Canine Gastrointestinal System Anatomy

What is the peritoneum?

Serous membrane that lines the abdominal cavity and envelops the abdominal organs.

What are the types of peritoneum?

Visceral, parietal and connecting.

What does the parietal peritoneum line?

Abdominal wall.

What does the visceral peritoneum line?

Abdominal organs.

What does the mesentery peritoneum connect?

Bowel to body wall.

What does the omentum peritoneum connect?

Stomach to another structure (e.g. body wall).

What does the fold peritoneum connect?

Bowel to bowel or another organ.

What does the ligament peritoneum connect?

Non-bowel to another structure.

Describe how the diaphragm relates to the abdomen

Separates the thorax from the abdomen with the aortic hiatus, oesophageal hiatus and the caval foramen as the main connections between the two.

Where is the aortic hiatus and state its significance

Found between left and right crura, allows aorta to pass from thorax into the abdomen.

Where is the oesophageal hiatus and state its significance

Located in the right crus of abdomen, in the muscular part at the level of T10. Allows oesophagus to pass from thorax into abdomen.

Where is the caval foramen and state its significance

In the central tendon of the diaphragm and allows the caudal vena cava to enter the abdomen from the thorax.

What is the function of the liver?

Filters blood and secretes bile.

What is the function of the stomach?

Digests food.

What is the omental bursa?

Potential space created by the greater omentum.

What is the function of the spleen?

Blood reservior

What is the function of the duodenum?

For further digestion of food, absorbing nutrients and water.

What is the function of the pancreas?

Exocrine functions for digestion, endocrine function to regulate blood sugar.

What is the function of the jejunum?

Aids in food digestion, absorbing nutrients and water.

What is the function of the ileum?

Aids in food digestion, absorbing nutrients and water.

What is the function of the caecum?

Absorbs fluids and salts remaining in the GI post-ileum. Also mixes anything it cant absorb with lubricating mucus.

What is the function of the colon?

Removes water and salts and some nutrients from partially digested food.

What is the function of the rectum?

Stores solid waste (faecal material).

What is the main difference between the abdominal cavity and the peritoneal cavity?

The abdominal cavity contains all the abdominal organs including the peritoneum. The peritoneum lines the abdominal cavity and abdominal organs.

What is the abdominal cavity defined by?

Abdominal wall laterally, diaphragm cranially, linea alba ventrally.

Describe the topographical anatomy of the diaphragm

Attaches to body wall at the level of the last rib. Extends into the thorax to level of the 5th intercostal space.

State the lobes of the liver

Left and right (medial and later in dog)

Caudate (with caudate and papillary processes)

Quadrate.

What are the main ducts that lead to the gall bladder?

Cystic, hepatic, common bile.

What are the main regions of the stomach?

Fundus (blind-ending), corpus (aka body), pylorus (exit of stomach).

Describe the topographical anatomy of the spleen

On the left hand side of the abdomen.

Describe the topographical anatomy of the duodenum

First part of the small intestine.

Where do the bile and pancreatic duct exit in the duodenum?

Major duodenal papilla.

Where does the accessory pancreatic duct exit in the duodenum?

Minor duodenal papilla.

Where in general do ducts from the liver empty their secretions?

Cranial end of the duodenum.

State the lobes of the pancreas

Left and right lobes.

State the direction that the left lobe of the pancreas travels in

Medio-lateral direction.

State the direction that the right lobe of the pancreas travels in

Cranio-caudal direction.

Describe the topographical anatomy of the jejunum

Middle part of intestine, covered by the greater omentum.

Describe the topographical anatomy of the ileum

Terminal portion of the small intestine, enters the large intestine at the caeco-colic junction. Characterised by having parallel-running blood vessels.

Describe the topographical anatomy of the caecum

First part of the large intestine. In dogs, the ileum runs directly into colon with caecum attached on the side. This is different to some other species where the caecum is continuous with the colon, and the ileum enters the large intestine at the caeco-colic junction.

Describe the pathway of the colon

Ascending (right) -> right colic flexure -> transverse (passes cranial to root of mesentery) -> left colic flexure -> Descending (left) -> meets rectum in midline.

State the peritoneal attachments of the liver and where they hold it to

Coronary ligament, right and left triangular ligaments, falciform/round ligament. Hold the liver tightly to the diaphragm. Lesser omentum holds liver closely to stomach.

State the peritoneal attachments of the stomach and where they hold it to

Greater omentum - stomach to body wall

Lesser omentum - stomach to liver

Gastro-splenic ligament - stomach to spleen

State the peritoneal attachments of the spleen and where they hold it to

Gastro-splenic ligaments - spleen to stomach

State the peritoneal attachments of the duodenum and where they hold it to

Mesoduodenum - bowel to body wall

Duodeno-colic fold - duodenum to colon

Hepato-duodenal ligament - Liver to duodenum

State the peritoneal attachments of the pancreas and where they hold it to

Right lobe is within mesoduodenum

Left lobe is within deep leaf of greater omentum

State the peritoneal attachments of the jejunum and where they hold it to

Meso-jejunum (AKA mesentery) - jejunum to dorsal body wall.

State the peritoneal attachments of the ileum and where they hold it to

Ileo-caecal fold - ileum to caecum

Meso-ileum (extension of the meso-duodenum) - ileum to body wall

State the peritoneal attachments of the caecum and where they hold it to

Ileo-caecal fold - ileum to caecum

Caeco-colic fold - caecum to colon

State the peritoneal attachments of the colon and where they hold it to

Meso-colon - colon to dorsal body wall.