Download The stomach (gaster)

The stomach (gaster)
The stomach (gaster): is the large dilation of the alimentary canal caudal to the diaphragm which
located between the esophagus and the small intestine. It stores food temporarily and digests it
chemically.
Classification of the stomach:
1-According to the number of cavities:
A-monolocular stomach: it is contains one cavity like in dog, horse, pig and all animals except
ruminants.
B-multilocular stomach: it is contain many cavities like in ruminants (ox, goats and sheep).
2-according to the mucous membrane lining (inner lining):
A-simple stomach: it lines by one kind of mucous membrane (glandular mucosa), covered by simple
columnar epithelium like dog, cat and man.
B-compound stomach: it lines by glandular and non glandular mucosa like in ruminants, pig and
horse.
♣ The part which lines by non glandular mucous membrane called forstomach or proventriculus
which differ in size from small zone around cardia in the pig to large part in horse or three large
cavities in ruminants called the rumen, reticulum and omasum
The glandular part in the ruminants is a separate cavity the abomasums.
Stomach of horse:
1-it is monolocular compound stomach.
2-it is sharply curved, J-shaped sac, the right part
being very much shorter than the left.
The convexity is directed ventrally. It has two
surface, two curvature and two extremities.
1-the parietal surface: it is convex and directed
cranial, dorsal and to wards the left. It lies against the
diaphragm and liver.
2-the visceral surface: also convex, it is related to the
terminal part of the large colon, pancreas, small
intestine and the greater omentum.
♣ The border between two surfaces are termed the
curvature.
♣ The lesser curvature is very short extending from the termination of esophagus to the junction with
small intestine.
♣ The greater curvature is very thick, extending from the cardiac; its first directed dorsally and
curves over the left extremity.
It is then descends, passes to the right crosses the median plane and curves dorsal to end at the
pylorus.
♣ The left extremity: has the form of round cul-de-sac termed the saccus caecus ventriculi. It lies
ventral to the left crus of the diaphragm and it is related to the pancreas and the termination of the
great colon caudally and the base of spleen laterally.
♣ The mucous coat is clearly divided into two parts:
1-non glandular part: lines the greater parts of the left sac resemble to esophagus mucous
membrane and it is termed the proventicular part (esophageal region). It is white in color.
2-glandular part: it contains the gastric glands and sub divided into three zones according to the
types of glands which it contains:
A-cardiac gland region: narrow a zone along the greater curvature has yellowish gray color and
contains cardiac gland.
B-fundus gland region: next to cardiac gland region is a large area which has a mottled, a reddish
brown color and contains fundus gland.
C-pyloric gland region: is much smaller and has a reddish gray or yellowish gray color and contains
pyloric glands. It is continuous with the duodenum, the junction between it and duodenum indicated
by a marked constriction.
♣ There are two orifices:
A-cardiac orifice between the stomach and esophagus, in this opening there are numerous folds
which occlude the opening. It is terminated by abruptly, forming an irregular sinus raised edge
termed margoplicatus which separate the cardiac region from the non glandular region.
B-pyloric orifice: called pylorus, is the opening into the intestine, is indicated externally by distinct
constriction, internally it presents a circular ridge caused by a ring of muscular tissue (pyloric
sphincter).
Fixation of stomach:
1-pressure of adjacent organs.
2-blood vessels supplying. -branches of the celiac artery. -gastric
veins.
3-esophagus.
4-doudenum.
5-greater omentum connects the ventral part of the greater curvature and the first curve of the
duodenum with the terminal part of the great colon and the initial part of the small colon.
6-lesser omentum connects the lesser curvature and the first part of the duodenum with liver ventral
to the esophageal impression and portal fissure, it divided into two parts:
A-the hepatodoudenal ligament the remainder of the omentum which goes to the duodenum.
B-the hepatogastric ligament extends from the liver to the stomach.
7-gastrophrenic ligament connects the greater curvature from the cardia to the left extremity with the
crurae of the diaphragm.
8-gastrosplenic ligament passes from the left part of the greater curvature to the hilus of the spleen.
It’s continuous with the greater omentum.
9-gastropancreatic fold extends from the left sac dorsally to the cardia to the duodenum. It’s attached
dorsally to the liver and caudal vena cava, ventrally to the pancreas.