mesothelial cells where is is contunous with the visceral periotneum
part of rumen that attaches to the abdominal roof has
tunica adventitia instead of tunica serosa
the subserosa of the rumen is rich in
adipose tissue
mesothelial cells secrete small amounts of
serous fluid; peritoneal fluid (allows organs to slip past eachother)
the mesothelium layer of the tunica serosa of rumen is continuous with the
peritoneum; borders peritoneal cavity
bloat
ruminal distension from gases of fermentation
primary bloat
aka frothy float; persistent foam mixed with rumen contents
secondary bloat
free gas which separates from ingesta
what are some causes of bloat
- ingestion of large quantities of highly fermentable carbs
- sudden change of ration
- esophageal obstruction (ie foreign body)
- excessive feeding especially during dry season when lots of fermentable carbs
how is primary aka frothy bloat treated
antifoaming agent
how is secondary bloat aka free gas bloat treated
passage of stomach tube or insertion of rumen trocar
reticulum is located between
diaphragm and rumen, lies beneath 6th-8th ribs
reticulum is ____ to opening of esophagus
ventral
hardware disease (traumatic reticuloperitonitis)
where any heavy metals that get eaten drop tor reticulum and can penetrate diaphragm and damage heart
internal reticulum has honeycombed appearance due to
folded epithelium that forms polygonal cells (the spaces in-between called cells)
the ‘cells’ of the honey comb in reticulum are further subdivided by
smaller crests; secondary folds and tertiary folds
the floor of the ‘cells’ of the reticulum honeycomb are covered with
small papillae
near the cardia, the rumen and reticulum merge at the _____
atrium ventriculi
the cardia opens into the _____ which connects esophegal opening with reticulo-omasal orifice
reticular groove
what connects the esophageal opening with reticulo-omasal orifice
reticular groove
when the reticular groove is closed, this conducts food from esophagus to
omasum (by-passing the rumen)
reticulum epithelium
stratified squamous, keratinized
lamina propria of reticulum
dense irregular CT, elastic fibers
how does reticulum layers differ from rumen
under lamina propria the reticulum has muscularis mucosae at the to the top of the ‘cells’, the primary and secondary folds
the primary and secondary folds of the muscularis mucosa of the reticulum have
apical bundles of longitudinal smooth muscle; form rings around the tops of the ‘cells’
rumen has NO
muscularis mucosa
what layers does reticulum have under the muscularis mucosa
submucosa,
tunica muscularis
serosa
(same as rumen)
omasum is rounded organ to the ____ of reticulum
right
how is omasum attached to the retiuclum
short neck called collum omasi
does the omasum contact the right abdominal wall
yes is cattle but not in small ruminants
fluid passes from the reticulum through the
reticulo-omasal opening
the reticulo-omasal opening contains relatively large ____
cornified papillae
the omasal groove lies opposite
the free edge of the laminae
the omasal groove is crossed by the the muscular
omasal pillar near the opening to abomasum
omasum is commonly called
book
large internal folds: omasal laminae, covered in cornified papillae, v large SA
what are the pages of the book in omasum called
omasal laminae
the spaces inbetween the pages of the book (aka the omasal laminae) in the omasum are called
what are they packed with
interlaminar recesses
packed w finely ground ingesta
omasum epithelieum
stratified squamous, keratinized, lateral papilla
(same as rumen and reticulum)
lamina propria of omasum
dense, irregular CT w extensive capillaries
omasum muscularis mucosa
uninterrupted double layer, extends all way into folds
muscularis mucosae in omasum seperates the
lamina propria from submucosa
inner ciruclar layer of tunica muscularis in the omasum extends
up laminae between the 2 layers of muscularis muscosa
so within laminae of the omasum there are how many layers of smooth muscle
3; double layer of muscularis mucosa and inner circular of tunica muscularis layer between these 2
omasum submucosa
loose CT
omasum tunica muscularis
inner circular layer penetrates into folds (recall inbetween the double layer of the muscularis mucosa)
muscle layers in folds differ to rumen and reticulum
serosa of omasum
same as rumen
abomasum is the
true stomach
what is abomasum lined w
glandular mucosa
fundus of abomasum is near
body is
pylorus is
xiphoid between rumen and reticulum
body is ventral near midline between omasum and ventral sac of rumen, then turns right
pylorus is dorsolateral behind omasum
opening to abomasum is called ______ and is flaked by 2 folds of mucosa called the _______
omaso-abomasal opening
vela abomasica
omasum to abomasum marks the epithelium change from
non glandular to glandular
stratified squamous keratinized to simple columnar
omasum to abomasum lamina propria change
dense irregular CT –> loose irregular CT
There are two main changes from omasum to abomasum:
The epithelium changes from stratified squamous, keratinized to simple columnar.
This transition occurs at the apex of the folds in large ruminants, and halfway down
the omasal side in small ruminants.
The lamina propria changes from dense, irregular connective tissue in the omasum, to loose connective tissue under the
columnar epithelium of the abomasum
2 main glandular regions in the abomasum
1) proper/ fundic glands in most of fundus region and body
reddish grey
2) pyloric glands in pyloric region
yellowish
is the pyloric sphincter in the internal abomasum well developed
no, but there is a prominent rounded torus pyloricus on side of lesser curvature
torus pyloricus
round prominence on side of lesser curvature of abomasum
what kind of glands exist surrounding the omasoabomasal orifice
small cardiac gland region
gastric groove runs from
the opening of the oesophagus through the reticulum,
the omasum and into the abomasum.
as you move caudally the gastric groove spirals
clockwise, so that the opening faces at first caudally, then to the left and then cranially
what does gastric groove do
It directs liquids from the oesophagus to the abomasum. This is most important in young ruminants, as it enables milk to bypass the fermentative activity
of the rumen
what happens to gastric groove when a young animal suckles
the lips of the reticular part of the groove close over forcing a channel from the oesophagus to the omasum, bypassing the rumen and reticulum and the milk
then flows into the abomasum
reflex control
describe reflex control of gastric groove closing when young animals suckle
afferent pathway
stimulated by suckling in young animals
efferent pathway – which tells the reticular part of the groove to close over – travelling in the vagus nerves
tunica muscularis of gastric groove
The lips of the groove are the internal oblique muscle, and the floor of the groove is the outer longitudinal muscle. There’s also some striated muscle fibres
in there as well.
dorsal sac of rumen is attached to
crura of diaphragm
the left psoas muscles back to
L3/4 in retroperitoneal space
does the rumen lie entirely in peritoneal cavity
no because it is supported by the left psoas muscles back to L3/4 in the retroperitoneal space
external support for greater and lesser omentum
The greater and lesser omentum are obviously attached to the forestomaches, but they do not play a part in the actual
support of the organs in adults.
lesser omentum joins the visceral surface of liver to
the omasum, lesser curvature of abomasum and cranial border of the duodenum
hepatogastric ligament connects
stomach to liver
hepatoduodenal lig connects
duodenum to liver
what 2 ligaments make up the lesser omentum
hepatoduodenal ligament
hepatogastric ligament
greater omentum in ruminants has 2 layers
what are they
- superficial from left longitudinal groove
- deep layer form right longitudinal groove
each of the 2 layers of the greater omentum consists of
two layers of peritoneum, separating the omental bursa.
what forms a sling for intetsines
supraomental recess
ventral sac of rumen sits in
omental bursa
the ventral descending duodenum supports which layer of the greater omentum
both superficial and deep
most muscle in rumen is what kind of muscle
smooth
withe exception of some striated muscle fibers from esophagus, which penetrate into rumen and reticulum
the longitudinal muscles divide into 2 main streams at the cardia:
One follows the reticular groove to the omasum, and then spreads over the omasum and
abomasum.
The other spreads over the dorsal sac of the rumen, and these are
referred to as the external oblique fibres
where are circular muscle fibers found
Throughout EXCEPT dorsal sac of rumen
Prominent in gastric groove and sphincters
where are the the internal oblique muscles found
A third layer of internal oblique muscles is found only in the rumen and reticulum.
3 main branches of ceoliac artery
splenic, hepatic, left gastric
4 main arteries of ruminant stomach
right ruminal artery
left ruminal artery
reticular artery
left gastric artery
right ruminal artery
- Main supply to rumen/reticulum
- Arises from splenic (usually)
- Runs in right longitudinal groove
- Branches as coronary arteries
which artery is main supply to rumen/reticulum
right ruminal artery
left ruminal artery
- From coeliac, splenic or left gastric
- Runs through cranial and left longitudinal groove
- Dorsal and ventral branches
reticular artery
- From left ruminal artery
- Through left lip of reticular groove
- Supplies reticulum
left gastric artery
- From coeliac artery
- Over omasum to lesser curvature of abomasum
- Joins the right gastric (ex hepatic)
- Branches to left gastroepiploic
- May also be off right ruminal
- Join the right gastro-epiploic from hepatic artery
summary of blood supply
- Left and right gastroepiploic arteries → greater curvature
- Left and right gastric arteries → lesser curvature
- Left and right ruminal arteries → rumen (longitudinal grooves)
- Reticular artery → reticulum
main vein is
splenic vein
splenic veins drains all gastric arteries except
right gastric and right gastroepiploic arteries.
These are drained by branches of the gastroduodenal vein
Splenic and gastroduodenal veins both join the
hepatic portal vein to liver
parasympathetic innervation
- Dorsal and ventral vagal trunks
- Major control
sympathetic innervation
- Follow blood vessels from coeliac and cranial mesenteric plexuses
- Minor role
rumen displaces all intetsines to the
right
brunner’s glands are found
entire lenght of duodenum
descending duodenum is found on
right dorsal body wall
intestines sit within the sling of the
supraomental recess
jejunum has numerous tight coils surrounding the spiral loop of
ascending colon
paneth cells in what species
In ruminants, horses, man, rats & mice
NOT in pigs, carnivores
where are paneth cells seen
in the base of the crypts of Lieberkühn in the small
intestine:
small intestine in ruminants contain what 4 cells
absorptive cells (enterocytes),
goblet cells,
enteroendocrine cells,
paneth cells
paneth cells produce
secretory granules which contain antimicrobial peptides and immunomodulating proteins
functions of paneth cells
- The dense granules produced by Paneth cells contain
antimicrobial peptides and immunomodulating proteins. - These function to regulate
the composition of the intestinal flora. - These antimicrobial molecules are key mediators of interactions between the host, and the microbiota of the rumen.
- This includes helping to maintain a homeostatic balance with colonizing microbiota, as
well as providing innate immune protection from enteric pathogens. - Paneth cells secrete factors that help sustain and modulate the epithelial stem and progenitor
cells that cohabitate in the crypts. - This helps rejuvenate the small intestinal epithelium
describe caecum of ruminants
Wide, slightly s-shaped
High on right of abdomen
Apex directed caudal & left
Near pelvic inlet
the ascending colon: 3 loops
Proximal S-shaped loop
- In line with caecum
Spiral loop
- Flat disc-shaped
- Centripetal loops
→ Central flexure
→ Centrifugal loops
Distal Loop
- Caudal, then cranial
transverse colon
short, dorsal to pancreas
descending colon
- Runs along ascending duodenum
- Close to dorsal abdominal wall
- Mesocolon lengthens near pelvis
- Greater mobility for rectal exams
is the anus glandless
yes
liver is almost entirely on ___ side
right
where is liver most cranial and most caudal
- Most cranial at 6th intercostal
- Most caudal at right kidney at 13th rib
gall bladder extends beyond
ventral margin
liver lobes in cattle/sheep
left lobe is single
right lobe is single (not divided into medial and lateral)
quadrate lobe
caudate lobe
small papillary process
round ligament of liver is remnant of
umbilical vein
pancreas where is right and left lobes found
Right lobe
Associated with descending
duodenum
Left lobe
Retroperitoneal
Between the rumen, the liver and
diaphragm
Which of the following dental formulas for the ruminant is INCORRECT?
A.
2(I0/4 C0/0 P3/3 M3/3) = 32
B.
2(Di 0/4 Dc 0/0 Dp 3/3) = 20
C.
2(I0/3 C0/1 P3/3 M3/3) = 32
D.
2(I4/4 C0/0 P3/3 M3/3) = 32
D.
2(I4/4 C0/0 P3/3 M3/3) = 32
goat with 2 permanent incisors is approx how old
6mo
14mo
2 yo
2.5 yo
14 mo
The tongue in the ruminant can be used as a piston, generating a negative pressure in the mouth for suction. Which of the following structures does NOT contribute to generating this negative pressure?
A.
Lingual torus
B.
Lenticular papilla
C.
Conical papilla
C.
Conical papilla
Movement in the frontal and transverse planes of the mandible in ruminants is freer than it is in carnivores. This lateral movement is due to ruminants having strong:
Masseter and pterygoid muscles
Which compartment of the ruminant stomach is indicated by an asterisk (*) in the image? (look at pic)
Abomasum
What type of mucosa lines the abomasum; glandular or non glandular
Glandular
The rumen occupies the majority of which side of the abdomen in the cow?
Left
What groove is shown at A? see pic q 8 practice quiz
***go through practice quiz, multiple pic questions!!!
Left longitudinal groove
Which compartment of the complex stomach has 3 layers of smooth muscle within laminae? (book)
Omasum
When a young animal suckles, the gastric groove closes over. This creates a channel which funnels milk from the oesophagus to the __________, bypassing the __________ and __________. The milk then flows into the __________.
Omasum; rumen; reticulum; abomasum
Which of the following is NOT present in the abomasum?
A.
Torus pyloricus
B.
Vela abomasica
C.
Papillae
D.
Cardiac glands
Papillae
Which groove of the rumen does the superficial layer of the greater omentum arise from?
Left longitudinal groove
Which groove of the rumen does the deep layer of the greater omentum arise from?
Right longitudinal groove
Which sac of the rumen sits in the omental bursa?
Ventral sac
What structure do BOTH the deep and superficial layers of the greater omentum attach to, creating the supraomental recess which acts as a sling for the intestines?
Ventral descending duodenum
Which of the following cell types is found in the small intestine of the ruminant, but NOT in the carnivore?
Paneth cells
In the cow, is the spiral loop of the ascending colon sacculated?
No
Which of the following CORRECTLY describes the arrangement of the liver lobes in the ruminant?
Single left lobe; single right lobe; quadrate lobe; caudate lobe with small papillary process
