Unit 6 - Liver, Omentum, Stomach

What are the lobes of the equine liver?

- Right

- Quadrate

- Left medial

- Left lateral

- Caudate lobe with caudate process (no papillary process)

Do horses have a gall bladder? What does this mean for bile flow in the horse?

- No

- Bile flows from hepatic ducts to common hepatic duct to major duodenal papilla

What is embedded in the diaphragmatic (parietal) surface of the equine liver?

- Caudal vena cava

What structures can be found on the visceral surface of the equine liver?

- Hilus/port

- Gastric impression

- Duodenal impression

- Colic impression

- Cecal impression

What structures can be found on the dorsal border of the equine liver?

- Renal impression

- Esophageal impression

What can be found at the hilus/porta of the equine lung?

- Portal vein

- Hepatic artery

- Hepatic nerves

- Common hepatic duct

- Lymphatic vessels

What is the colic impression of the equine liver in contact with?

- In contact with the diaphragmatic flexure and right dorsal colon

What is the cecal impression of the equine liver in contact with?

- In contact with the cranial part of the base of the cecum

What is the renal impression of the equine liver in contact with?

- Right kidney

What are the ligaments of the equine liver?

- Triangular ligaments

- Coronary ligament

- Falciform ligament

- Hepatorenal ligament

Where do the equine triangular ligaments course?

- Right - Between right liver lobe and costal part of the diaphragm

- Left - Between left liver lobe and central tendon of the diaphragm

What two things does the equine coronary ligament connect? Where does it course?

- Connects the liver to the diaphragm

- Courses between the triangular ligaments

What are the attachments of the falciform ligament? What does it contain?

- Attaches the quadrate and left medial liver lobes to the sternal part of the diaphragm and floor of the abdomen

- Contains the round ligament of the liver

What are the attachments of the hepatorenal ligament?

- Attaches the caudate process to the right kidney and base of cecum

What are the boundaries for liver biopsy in the horse?

- Right side: Line between tuber coxae and olecranon, line between tuber coxae and point of the shoulder, between ribs 11 and 14.

How does the bovine liver differ from the equine liver positionally?

- Liver is displaced to the right of the median plane; right lobe is caudodorsal, left lobe is cranioventral

What are the lobes of the bovine liver?

- Right

- Left

- Quadrate

- Caudate (papillary process and caudate process)

Where is the gall bladder located in the bovine liver?

- Located between the right and quadrate lobes

What is attached to the diaphragmatic surface of the bovine liver? Describe its course.

- Falciform ligament is attached to the diaphragmatic surface from the esophageal impression to the notch for the round ligament of the liver

Which part of the falciform ligament/liver is devoid of serous covering?

- Area attached to the diaphragm

What structures are found on the visceral surface of the bovine liver?

- Hilus/porta

- Omasal impression

- Reticular impression

- Abomasal impression

What is found on the right border of the bovine liver?

- Impression for right kidney

What is found on the ventral border of the bovine liver?

- Gall bladder fossa (more distinct in sheep and goat)

- Notch for round ligament

What is found on the dorsal border of the bovine liver?

- Groove for caudal vena cava

- Esophageal impression

Where do the triangular ligaments of the bovine liver course?

- Right: Between right liver lobe and the dorsal abdominal wall

- Left: Between the esophageal impression and diaphragm ventral to the esophageal hiatus

Where does the coronary ligament course in the bovine liver?

- Connects the liver to the diaphragm; Courses between the triangular ligaments

Where does the hepatorenal ligament course in the bovine liver?

- Attaches caudate process to the ventral surface of the right kidney

What are the boundaries for a bovine liver biopsy?

- Right side: Intersection of the 11th intercostal space and a line drawn from the olecranon to the tuber coxae

What are the lobes of the porcine liver?

- Left lateral

- Left medial

- Quadrate

- Right medial

- Right lateral

- Caudate lobe with caudate process

Does the porcine liver have contact with the right kidney?

- No

The porcine kidney is ______________.

- Fibrous

The equine stomach is relatively __________. What is its capacity?

- Small

- 5-15 L capacity

Where is the equine stomach situated?

- Situated from 9th to 15th ribs

What is the parietal surface of the equine stomach in contact with?

- With the diaphragm and liver

What is the visceral surface of the equine stomach in contact with?

- In contact with the terminal part of the ascending colon, transverse colon, pancreas, descending colon, small intestine, and greater omentum

Where does the gastrosplenic ligament course in the horse? What is it continuous with?

- Courses from the left region of the greater curvature of the stomach to the hilus of the spleen

- Continuous ventrally with the greater omentum

Where does the gastrophrenic ligament course?

- Connects greater curvature of the stomach from the cardia to the left side with the crura of the diaphragm

List some reasons why it is difficult for the horse to vomit.

- Tunica muscularis in the distal 1/5 of the esophagus is twice as thick as in other regions of the esophagus forming a strong lower esophageal sphincter.

- Tunica muscularis in distal 1/5 of esophagus is entirely smooth muscle and is, therefore, not under voluntary control.

- Esophagus enters the stomach at an oblique angle. When pressure within the stomach increases, the cardia closes tighter.

- Stomach does not touch the ventral abdominal wall. It is situated dorsal to the ventral and dorsal portions of the ascending colon. Abdominal muscular contractions associated with vomiting will first be absorbed by the ascending colon.

- Saccus cecus and pyloric antrum are positioned cranial to the cardia. Gastric contractions are more likely to force contents into these two regions rather than through the cardia.

What does the greater omentum connect in the horse?

- Connects the greater curvature of the stomach and the initial part of the duodenum with the terminal part of the large colon and initial part of the small colon (which connect to the dorsal body wall)

Where is the omental bursa located?

- Located between the superficial and deep layers of the greater omentum

What does the lesser omentum connect in the horse?

- Connects the lesser curvature of the stomach and the first part of the duodenum with the liver

What is found within the equine lesser omentum?

- Hepatogastric ligament

- Hepatoduodenal ligament

What is the epiploic foramen?

- Connection between the peritoneal cavity and omental bursa

On which side of the horse is the epiploic foramen found? What is the dorsal and ventral boundary?

- Right side

- Dorsal boundary: Caudate process of the liver (CPL) and caudal vena cava

- Ventral boundary: Pancreas, hepatoduodenal ligament (HDL) and hepatic portal vein

What percentage of the stomach in the ox is made up by the rumen, reticulum, omasum, and abomasum? What is its capacity?

- Rumen: 80%

- Reticulum: 5%

- Omasum: 8%

- Abomasum: 7%

- Capacity: 60 L

What percentage of the stomach in the small ruminant is made up by the rumen, reticulum, omasum, and abomasum? What is its capacity?

- Rumen: 75%

- Reticulum: 8%

- Omasum: 4%

- Abomasum: 13%

- Capacity: 15-18 L

What is the intraruminal orifice?

- Opening between the dorsal and ventral sacs of the rumen

What is the ruminoreticular orifice?

- Opening between the rumen and reticulum

In the sheep and goat, the ventral sac is relatively _________ and extends more to the ________ of the median plane than in the ox. The caudoventral sac is more _______________ than the caudodorsal blind sac.

- Larger

- Right

- Extensive

In the small ruminant, does the left longitudinal groove connect with the caudal groove?

- No

Describe the dorsal coronary groove of the small ruminant rumen.

- Dorsal coronary grooves are very short or absent

Where is the reticulum located?

- Located between 6th, 7th, or 8th ribs

The reticulum lies to the _________ of midline.

What is the parietal surface of the reticulum in contact with? The visceral surface?

- Parietal surface: Diaphragm and liver

- Visceral surface: Rumen

Is the reticulum larger in the sheep/goat or the ox?

- Relatively larger in the sheep and goat

How is the gastric groove divided?

- Reticular groove: Located between the cardia and the reticulo-omasal orifice

- Omasal groove: Located between the reticulo-omasal and omasoabomasal orifices

- Abomasal groove

How many ruminal/reticular contractions are there per minute? What does it mean when there are less or more?

- 1-3 per minute

- Less: ruminal atrophy

- More: hypermotility

Explain how ruminal/reticular contractions are stimulated.

- Roughage and fluid tickle the reticulum causing 2 reticular contractions then 2 ruminal contractions

What stimulates the growth of ruminal papillae?

- VFAs

Ruminal contractions can be seen where?

- In the left flank

Where can reticular contractions be felt?

- Left 6th-7th intercostal space

Where is the omasum located?

- Mainly to the right of midline, opposite te 7th-11th ribs

What is the parietal surface of the omasum in contact with? The visceral surface?

- Parietal surface: In contact with the diaphragm, liver, and body wall (7th-9th ICS)

- Visceral surface in contact with the rumen, reticulum, and abomasum

Describe how the omasum differs in the sheep and goat.

- Much smaller than the reticulum, located at 9th-10th ribs and has no contact with the body wall

The omasum is thought to act as what?

- As a pump transferring material from the reticulum to the abomasum as well as aiding in absorption

What is the parietal surface of the abomasum in contact with? The visceral surface?

- Parietal surface is in contact with the abdominal floor

- Visceral surface is in contact with the rumen and omasum

Where is the fundus of the abomasum located?

- Xiphoid region

Where does the body of the abomasum extend? The pylorus?

- Body extends caudally between ventral sac of the rumen and the omasum lying toward the left of midline

- Pylorus is at the ventral end of 9th-10th intercostal space

What is the greater curvature of the abomasum attached to? The lesser curvature?

- Greater curvature is attached to the superficial layer of the greater omentum

- Lesser curvature is attache to the lesser omentum

Describe how the abomasum differs in the sheep/ox.

- The abomasum is relatively larger and longer than in the ox

What is the lateral, medial, dorsal, and ventral boundary of the epiploic foramen in the ruminant?

- Lateral: Caudate process of the liver

- Medial: Mesoduodenum and pancreas

- Dorsal: Caudal vena cava

- Ventral: Hepatoduodenal ligament

Where does the lesser omentum course in the ruminant?

- Courses between the abomasum and liver

What are the three compartments of the camelid stomach?

- Compartment 1: Cranial and caudal sacs

- Compartment 2

- Compartment 3

Describe compartment 1 of the camelid stomach.

- Largest compartment, holds 83% of contents, fermentation vat with saccules

Describe compartment 2 of the camelid stomach.

- Holds 6% of contents, mixing and fermentation with saccules

Describe compartment 3 of the camelid stomach.

- Holds 11% of contents; Initial 4/5 similar to the saccules of C1 and C2; distal 1/5 aids in acid secretion