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Chapter 15 (page 75)
Many authors failed to find evidence of a tonically contracted ring structure at the
pylorus. Atkinson et al. (l957) were unable to demonstrate independent contraction of
the pyloric ring; they found that the pylorus was normally relaxed and did not act
antagonistically to phasic pressure waves. Andersson and Grossman (l965), Kaye et al.
(l976), McShane et al. (l980), White et al. (l98l), Dooley et al. (l985) and Gaffney et al.
(l987) found no convincing manometric evidence of a zone of tonically elevated basal
pressure at the pylorus. McShane et al. (l980) stated that the pyloric sphincter remained
patent under fasting conditions. Apart from a brief closure during contraction, the
pylorus was always open, according to White et al. (l98l). Kelly (l983) and Gaffney et al.
(l987) concluded that the evidence weighed heavily against the presence of a tonic
sphincter at the pylorus.
Winans (l976) attributed the divergent results of manometric studies to differences in
methodology and differences in position of the subjects examined. Whereas the human
pylorus was easily identifiable as a gross anatomic structure, it eluded identification as a
functioning sphincter. Winans (l976) called this a "sphincteric paradox", and referred to
the pylorus as being "fickle". Adding to the confusion is the lack of agreement on the
definition of a sphincter (Chap. 2) and its relation to a high pressure zone.
In determining the manometric features of the pylorus, none of the authors quoted, with
the exception of Keet et al. (l978), referred to or took note of the muscular anatomy of the
region as determined by Cunningham (l906), Forssell (l913) and Torgersen (l942) (Chap.
3). According to this concept the pyloric ring consists of an aboral thickening of the
cylinder, and constitutes an inherent part of the cylinder both anatomically and
functionally. The closest any of the authors came to the concept of a sphincteric cylinder
at the pylorus, was the recognition of the "terminal antrum" as a functional unit by
Carlson, Code and Nelson (l966), Code and Carlson (l968) and Shepard (l97l). However,
the terminal antrum had not been defined in terms of muscular anatomy, whereas the
sphincteric cylinder had.
The sphincteric mechanism at the pylorus will probably prove to be less paradoxical once
the muscular component of the pyloric ring (the right pyloric loop) is no longer regarded
as a separate structure, but is acknowledged to be an inherent part (i.e. the aboral end) of
the pyloric sphincteric cylinder.
- Andersson S, Grossman MI. Profile of pH, pressure, and potential difference at
gastroduodenal junction in man. Gastroenterology l965, 49, 364-371.
- Atkinson M, Edwards DAW, Honour AJ, et al. Comparison of cardiac and
pyloric sphincters. Lancet l957, 273, 918-922.
- Brink BM, Schlegel JF, Code CF. The pressure profile of the gastroduodenal
junctional zone in dogs. Gut l965, 6, 163-171.
- Carlson HC, Code CF, Nelson RA. Motor action of the canine gastroduodenal
junction: a cineradiographic, pressure and electric study. Amer J Dig
Dis l966, 11, 155-172.
- Code CF, Carlson HC. Motor activity of the stomach. In: Handbook of
Physiology, Sect 6: Alimentary Canal, Vol 4: Motility. American
Physiological Soc, Washington DC l968, pp 1903-1906.
- Cunningham DJ. The varying form of the stomach in man and the anthropoid
ape. Trans Roy Soc Edin l906, 45, 9-47.
- Dent JA. A new technique for continuous sphincter pressure measurement.
Gastroenterology l976, 7l, 263-267.
- Dooley CP, Reznick JB, Valenzuela JE. A continuous manometric study of the
human pylorus. Gastroenterology l985, 89, 821-826.
- Fisher RS, Cohen S. Physiological characteristics of the human pyloric sphincter.
Gastroenterology l973, 64, 67-75.
- Forssell G. Über die Beziehung der Röntgenbilder des menschlichen
Magens zu seinem anatomischen Bau. Fortschr Geb
Röntgenstr 1913, Suppl 30, 1-265.
- Gaffney PR, Gleeson DJ, Hall JW, et al. The manometric findings at the human
pylorus: the evidence against the presence of a tonic sphincter. Scand J
Gastroenterol l987, 22, 525-532.
- Houghton LA, Read NW, Heddle R, et al. Motor activity of the gastric antrum,
pylorus and duodenum under fasted conditions and after a liquid meal.
Gastroenterology l988, 94, 1276-1284.
- Houghton LA, Read NW, Heddle R, et al. Relationship of the motor activity of
the antrum, pylorus and duodenum to gastric emptying of a solid-liquid mixed
meal. Gastroenterology l988, 94, 1285-1291.
- Isenberg JI, Csendes A. Effect of octapeptide of cholecystokinin on canine
pyloric pressure. Amer J Physiol l972, 222, 428-431.
- Kaye MD, Mehta SJ, Showalter JP. Manometric studies of the human pylorus.
Gastroenterology l976, 70, 477-480.
- Keet AD, Vermaak JC, Mouton J. Intraluminal pressure profiles and mucosal
movements in the stomach and duodenum. Amer J Gastroenterol
l978, 69, 144-148.
- Kelly KA. Motility of the stomach and gastroduodenal junction. In:
Physiology of the Gastrointestinal Tract. Vol 1, Edit Johnson LR.
Raven Press, New York l98l, pp 393-410.
- McShane AJ, O'Morain C, Lennon JR, et al. Atraumatic non-distorting pyloric
sphincter pressure studies. Gut l980, 21, 826-828.
- Shepard RS. Human Physiology. JB Lippincott Co, Philadelphia
l97l, p 417.
- Torgersen J. The muscular build and movements of the stomach and duodenal
bulb. Acta Rad l942, Suppl 45, 1-191.
- Valenzuela JE, Defilippi C, Csendes A. Manometric studies on the human
pyloric sphincter: effect of cigarette smoking, metoclopramide and atropine.
Gastroenterology l976, 70, 481-483.
- White CM, Poxon V, Alexander-Williams J. A study of motility of normal
human gastroduodenal region. Dig Dis Sci l98l, 26, 609-617.
- Winans CS. The fickle pylorus (editorial). Gastroenterology l976,
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