Anatomy of the Equine Gastrointestinal System (Part 2) - Dr. Masty

Two surfaces of the liver

1.) diaphragmatic

2.) visceral

diaphragmatic surface of the liver

cranial surface of the liver that lies against the diaphragm

visceral surface of the liver

caudal surface of the liver that lies against the intestinal segments

Five lobes of the equine liver

1.) left lateral

2.) left medial

3.) qudrate

4.) right

5.) caudate process

True or false: unlike the dog, the horse liver does not have a caudate lobe

true! only has caudate process located on the right visceral surface of the liver

Three ligaments of the liver:

1.) right and left triangular

2.) falciform ligament

3.) coronary ligament

right and left triangular ligaments

anchors liver to the body wall

falciform ligament

contains the round ligament of the liver, a fetal remnant of the umbilical vein

The falciform ligament pases between what two liver lobes?

left medial and quadrate

coronary ligament

remnant of the central tendon of the diaphragm; attaches the liver to the diaphragm

the coronary ligament surrounds what vessel?

caudal vena cava

Hepatic veins

emoty into the caudal vena cava from the liver

Porta

topographic central region on the visceral surface of the liver

Three components of the porta

1.) portal vein

2.) hepatic artery

3.) hepatic duct

Lymph nodes of the liver

variable and located in the porta area

Epiploic foramen

connection of omental bursa and peritoneal cavity

Dorsal boundary of the epiploic foramen:

-tissue structure:

-vascular structure:

-tissue structure: caudate process of the liver

-vascular structure: caudal vena cava

Ventral boundary of the epiploic foramen:

-tissue structure:

-vascular structure:

-tissue structure: pancreas

-vascular structure: portal vein

The spleen has two parts:

1.) base

2.) apex

base of the spleen

broad part of the spleen located dorsally

apex of the spleen

pointy end of the spleen located ventrally

The stomach has three parts:

1.) fundus

2.) body

3.) pyloric part

the fundus is aka...

the blind sac; projects dorsally towards the esophagus

margo plicatus

line that separates the glandular and squamous mucosa of the stomach

Three reasons horses cannot vomit:

1.) strong cardiac sphincter

2.) acute angle of entry of the esophagus

3.) fold of mucosa that covers the cardia (entrance to the esophagus)

The greater omentum attaches to the _________ curvature of the stomach

The lesser omentum attachs to the _________ curvature of the stomach

greater

lesser

Two ligaments of lesser omentum

1.) hepatoduodenal ligament

2.) hepatogastric ligament

hepatoduodenal ligament

portion of the lesser omentum passing from the liver to the duodenum

The hepatoduodenal ligament also contains the...

strucutres of the porta

hepatogastric ligament

portion of the lesser omentum passing from the liver the stomach

Three parts of the pancreas:

1.) right lobe

2.) body

3.) left lobe

the right lobe of the pancreas faces the....

duodenum

the left lobe of the pancreas faces the....

stomach

Two ducts of the pancreas:

1.) pancreatic duct

2.) accessory duct

pancreatic duct of the pancreas

opens on the major duodenal papilla

major duodenal papilla

opening of the pancreatic duct into the duodenum

accessory duct of the pancreas

opens on the minor duodenal papilla

minor duodenal papilla

exit for pancreatic juice coming through the accessory pancreatic duct

What vein enters the pancreas?

portal vein

Pancreatic ring

passage for the portal vein through the body of the pancreas

Six parts of the duodenum:

1.) cranial part

2.) cranial duodenal flexure

3.) descending duodenum

4.) caudal duodenal flexure

5.) ascending duodenum

6.) duodenojejunal flexure

cranial part of the duodenum

part of the duodenum leaving the pylorus

cranial duodenal flexure

first bend of the duodneum near pylorus

descending duodenum

section of duodenum coursing caudally

caudal duodenal flexure

transverse part of the duodenum

the caudal duodenal flexure is located __________ to the root of the mesentery

caudal

ascending duodenum

section of duodenum coursing cranially

duodenojejunal flexure

the junction between the duodenum and jejunum

The major duodenal papilla has two structures opening on it:

1.) pancreatic duct

2.) hepatic duct

The minor duodenal papilla has one structure opening on it:

accessory pancreatic duct

The jejunum has a pronouced _________ arcade

vascular

The walls of the jejunum are...

smooth; no bands present

Three features of the ileum:

1.) ileocecal fold

2.) ileal papilla

3.) ileocecal orifice

ileocecal fold

fold of connecting peritoneum between the cecum and ileum

the ileocecal fold indicates the ________ part of the small intestine

terminal

ileal papilla

projection at the end of the ileum as it goes past the wall of the cecum

the ileal papilla is located on the ________ wall of the cecum

medial

ileoceceal orifice

the opening of the ileal papilla into the cecum

What is special about the sphincter in the ileoceceal orifice?

it is very vascular, unlike most other sphincters in the body

Three parts of the cecum:

1.) base

2.) body

3.) apex

base of the cecum is located...

in the right paralumbar fossa

body of the cecum is located...

in the caudal part of the right flank

apex of the cecum is located...

close to the xiphoid process near the midline

cecocolic ligament

Attaches cecum to right ventral colon

cecocolic orifice

opening between the cecum and right ventral colon

The transverse colon is about ____ inches in length

4

How can you tell the difference between the descending colon and small intestine?

the descending colon will have bands and sacs

Teniae coli

commonly known as bands

the cecum has _______ bands

4 bands

the right ventral colon has _________ bands

4 bands

the left ventral colon has _________ bands

4 bands

the left dorsal colon has _________ bands

1 band

the right dorsal colon has _________ bands

3 bands

the transverse colon has _________ bands

variable

The small colon has __________ bands

2 bands

Haustra

commonly known as sacs; pouches of the large intestine that allow expansion and elongation

Obstruction sites in the GI tract can be due to two factors:

1.) anatomic factors

2.) physiologic factors

Two anatomic factors for GI tract obstruction:

1.) due to decrease in luminal diameter in the tract

2.) due to strong flexure of the tract that occurs at the cecocolic oriface

a decrease in the luminal diameter takes place in two areas:

1.) pelvic flexure

2.) right dorsal colon to transverse colon

One physiologic factor for GI tract obstruction:

intussesception

intussesception

telescoping of a segment of the intestine

an intussesception can occur most commonly at the level of the...

ileocecal junction

Three main arteries of the gastrointestinal system:

1.) celiac artery

2.) cranial mesenteric artery

3.) caudal mesenteric artery

The celiac artery has three branches:

1.) splenic

2.) left gastric

3.) hepatic

splenic artery supplies...

the spleen

left gastric artery supplies...

the lesser curvature of the stomach

hepatic artery supplies...

the liver

Eight branches of the cranial mesenteric artery:

1.) caudal pancreaticoduodenal

2.) jejunal

3.) middle colic

4.) right colic

5.) ileocolic

6.) colic branch of the ileocolic

7.) lateral and medial cecal

8.) ileal

The cranial mesenteric artery branches can be broken up by three areas of the tract it supplies:

1.) small intestine

2.) colon

3.) cecum

Three branches of the cranial mesenteric artery that supply the small intestine:

1.) caudal pancreaticoduodenal

2.) jejunal

3.) ileal

caudal pancreaticoduodenal artery supplies..

the duodeunm

jejunal artery supplies..

the jejunum

ileal artery supplies...

mesenteric side of the ileum

the ileal artery will anastome with...

ileocolic artery

Four branches of the cranial mesenteric artery that supply the colon:

1.) middle colic

2.) right colic

3.) ileocolic

4.) colic branch of the ileocolic

middle colic artery supplies..

transverse colon

the middle colic artery will anastomose with...

left colic artery

right colic artery supplies..

left and right dorsal colon

after the right colic artery branches off, the cranial mesenteric artery changes names to the...

ileocolic artery

the ileocolic artery will anastomose with...

ileal artery