Small animal digestive tract AHS1 Flashcards
What is the line down the ventral midline of the dog?
Linea alba
What are the 4 main muscles of the abdominal wall?
External abdominal oblique Internal abdominal oblique Transverse abdominis Rectus abdominis (down the middle)
What layers of tissue do you cut through when you cut through the linea alba?
Skin
Deep fascia/subcutaneous tissue
Linea alba
Peritoneum
Which way do the muscle fibres run in the external abdominal oblique?
Caudoventrally
What does the EAO form ventrally?
The EAO aponeurosis - thin sheet like tendon
Where does the EAO originate and insert?
From the last ribs/thoracolumbar fascia
EAO aponeurosis on the linea alba
Which way do the fibres run in the internal abdominal oblique?
Cranioventrally (fan caudally)
Where does the IAO originate and insert?
Iliac crest/thoracolumbar fascia and insert on caudal ribs and linea alba
Which way do the muscle fibres run in the transverse abdominis?
Dorsoventral
Where does the transverse abdominis originate and insert?
Transverse processes of lumbar vertebrae and insert on the linea alba in a separate aponeurosis
What runs across the surface of the transverse abdominis?
Spinal abdominal nerves
Where does the linea alba run between?
Xiphoid process to pubic symphysis
What divide up the rectus abdominis?
Tendinous intersections
What is the rectus sheath
Formed from the aponeurotic tendons of the EAO, IAO and TA
What blood vessels serve the craniodorsal abdominal wall?
Phrenicoabdominal artery
What blood vessels serve the cranioventral abdominal wall?
Caudal epigastrics
What blood vessels serve the caudodorsal abdominal wall?
Deep circumflex iliac artery
What blood vessels serve the caudoventral abdominal wall?
Caudal epigastrics
What are the cells that make up the peritoneum?
Flattened mesothelial cells supported by fibrous connective tissue
What are the mesenteries a part of?
Part of the peritoneum
What is the definition of a mesentery?
A double layer of peritoneum suspending an organ
What does retroperitoneal mean?
Behind the parietal peritoneum, outside of the peritoneal cavity
What is the peritoneal cavity?
The area between the visceral and parietal peritoneum
Where does the parietal peritoneum get its blood supply and innervation from?
From what it is in contact with - overlying structures eg. paired vessels and segmental nerves
Where does the visceral peritoneum get its blood supply and innervation from?
From the organ that it is enveloping eg. unpaired vessels and autonomic nerves
What are the three mesenteries?
Mesoduodenum
Mesojejunoileum (great mesentery)
Mesocolon
They are named after the part that they wrap around
How does the blood supply and innervation get to the intestines?
The vessels/nerves run between the peritoneal layers in the mesentery (cut into opposite side of the intestine)
What are the names of the structures that provide the embryonic derivation of the mesenteries/omenta?
Dorsal mesogastrium - around the spleen and the stomach
Ventral mesogastrium - around the liver and the stomach
What do the embryological mesogastria go on to form?
The omenta
Dorsal mesogastrium - greater omentum
Ventral mesogastrium - lesser omentum
What is an omentum?
A peritoneal attachment that is associated with the stomach (looks like lace/spiders web)
How many layers does the greater omentum have?
4
2 double layers as it is the dorsal mesogastrium folded back on itself
How many layers does the lesser omentum have?
2 - the ventral mesogastrium didn’t fold back on itself
What does the greater omentum attach to?
The spleen and the greater curvature of the stomach
What does the lesser omentum attach to?
The liver and the lesser curvature of the stomach
What is the omental bursa?
The space (usually virtual) in between the 2 double layers of greater omentum
Wat are peritoneal folds also called?
Ligaments
eg. falciform, coronary, gastrosplenic
What makes up the foregut?
Distal oesophagus Stomach Cranial duodenum Liver Pancreas (spleen isnt foregut but has the same nerve/blood supply
What makes up the midgut?
Caudal duodenum
All small intestine
Ascending colon
Treansverse colon
What makes up the hindgut?
Descending colon
Rectum
Anus
What artery supplies the foregut?
Coeliac artery
unpaired branch of the aorta
What artery supplies the midgut?
Cranial mesenteric
unpaired branch of the aorta
What artery supplies the hindgut?
Caudal mesenteric
unpaired branch of the aorta
What is the vein equivalent of the coeliac artery?
Gastroduodenal vein
What is the vein equivalent of the cranial mesenteric artery?
Cranial mesenteric vein
What is the vein equivalent of the caudal mesenteric artery?
Iliocolic vein
What do all the abdominal veins from the GI tract drain into?
Hepatic portal vein
How does blood exit the liver?
Through hepatic veins into the caudal vena cava
What abdominal veins drain straight into the caudal vena cava?
Renal
Gonadal
Body wall veins eg. phrenicoabdominal and deep circumflex iliac
Common iliac
What is different about the gonadal veins?
The left gonadal vein drains into the renal vein rather than straight into the caudal vena cava
What is the sensory nerve supply to the abdominal viscera?
General visceral afferent nerves - not very sensitive or specific to location
What is the motor nerve supply to the abdominal viscera?
Autonomic - general visceral efferent nerves
What nerve supplies parasympathetic innervation to the foregut and midgut?
Vagus nerve
What nerves supply parasympathetic innervation to the hindgut and pelvic organs?
Pelvic nerves (S1, 2, 3)
What are the 2 main sources of sympathetic innervation in the abdomen?
Paravertebral/sympathetic chain
Prevertebral chain
(They have different synapses)
What does the paravertebral chain innervate?
The smooth muscle of the paired abdominal viscera
What does the prevertebral chain innervate?
The smooth muscle of the GI tract
What is the 2 main ganglia of the prevertebral chain?
The coeliacomesenteric ganglion
The caudal mesenteric ganglion
What does the coeliacomesenteric ganglion supply?
The foregut and midgut
What does the caudal mesenteric ganglion supply?
The hindgut and the hypogastric nerves to the pelvis
Where does the liver sit?
Between the diaphragm and the stomach
Slightly to the right - more so in larger animals
What is the coronary ligament?
Where the peritoneum covering the liver joins the diaphragm and surrounds the structures here - wraps around caudal vena cava
How many lobes does a canine liver have?
6
What are the lobes divided by?
Fissures
What is the way of remembering where the gall bladder sits?
Queen Goes Riding
Quadrate lobe
Gall bladder
Right medial lobe
What are the 2 different processes of the caudate lobe?
Caudate process and the papillary process (more central)
Where is the impression from the right kidney on the liver?
In the caudate process of the caudate lobe
Where is the impression from the stomach found on the liver?
On the left lateral lobe
What is the notch found on the dorsal surface of the liver?
Oesophageal notch
What is the name of the part of the liver where everything enters?
The porta
What is the portal triad made up of?
Hepatic artery, hepatic portal vein, bile duct
What is the hepatic artery a branch of?
The coeliac artery
Where is the duodenal impression on the liver?
On the right lateral lobe
What is the order of vessels that carry bile out of the liver to the porta?
Canaliculi - ductules - hepatic ducts
What do the hepatic ducts combine to form?
The common trunk
What comes off the common trunk?
The bile duct and the cystic duct
Where does the cystic duct go?
To the gall bladder to store the bile
Where does the bile duct go?
To the duodenum
What is the ductus venosus?
It is a foetal bypass shunt that bypasses the liver as the blood has already been filtered by the mother
Where does the ductus venosus come from and go to?
Comes from the umbilical vein and goes to the caudal vena cava
What is it called when the ductus venosus doesn’t close properly?
Portosystemic shunt
Where in general is the pancreas located?
Nestled in the curve of the duodenum between the ascending and the descending parts
What is the left lobe of the pancreas associated with?
THe greater omentum - it extends around the stomach
What is the right lobe of the pancreas associated with?
The mesoduodenum - the mesentery of the duodenum
What are the names of the openings into the duodenum for contents from the pancreas and the gall bladder?
Major duodenal papilla (more cranial)
Minor duodenal papilla
What empty through the major duodenal papilla?
The bile duct and the major pancreatic duct
What empties through the minor duodenal papilla?
The minor pancreatic duct
What are the two different sphincters in the stomach?
cardiac sphincter - from the oesophagus
Pyloric sphincter - to the duodenum
What are the folds on the inside of the stomach called?
Ruggae
What are the three main branches of the coeliac artery?
left gastric artery
Splenic artery
Hepatic artery
Which arteries are on the lesser curvature of the stomach?
Gastric arteries
Which arteries are on the greater curvature of the stomach?
Gastroepiploic arteries
Which artery is going to the right?
Hepatic artery - liver
which artery is going to the left?
The splenic artery - spleen
What does the left gastric artery come off of?
The coeliac artery
What does the left gastroepiploic artery come off of?
The splenic artery
What does the right gastric artery come off of?
The hepatic artery
What does the right gastroepiploic artery come off of?
The hepatic artery
What supplies the cranial duodenum?
The hepatic branch of the coeliac artery
