Naziha Sultan Ahmed, BVMS, MSc Scientific degree (Assis. Prof.), Department of College of Veterinary Medicine, University of Mosul, Mosul, Iraq https://orcid.org/0000-0002-2856-8277 https://www.researchgate.net/profile/Naziha_Ahmed Anatomy | Part 16| 2nd year 2019

Digestive System The have two lines: 1- anorectal line: mark the connection of the anal canal with the . 2-anocutaneus line: mark the connection of the anal canal with the skin. In horse: the opening of the anus present in the center of an elevation ventral to the root of tail. Anal canal lined with non-glandular mucosa. In dog: the mucosa of anal canal present three annular zones: 1-Columnar zone: dark zone contain anal glands. 2-Intermediate zone: narrow distinct area. 3-Cutaneus zone: lined by cornified epithelium with fine hairs and circumanal glands and the two laterally placed anal sacs.

*Anal sacs: small collateral reservoirs for a foul-smelling secretions of surrounding glands ,present in anal canal of dog. *The internal smooth anal sphincter (involuntary) and external striated (skeletal) anal sphincter (voluntary), both are present in all animals.

CouAnatomy | Digestive system | Assis. Prof. Naziha Sultan Ahmed Page | 1 Note: the anal sacs, which functions for territorial scent marking. The anal sacs are of considerable clinical importance, since they are commonly diseased in dog. They become frequently enlarged, due to accumulated secretion or may become abscessed and painful, causing constipation. Accessory glands associated with digestive system:

The : The larges gland in the body due to its function. Liver weight related reversally with the age and proportionally with the stored food. Liver color depend on the amount of blood, species, age. To study the lobation of the liver, we use imaginary lines as follow: 1-First line extend from esophageal notch present in dorsal border of liver to the notch of round ligament present in the ventral border , so we detect the left lobe. 2-Second line extend from caudal vena cava notch present in the dorsal border of the liver to the position of the gall bladder present in the ventral border, so, we detect the right lobe of the liver. 3-The remained part between right & left lobes called the middle lobe. 4-The hepatic porta divide the middle lobe of the liver into caudate lobe dorsally and quadrate lobe ventrally.

*Hepatic porta: is a depression present on the visceral surface of the liver through which the hepatic artery, portal vein, and hepatic ducts pass*.

The gall bladder: ductules are the roots of hepatic ducts which transmit the bile to the hepatic ducts, here, these ducts unite to form the , which unite in turn with the to form the , which pass through hepato-duodenal ligament (part of the lesser omentum) to open in the major duodenal papilla (open alone in cow and with the chief in horse, dog and small ruminants.

The gall bladder of the ruminants lies on the visceral surface of the liver extend ventrally to a distance more than the ventral border of liver. In dog : gall bladder can be seen from both visceral & parietal surfaces because the inter-lobar fissures are deep . *In horse : gall bladder is absent*.

CouAnatomy | Digestive system | Assis. Prof. Naziha Sultan Ahmed Page | 2

CouAnatomy | Digestive system | Assis. Prof. Naziha Sultan Ahmed Page | 3