When the stomach is moderately full, most of it is located in the left quarter of the ribs. The cardia is located on the left side of the 11th thoracic vertebral body, and the pylorus is near the right side of the 1st lumbar vertebra. The anterior wall of the stomach is close to the left lobe of the liver on the right side and adjacent to the diaphragm on the left side and is obscured by the left costal arch. The part of the subxiphoid process not covered by the costal arch is in direct contact with the anterior abdominal wall and is therefore often used as a palpation site for the stomach.

The posterior wall of the stomach is adjacent to the left kidney, left adrenal gland, pancreas, spleen and other organs. The base of the stomach is near the left dome of the diaphragm and the spleen. The position of the stomach often varies greatly depending on the body type, position, and filling of the stomach contents, etc. The position of the stomach is higher in short and fat people and lower in long and thin people. When supine, the position of the stomach moves upward, and when upright, in addition to the cardia position is basically fixed, the great curvature of the stomach can reach down to the iliac spine plane or even lower.

Expanded:

The shape of the stomach is related to the body shape of the animal: fish, caudate amphibians, and snakes, because of their elongated bodies, have fusiform stomachs, while mammals, because of their stubby bodies, have stomachs that are curved in the form of a pouch and lie horizontally in the abdominal cavity.

In addition, the form and structure of the stomach can change depending on the need to store food, the nature of the food, and the frequency of ingestion. In primates, most carnivores, and many insectivores, the stomach tends to be a single-chambered organ with an anterior connection to the esophagus called the cardia and a posterior connection to the duodenum called the pylorus.

The part of the stomach near the cardia is called the cardia, the part near the pylorus is called the pylorus or pyloric sinus, and the middle part of these two is called the body of the stomach. In ruminants (cattle, goats, and sheep) the stomach is divided into four chambers called the rumen, reticulum, valvular stomach, and rumen (see ruminant stomach).

The esophagus of birds expands into a crop at the level of the clavicle. The crop is thin-walled, the inner surface is covered by a complex layer of squamous epithelium, the presence of digestive enzymes secreted by the esophagus and salivary glands, the crop has a function similar to that of the stomach, which can store food and carry out the preliminary digestion of food.