The Pyloric Sphincteric Cylinder in Health and Disease

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Chapter 13 (page 53)


Narrow, circumferential indentations of the barium column appeared in the body of the stomach and proceeded to move in a caudal direction. Opposite the indentations the fine, flexible wires remained in their original position, showing that these indentations were due to contraction waves in the walls and not "falling together" of the walls. At a point 3.0 to 4.0 cm orally to the pyloric ring each wave became stationary, at the same time initiating a concentric, cylindrical narrowing of the barium column in the remaining part of the stomach, as far as and including the area of the ring. Again the wires were seen to remain in their original position. During a contraction the space between the wires and the luminal barium widened to approximately 8.0 to 10.0 mm all round, indicating an active, tube-like or cylindrical contraction of the muscular walls, 3.0 to 4.0 cm in length (Fig. 13.3). After a second or two of maximal contraction, the walls relaxed and the cycle was repeated.

On completion of the radiological examination the wires were removed by gentle traction on their external ends. None of the patients suffered any discomfort or untoward sequelae; recovery was normal.


It is concluded that the narrowing of the intraluminal barium column was not due to a passive falling together of the walls, as the fine, flexible wires on the serosal surface remained in their original positions. The narrowing of the column was due to active contraction of the walls between the serosa and the barium containing lumen. (Endoscopic ultrasonography confirms that "peristaltic" contraction of the wall produces wall thickening, as mentioned in Chapter 10).

Motor Divisions of Stomach

According to Code and Carlson (l968) the stomach has 3 functional regions corresponding to its anatomic divisions, namely the fundus, corpus and pyloric antrum, which, in their view, is the region stretching from the incisura angularis to the pylorus. (Comment: While the concept of these "anatomical" divisions appears to be widely accepted, it is shown in Chapters 2 and 3 that the division is of an arbitrary nature and not based on anatomical facts). In terms of motor activity Code and Carlson (l968) divided the antrum into two segments of varying length. The caudal portion participates in a simultaneous segmental contraction called the terminal antral contraction (TAC), previously described by Carlson, Code and Nelson (l966). The cephalad portion of the antrum, according to these authors, is not usually involved in TAC; however, at times TAC involves only the distal one to two centimeters of the antrum, and at other times almost the entire antrum. During TAC a simultaneous contraction of the terminal segment of the antrum occurs, a phenomenon which corresponds to antral systole previously described by Golden (l937). The cephalad and terminal (or caudal) segments of the antrum, together with the pylorus (also called the pyloric canal or pyloric sphincter) constitute a functional motor unit according to Code and Carlson (1968); the separate parts vary in their dimensions but contract in a co-ordinated way. The pyloric canal closes vigorously with contraction of the terminal antrum. (Comment: According to these authors the pyloric ring constitutes the pyloric sphincter. The pyloric canal is equated with the aperture).

Ruch and Patton (l973) state that morphologically, histologically and functionally the stomach is divided into 3 parts, viz. the fundus, corpus and pyloric antrum or pars pylorus, a narrower, more muscular, non-acid secreting region. The fundus and corpus together form a somewhat bulbous, thin-walled storage and secretory chamber, while food is fragmented and mixed with digestive juices in the "antrum". There is no structural discontinuity between these regions, which are only modifications of a basic pattern.

From the point of view of motility, other authors divided the stomach into two parts, namely a proximal one third and a distal two thirds (Kelly l98l; Funch-Jensen l987). The division was said to be based not on the usually accepted anatomical considerations, but on the type of smooth muscle activity. During swallowing the proximal part of the stomach relaxes, which allows filling without a significant increase in pressure. It acts as a receptacle and determines to a large extent the emptying of liquids. The distal two thirds shows active peristalsis which propagate luminal contents towards the pylorus, thereby effecting the emptying of solids.

In terms of motor function, based on the muscular anatomy, radiologically visible contraction patterns, manometrically recordable pressure waves and myoelectric activity, it is our view that the stomach should be divided into three parts namely (1) the fornix, (2) the corpus and sinus and (3) the distal 3.0 to 4.0 cm (Keet l957) (Fig. 13.4).

Fig. 13.4. In terms of motor activity the stomach should be divided into three parts. 1., fornix; 2., corpus and sinus; 3., distal 3-4 cm

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