[Plate 293, Lymph Vessels and Nodes of Stomach]page 142
page 143J-shaped enlargement of the gastrointestinal tract
Chief function: enzymatic digestion
Acidic gastric secretions convert food into liquid chime
Passes fairly quickly into the duodenum
Parts of the stomach
Greater curvature: long, convex border
Lesser curvature: short, concave border
Cardia: surrounds cardial (esophageal) orifice
Fundus: dilated upper part
Above the level of the esophageal orifice
Dilated by fluid, food, but mainly gas
Separated from esophagus by cardiac notch
Body: between fundus and pyloric antrum
Pyloric part
Begins at level of angular incisure: indentation two thirds of the way along the lesser curvature
Widest region: pyloric antrum
Antrum leads to pyloric canal
Pylorus: surrounds pyloric orifice
Pyloric sphincter
a. Thick, circular middle layer of muscularis externa
b. Controls passage of chime into duodenum
c. Normally closed in tonic contraction, except during peristalsis
Three muscle layers: outer longitudinal, inner circular, and innermost oblique
Internal surface thrown into numerous longitudinal folds-rugae
Gastric canal = longitudinal fold along lesser curvature
Forms during swallowing
Accommodates the passage of liquid
Covered by peritoneum except where blood vessels run over it, and over a small area posterior to the cardiac orifice
Double layer of peritoneum extends between stomach and liver and duodenum and liver: lesser omentum
Two layers of lesser omentum wrap around stomach and leave greater curvature as great omentum