Surface anatomy of the Stomach

The cardiac orifice is opposite the 7th left costal cartilage about 2.5 cm. from the side of the sternum; it corresponds to the level of the tenth thoracic vertebra.
The pyloric orifice is on the transpyloric line about 1 cm. to the right of the middle line, or alternately 5 cm. below the 7th right sternocostal articulation; it is at the level of the first lumbar vertebra.
A curved line, convex downward and to the left, joining these points indicates the lesser curvature. In the left lateral line the fundus of the stomach reaches as high as the 5th interspace or the 6th costal cartilage, a little below the apex of the heart.

To indicate the greater curvature a curved line is drawn from the cardiac orifice to the summit of the fundus, thence downward and to the left, finally turning medialward to the pyloric orifice, but passing, on its way, through the intersection of the left lateral with the transpyloric line. The portion of the stomach which is in contact with the abdominal wall can be represented roughly by a triangular area the base of which is formed by a line drawn from the tip of the 10th left costal cartilage to the tip of the 9th right cartilage, and the sides by two lines drawn from the end of the 8th left costal cartilage to the ends of the base line.

Note That: This measurements given refer to a moderately filled stomach with the body in the supine position !!!  Why we say that.........
As The shape of the stomach is constantly undergoing alteration; it is affected by the particular phase of the process of gastric digestion, by the state of the surrounding viscera, and by the amount and character of its contents. Its position also varies with that of the body.

With the patient in the erect posture.

With the patient lying down.