Anatomy II: Lesson 7 DIGESTIVE SYSTEM

OBJECTIVE: STUDENTS WILL INVESTIGATE THE DIGESTIVE SYSTEM

IN ORDER IDENTIFY THE ANATOMICAL STRUCTURES OF THE

ESOPHAGUS, STOMACH, AND INTESTINES OF THE DOG.

Warm Up:

Fill in the blanks for the

following deciduous

or permanent

dentition and their specie variants

Esophagus

Connection between the

Oropharynx and Stomach

Esophagus Divisions

Pars Cervicis

Pars Thoracicia

Pars Abdominalis

Flexures of Esophagus

1. At C3, turns to the left of the

trachea

2. At C6 (thoracic inlet) returns to

normal position

3. At heart, turns dorsally

A. Pars Cervicis

B. Pars Thoracica

C. Diaphragm

D. Pars Abdominalis

E. M. Cardiac sphincter

F. Trachea

G. Heart

H. M. Phrenica & Hiatus Esophagi

SPECIE VARIANTS

In Eq and Ru, the

esophagus narrows

at thoracic inlet

and hiatus of

diaphragm

Components of

the Stomach

Stomach is interposed between the

esophagus and small intestine.

Muscular layer forms the cardiac

sphincter, where the esophagus joins

the stomach.

Successive contraction of the

muscular layers cause peristaltic

waves, which propel food from the

pharynx to the stomach.

Anti- perstaltic contractions are

responsible for the regurgitation in

ruminants and vomiting in other

domestic mammals

Types of Stomachs

Simple Glandular Stomach

Cats and Dogs

Lined with glandular mucosa

Simple Composite Stomach

Pigs and Equine

Mostly glandular but cranial

part has non-glandular

Complex Composite Stomach

Rumen (NG)

Reticulum (NG)

Omasum (NG)

Abomasum (G)

Components of the Stomach

Cardiac Portion (pars cardiaca)

Fundus (fundus ventriculi)

Body (Corpus ventriculi)

Pyloric Portion (pars pylorica)

Incisura Angularis

Forms plica angularis

Pronounced in Eq - incisura gastrica

Greater Curvature

Convex ventral border

Lesser Curvature

Concave dorsal border

Connected to liver by lesser omentum

Components of the Stomach Facies Parietalis

Surface adjacent to diaphragm and liver

Facies Visceralis

Surface in contact with organs

Ligaments of Stomach

Canine

Stomach

Simple Glandular

Pig Stomach

Simple Composite Stomach

Mixed glandular and

nonglandular

Ventricular Diverticulum

Torus Pylorus (only Ru and Sus)

Equine

Stomach

• Saccus caecus

• Margo plicatus

•(mixed region)

• Incisura gastrica

Blood Supply

of Stomach

A. Coeliaca

A. Gastrica sinistra

A. Lienalis (splenic)

A. gastroepiploic sin.

A. Hepatica

A. Gastrica dextra

A. Cranial Pancreaticoduodenal

A. Gastroepiploic dext.