The author has compared the roentgenologic findings of the stomach with the structure and function of its tunica muscularis. Physiologists, previously, have observed that the stomach as to the muscular activity consists of two parts with different characteristics on each side of the angulus. The muscular activity in a normal stomach is well coordinated from the cardia down to the pylorus. The roentgenologic studies, however, have been concentrated on the appearence of the muscular activity in cases with ulcer in each part, in the longitudinal stomach and at the incisura angularis, giving principally different roentgenologic pictures of the shape and mucosal folding. In this way it has been possible to observe the activity of the strong bundles of the suspensory sling in the longitudinal stomach, limited to this part and unique in the whole digestive tract. In recent years physiologic investigations have added valuable information about the muscular function of the stomach, briefly reported in this paper. Electrogastrograms have confirmed that the function, normally synchronized, under certain conditions can show a dissociation of the two parts. Experimental investigations have shown that the autonomic nervous have shown that the autonomic nervous has an important function for the stomach as a reservoir-organ. Beside the earlier known mode of activity of this system, the vagus is mediating a reflex without any known transmittor substance, this vagal reflex also indicating a different activity between the two parts of the stomach.