POSTGRAD. MED. J.. (1966), 42, 301 Postgrad Med J: first published as 10.1136/pgmj.42.487.301 on 1 May 1966. Downloaded from CONTROL AT THE CARDIA RICHARD K. GREENWOOD, M.D., M.Chir., F.R.C.S.

Surgical Tutor *St. Thomas' Hospital Medical School, London, S.E.1.

DESPITE many recent advances, a thorough DIAPHRAGM understanding of the physiological action of the ilower segment of Ithe oesophagus is still incomplete. The precise location of the gastro- MUCOSAL JUNCIONI esophageal junction requires definition. Clearly CARDIAC ORIFICE it is where oesophagus terminates and commences. Unfortunately there is no unanimity of opinion on this matter. Barrett (1958) defines LOOP OF WILLI the oesophagus as the tubular structure inter- - % posed between the ph'arynx and ,bag of the stomach, receiving its blood supply from the aorta rather than ,the left gastric artery and having no peritoneal covering. This places the FIG. l.-Anatomy of the gastroesophageal junction. gastroesophageal junction at the level of the incisuria cardia where the fundus of the stomach phragmatic hiatus -to enter the abdomen. As commences (Ingelfinger 1958). The opening into copyright. the stomach is referred to as ,the cardiac orifice it does so it deviates -forwards and to the left. and the region immediately above it as the The oesophageal opening in the diaphragm is cardia. Earlier however Barrett (1950) had closed by the phreno-esophageal Imembrane. suggested that the mucosal junction offered a This is morphologically part of the transversailis convenient and distinct landmark between the fascia which 'lines the interior of the whole two organs. He and Palmer (1953) postulated abdominal cavity. It passes from the under- that anything lined with squamous epithelium surface of the diaphragm to the wall of the was oesophagus, and any structure with gastric oesophagus where it splits into ascending and glandular mucosa was stomach. The mucosal descending fibres which eventually merge with http://pmj.bmj.com/ junction however 'bears little relation to the t,he muscle in the walil. Anders land Bahrmann structure and function of the muscle. (1932) noted ,many elastic fibres in the mem- underlying brane, but its texture and significance are Anatomy of the Junction disputed. Allison .(1951), believes it to be a Gastroesophageal tough structure of considerable importance in The oesophagus of man is a tubular structure restraining 'the stomach within the a,bdomen. with a muscular wall. '(Fig. 1) The muscle is Barrett i(1954) however, considers ilt to ;be too arranged in two layers, an inner circular and delicate to play any part in preventing sliding on October 1, 2021 by guest. Protected an outer longitudinal. In the upper part of 'the hiatal herniation. organ the muscle is striated but in the midd,le The mucosal junction is clearly discernible third there is a gradual transition from striated on the inner aspect of the two organs. The to smooth, the lower end consisting entirely of stratilfied epithelium of -the oesophagus is white, smooth muscle (Arey and Tremaine, 1933). At the columnar mucosa of the stomach reddish the level of t,he cardiac orifice of the stomach brown. The two meet at an irregular but easiJly tlhe musdle !fibres in the wa,ll are arranged in a definable line. T'he precise location of the loop encompassing the anterior, lateral and columno-squamous junction in relation to both posterior aspects of the organ. These are the cardiac orifice of the stomach and the variously referred to as ,the loop of Willis (1674), diaphragm in the living human is disputed or collar of Helvitius. (Aillison and Johnstone, !1953; Palmer, 1953; The oesophagus -passes through the dia- Creamer, Harrison and 'Pierce, 1959). It is probable Ithat the lower 2 cm. of tubuilar "gullet" *Presen.t A'ddress: Leiceste'r General Hospital normally has a columnar lining and that the 302 POSTGRADUATE MEDICAL JOURNAL May, 1966 Postgrad Med J: first published as 10.1136/pgmj.42.487.301 on 1 May 1966. Downloaded from epithelial junction lies just Ibelow ,t,he oesopha- The first is that of a pinchcock action. This geal hiatus of the diaphragm. It is agreed hypothesis was put forward by Jackson (1922) that there may be variations in the precise who suggested a side-to-side compression bet- location from individual -to individual, and also ween the two pillars of the crus. This has possibly in the same individual from time to been noted at oesophagoscopy and could time owing to the muscular activity of the account for the hold-up at the level of the muscularis mucosa '(Palmer, 1953; Nauta, 1955; diaphragm sometimes noted during barium Alilison, 1956). In this connection it is interesting swallows (Johnstone, 1955). This pinchcock to note that the mucosal junction in the dog is action of the diaphragm is far from constant located at a sim,i'lar level to -that in man, at or and is observed only during inspiration- just below the oesophageal hiatus. In other Joannides (1929) postulated a milking action vertebrates, however, the junction may 'be high of the pillars of the crus on the walls of the in the oesophagus ,(bat) or low in the stomach oesophagus during inspiration. Dornhorst, (rat). ,(Botha, 1958b). Harrison and Pierce (1954) and Braasch and Ellis 1(1956) however, have been unable to Physiology of the Closing Mechanism at the detect any gripping action of the diaphragm Gastroesophageal Junction during inspiration. It is agreed by all who have studied the The other sphincteric action attributed to problem that some closing mechanism exists the diaphragm was propounded by Allison between the oesophagus and stomach which (1951). He likened the gastroesophageal junction prevents reflux of contents of the latter into the to the ano-rectal junction. In both sites t'he former. Essentiailly the hypotheses propounded alimentary canal changes direction and passes to laccount for gastroesophageal competence :through a muscular diaphragm ,(the diaphragm may be grouped under certain 'headings: and pubo-rectalis). It was postulated that the 1. The presence of a morphological sphincter. right crus of the diaphragm which lassoes the 2. Mechanical factors. cardilac angle and hitches it to the lumbar spine 3. The presence of an intrinsic physiological (Collis, Satchwel'l and Aibrams, 1954) mightcopyright. sphincter. compress the gastroesophageal junction directly or serve ito maintain the angle of entry of 1. Morphological Sphincter oesophagus into the stomach and enable this Two varieties of anatomical sphincter have to function as a mechanical flap valve (vide ,been considered as factors responsible for infra). closure of the gastroesophageal junction- intrinsic and extrinsic. 2. Mechanical Factors (a) Intrinsic. A constriction in the wall of t'he (a) Oblique entry into stomach. of oesophagus http://pmj.bmj.com/ lower human oesophagus near the gastro- The cardiac angle or angle of His (1903) has esophageal junction has been reported by a been considered an important antireflux factor number of workers. i(Laimer, 1883; Lerche, by many observers. When the angle is acute, 1950; Nauta, 1955). Most of the studies have distension of the stomach tends to close the been carried out on cadavers and accoun;ts of gastroesophageal junction in a valve-like fashion the relationship of the narrowing to the dia- by forcing the intrailuminal projection created by phragmatic 'hiatus have 'varied. The cause of the the angle against the opposite oesophageal wall narrowing has been reported as a localised (Von Gubaroff, 1886; Dick and Hurst, 1942 and on October 1, 2021 by guest. Protected muscle thickening. (Hurst, 1925; Anders and Barrett, 1954). Marchand (1955) ;believed that Bahrmann, 1932; Lerche, 1950). Other the cardiac angle acted purely mechanically and investigators have ibeen unable to con'firm was a passive phenomenon. He demonstrated these findings '(Lendrum, 1937; IPeters, 1955) that the cardia was competent in the cadaver and most authorities now agree that there is provided that -the angle of His was not oblite- no morphological sphincter in the wall of the rated. This work has not been substantiated, human oesophagus. It is interesting -to note however, and it is difficult to see how the angle however that such anatomical sphincters do can form 'an effective ,barrier uniless it is main- exist in certain species, e.g., the bat. (Fischer, tained by some active means. Many believe that 1909). the diaphragm fulfills this role, and certainly (b) Extrinsic. It has been suggested thTt the the angle is lost in the presence of a hiatal diaphragm might act as an external sphincter hernia. Smiddy and Atkinson (1960) however upon the lower oesophagus. Two mechanisms showed that Ithe angle persisted after the gastro- have been postulated in this connection. esophageal junction had ibeen completely freed Postgrad Med J: first published as 10.1136/pgmj.42.487.301 on 1 May 1966. Downloaded from May, 1966 GREENWOOD: Control at the Cardia 303 from the d,iaphragm. They believe ithat the is greater than intragastric pressure and hence oblique 'fibres constituting the loop of Willis the segment remains closed. (Cannon, 191i1; maintain the oesophago-gastric angle by acting Fyke, Code and Schlegel, 1956). It has been as a sling around the cardia. Disruption of the suggested that individuals without an intra- oblique fibres of the gastric muscle coat on the aWbdominal oesophagus are particula,rly sus- lateral side of the cardia renders Ithe latter more ceptible to gastroesophageal reflux when intra- susceptible -to reflux. Similar results were re- abdominal pressure is increased (Wolf, 1960). ported by Gahagan '(1962). It is possible that the distance separating the It 'is interesting to note however that the diaphragmatic hiatus and cardiac orifice may cardiac angle is a 'late evolutional development, vary and factors wYhich shorten this distance being present only in reptiles and mammals may facilitaate retrograde flow, e.g., pregnancy (Botha, 1958b). It is possilble therefore *that (Nagler and Spiro, 1961). the distribution of the sling fibres along the lesser curva,ture of the stomach may be a result 3. Intrinsic Physiological Sphincter of the angle rather than its cause as certain In recent times 'progressively more attention lower animals have an incisura but no sling has been directed to the possibility of a phy- fibres. siologicall sphincter existing between the oeso- ;(b) Mucosal Folds at the Cardia. The pre- phagus and stomach. 'Kronecker and 'Meltzer sence of a mucosal rosette at the cardia has (1883) are accredited with the first scientific been put forward as a mechanicall factor pre- manomdtric study of the lower oesophagus, but venting ,reflux. On distending the stomach the it was not until improved techniques were folds are ironed out as the cardiac orifice is available Ithat a zone of elevated pressure was opened. i(Nauta, 1956). Barrett (1954), Creamer, detected at the gastroesophageal junction ('1955) and Botha !(1958a) all believe ,that a (Fyke and others, 1956; Botha, AstIey and mucosal rosette plugging the cardiac orifice is Carre, 1957; IAtkinson, Edwards, Honour and maintained tone in the 2, lower left actively by underlying Rowlands, 1957a) (Fig. panel). copyright. muscularis mucosa. Allison (1956) however At rest this zone of elevated pressure is 4 to 5 points out that the mucosal apposition may cm. wide as measured Iby a small 0.5 cm. be secondary to ex;ternal compression of the diameter water-filled balloon '(Code and region by the diaphragm, competence depend- Schlegel, 1958). The Ipressure is greater at the ing not on the mucosal rosette but on the end of expiration t'han 'at the end of inspiration, muscular action which produces it. maximal pressures of 80 and 60 cm. of water (c) Flaccid Intra-abdominal Oesophagus. The bei,ng recorded at, and just -below, the effective existence of a segment of oesophagus lying diaphragmatic 'hiatus respectively '(Fyke and within the abdomen has Ibeen disputed (Allison, others, 1956) (Fig. 2, upper panel). This pres- http://pmj.bmj.com/ 1948). Confusion on the maitter may have been sure barrier between stomach and oesophagus due in part to disagreement on the precise is maintained despite changes in the posture of peritoneal relations of the gastroesophageal the individual. That the diaphragm alone is junction (Barrett, 1958). These latter .however not responsible for the zone of increased pres- do not alter the pressure effects, and it 'is now sure may be shown ,by the fact that phrenic accepted that a portion of tuibular "gullet" parallysis is without effect 'upon it, (Atkinson lies within the abdomen and is subject to a and and that the sphincter Sumerling, 1959) on October 1, 2021 by guest. Protected different pressure atmosphere than the rest of can still be detected in cases of hiatal herniaftion the oesophagus above the diaphragm (Dorn- where t,he gastroesophageal junction is dis- horst and others, 1954). On inspiration the placed above the diaphragm '(Atlinson, pressure within the thoracic cavity faMlls, whereas Edwards, Honour and 'Rowlands, 1957b; Code, that within the abdomen rises. The point at Kelly, Schlegel and Olsen, 1962). which the inspiratory 'pressure changes reverse The response to deglutition of the zone of in direction may be referred to as the effective elevated pressure at the gastroesophageall junc- diaphragmatic hiatus and it coincides with the tion indicates that 'it Ipossesses the physiological site of hold-up on swallowing which can be characteristics of a sphincter. 'Unlike the body demonstrated rad,iologically (Creamer and of the oesophagus whidh responds with a others, 1959). peristaltic wave of contraction, its inritial res- The abdomen behaves as a fluid cavity. In ponse is one of 'relaxation. The pressure falls the head down position the ex,ternal pressure immed,iately deglutition takes place and re- applied to the flaccid intra-abdominall oeso- mains low unitil the Iperistaltic complex reaches phagus at the bottom of the abdominal cavity it from the oesophagus above. The area then Postgrad Med J: first published as 10.1136/pgmj.42.487.301 on 1 May 1966. Downloaded from 304 POSTGRADUATE MEDICAL JOURNAL May, 1966 PHYSIOLOGICAL SPHINCTER RESTING

4'+ ·~150l cm. OPEN - IP+ H10 Presu,e BALLOON + Sphincter Stomoch |30 ods Pneunogrop

PRESSURE DETECTING PROBES DEGLUTITION

OPEN-rTI

OPEN-TIP

BALLOON SPHINCTER

~~~~~Swallow copyright. l~~~~cm. § 5 gconds. Pn|unogroph MANOMETRIC STUDY OF THE GASTROESOPHAGEAL JUNCTION FIG. 2. Low Left Panel. Pressure Prcbes. Detecting http://pmj.bmj.com/ Three small-caliber water-filled polyethylene tubes connected proximal,ly to strain gauges. The open tip of the distal tube is covered wi'th a small latex -balloon 5 mm. in diameter. The arrows indicate Ilateral orifices 'in the other tubes at intervals of 5 cm. A fine wire within an extra 'tube is incorporated into the unit to give it some degree of rigidity. Upper Panel Resting Pressures. Withdrawals of an open tip and balloon tipped tube are shown. The upright arrows at each break in the base-line indicate 0.5 om. oral withdrawals of the detecting units t'hrough the gastroesophageal junctional zone. Respiratory on October 1, 2021 by guest. Protected excursions :are recorded 'by a pneumogra'ph, an upward defledtion corresponding to inspiration. .(+) and (-) 'signs indicate respectively ,positive and negative deflections with inspiration. Note the sharp change in direction of the pressure swings from (+) to (-) with inspiration and t'he distinct rise of 'pressure as the units traverse the sph'incter. Lower Right Panel Pressure changes after 'deglutition. Note the 'peristaltic iseq,uence in the .oesophagus and 'that the pressure in the sphincter declines land remains lowered until the wave of deglutition reaches it; the sphincter then closes with a prolonged contraction. These manometric studies were carried out on a dog. The findings are similar in man. responds with a prolonged contraction ;before A similar sphincteric mechanism to that found returning to normal I(Fyke and others, 1956; in man has also been demonstrated at the Atkinson and others, 1957,b). (Figure 2 lower lower end of the oesophagus in a number of right panel). other animal species. The zone of elevated Postgrad Med J: first published as 10.1136/pgmj.42.487.301 on 1 May 1966. Downloaded from May, 1966 GREENWOOD: Control at the Cardia 305

1.

x

..

·Z~~~~~~ 2.~~~~~~~ 1.~~'"

FIG. 3.-Experimenltal Iprocedures. FIG. 4.--Experimental procedures. 1. Severence of junctional zone from diaphragm. Resection of gastroesophageal junation. 2. Obliteration of cardiac angle. Reflux. 3. Removal of mucosal folds at the cardia. No reflux. pressure however is usually narrower than in rl humans. There is a good deal of experimental evid- ence in favour of a ,physiological sphincteric mechanism at the gastroesophageal junction. Hoag, Kiriluk and Merendino i(1954), Braasch and Ellis ,(1956) and Meiss, Grindlay and Ellis (1958) have all shown that of the preservation FIG. 5.-Experimen,tal procedures. gastroesophageal junction is the most important Isolation of lower oesophagus and junotional factor in t'he prevention of reflux. Severance area as blind pouch from the stomach.

of the junctional zone from the diaphragm, Oesophagitis in main oesophagus (a) copyright. obliteration of the cardiac angle, or removal No oesophagitis in blind pouch (b) of the mucosa at the cardiac orifice on the other hand are all 'without effect upon cardiac It is ,probable tha:t .the normal action and competence. (Figs. 3 a,nd 4). T.he experiments of attachments of -the diaphragm restrain the Ingram, Respess and Mu,ller (1959) con- junctional zone within the abdomen where cerned w,ith isolation of the -lower oesophagus the ,physiological sphincter can act to maximu,m and junctional area as a blind pouch from the advantage. The existence of an i,ntra-a,bdominal stomach support :the concept 'that there is a segment of tubular "gullet" is of importance mechanism -at the lower end of the oesophagus in this respect. Other mechanical 'factors such http://pmj.bmj.com/ which prevenits reflux (Fig. 5). as the oblique angle of entry of oesophagus into stomach and mucosal folds at the cardia Summary may contribute to competence of the junctional An area has been detected at the gastro- zone but their importance is limited. wh,ich esophageal junction exhibits the ,features i should like to thank Miss Dewe, Medical Artist of an lintrinsic physiological sphincter. No to St. Thomas' Hospital and also the Department (has of corresponding morphological sphincter of Clinical Photography St. Thomas' for their on October 1, 2021 by guest. Protected been detected to account for these findings. *help in the preparation of the illustrations. It must therefore 'be postulated that the muscle at the lower end of the oesophagus, which REFERENCES outwardly does not differ from that of the ALLISON, P. R. (1948): Peptic Ulcer of the Oeso- phagus, Thorax, 3, 20. rest of the organ, is invested with special ALLISON, P. R. 1(1951): Reflux Esophagitis, Sliding physiological powers. Alternatively it is pos- , and 'the Anatomy of Repair, Surg. si'ble that ithe sphincteric Iproperties reside Gynec. Obstet., 92, 419. within the muscularis mucosa of the region, ALLISON, P. R. (1956): Function and Dysf,unction of or the Cardia, Bull. Johns. Hopk. Hosp., 99, 182. that the muscle fibres of the loop of Willis ALLISON, P. R. and JOHNSTONE, A. S. (1953): The are of importance. Oesophagus Lined with Gastric , This physiological sphincter has' been Thorax, 8, 87. estaiblished as the principal factor responsible ANDERS, H. E., and BAHRMANN, E. (1932): Uber die Sogenannten, Hiatushernien des Ziverch,fells im for competence at the gastroesophageal junc- Haheren Alter und ihre ,Genese, Z. klin. Med., 122, 'tion. It is now clear that the diaphragm plays 736. only a secondary role in control at 'the cardia. AREY, L. B., and TREMAINE, IM. J. (1933): Muscle Postgrad Med J: first published as 10.1136/pgmj.42.487.301 on 1 May 1966. Downloaded from 306 POSTGRADUATE IMEDICAL JOURNAL May, 1966 Content of Lower Oesophagus of iMan, Ainat. Rec. Physiol. (Ainatom. Abt.), Lpz., 395-402. 56, 3;15. His, W. (1903): Studien an Gehiirteten Leichen iiber ATKINSON, M., IEDWARDS, ID. A. W., HONOUR, A. J., Form und Lagerung des Menschlichen Magens, and iROWLANDS, E. N. (1957a): Comparison of Arch. Anat. Physiol. (Anatom. Abt.), Lpz., 345-367. Cardiac and Pyloric Sphincters, Lancet, ii, 918. HOAG, E. W., KIRILUCK, L. IB., and MERENDINO, K. A. ATKINSON, M., EDWARDS, D. A. W., HONOUR, A. J., (1954): Experiences with Upper Gastrectomy, its and ROWLANDS, E. N. (1957b): The Oesophago- Relationship to Esophagitis with Special Reference gastric Sphincter in iHiatus Hernia, Lancet, ii, 1138. to the Esophago-gastric Junction and the Dia.phragm ATKINSON, M., and SUMERLING, M. D. I li'9): The -a Study in the Dog, Amer. J. Surg., 88, 44. Competence of the Cardia after Cardiomyotomy, HURST, A. F. (1925): Les Sphincters du Canal Ali- Gastroenterologia, (Basel), 92, 123. mentaire et leur Signification Clinique, Arch Mal. ,BARRETT, N. R. (1950): Chronic Peptic Ulcer of the Appalr. dig., 15, 1. Oesophagus and 'Oesophagitis', Brit. J. Surg., 38, INGELFINGER, IF. J. 1(19518): Esophageal Motility, 175. Physiol. Rev., 38, 533. BARRETT, N. R. (1954): Hiatus Hernia-a Review INGRAM, P. R., RESPESS, J. C., and MULLER, W. H. of Some Controversial Points, Brit. J. Surg., 42, JR. 1(1959): The Role of an Intrinsic Sphincter 231. Mechanism in the iPrevention of Reflux Esophagitis, BARRETT, N. R. (1958): The Lower Oesophagus Lined Surg. Gynec. Obstet., 109, 659. by Columnar Epithelium. In ,Modern Trends in JACKSON, C. (1922): The Diaphragmatic Pinchoock in Gastroenterology (2nd series), pp. '1474162, ed. F. So-called "Cardiospasm", Laryngoscope, (St. Louis), Avery 'Jones. London: .Butterworth. 32, 139. BOTHA, G. S. M. (1958a): Mucosal Folds at the JOANNIDES, M. '(1929): Influence of the Diaphragm Cardia as a Component of the Gastro-esophageal on the Esophagus and on the Stomach, Arch. internt. Closing fMedhanism, Brit. J. Surg., 45, 569. Med., 44, 856. BOTHA, IG. 'S. M. (1958b): A Note on the Comparative JOHNSTONE, A. S. (1955): Oesophagitis and Peptic Anatomy of the Cardio-oesophageal Junction, Acta, Ulcer of the Oesophagus, Brit. J. Radiol. N.S., 28, anat. (Basel), 34, 52. 229. BOTHA, G. S. M., ASTLEY, R., and CARRE, I. J. KRONECKER, H. and MELTZER, S. J. (1883): Der ;(1957): A Comnbined Cineradiographic and Mano- Schluck-mechanisms, seine Erregung unde seine metric Study of the Gastro-oesophageal Junction, Hemmung, Arch, Anat. Physiol. (Physiol Abt.), Lpz., Lancet, i, 659. 328-362. BRAASCH, J. IW., and IELLIS, F. H. JR. (1956): The zur Anatomie des Oeso- Gastroesophageal Sphincter Mechanism: An Ex- LAIMER, E. (1883): Beitrag copyright. ,perimental Study, Surgery, 39, 901. phagus, Med. Jb. Wien, 333. CANNON, W. IB. (19111): The Mechanical Factors of LENDRUM, F. C. (1937): Anatomic Features of the IDigestion. New York: Longmans Green. Cardiac 'Orifice of the Stomach, Arch. internz. Med., CODE, C. F., and SCHLEGEL, J. F. (1958): The Pres- 59, 474. sure Profile of the Gastroesophageal Sphincter in LERCHE, W. 1(1950): The Esophagus and in ,Man: An Action, Sprinlgfield, Illinois: Charles C. Thomas. Ilmproved Method of Detection, Proc. MARCHAND, P. g(;1955): The Gastro-oesophageal Mayo Clin., 33, 406. '"Sphincter" and t~he Medhanism of Regurgitation, CODE, C. RF., KELLEY, M. L. JR., SCHLEGEL, J. F., and Brit. J. Surg., 42, 504. OLSEN, A. M. (1962): Detection of 'Hiatal Hernia MEISS, J. H., GRINDLAY, J. H., and ELLIS, F. H. JR.

during Esophageal Motility Tests, Gastroenterology, http://pmj.bmj.com/ 43, 521. (1958): The Gastroesophageal Sphincter Mechanism COLLIS, J. L., SATCHWELL, L. M., and ABRAMS, L. D. 11. Further Experimental Studies in the Dog, J. (1954): Nerve Supply to the Crura of the Dia- thorac. Surg., 36, 156. phragm, Thorax, 9, 22. NAGLER, R., and SPIRO, H. M. (1961): Segmental CREAMER, iB. (1955): Oesophageal Reflux and the Response of the Inferior Esophageal Sphincter to Action of Carminatives, Lancet, i, 590. Elevated Intragastric (Pressure, Gastroetnterology, 40, CREAMER, B., HARRISON, G. K., and PIERCE, J. W. 405. (1959): Further Observations on the Gastro- NAUTA, J. (1955): Een Studie van het Afsluitings- oesophageal ,Junction, Thorax, 14, 132. mechanisme Tussen Sl,okdarm en Maag. Leiden: DICK, R. C. S., and HURST, A. (1942): Chronic H. E. Stenffert Kroese. on October 1, 2021 by guest. Protected Peptic Ulcer of the Oesophagus and its Association NAUTA, J. (1956): The Closing Mechanism between with Congenitally Short Oesophagus and Diaphrag- t'he Oesophagus and Stomach, Gastroenterologia, matic iHernia, Quart. J. Med. n.s., 11, 105. (Basel), 86, 219. DORNHORST, A. C., HARRISON, K., and 'PIERCE, J. W. PALMER, E. D. (1953): Attempt to Localize Normal (1954): Observations on the Normal Oesophagus Esophagogastric J,unction, Radiology, 60, 825. and Cardia, Lancet, i, 695. PETERS, P. M. (1955): Closure Mechanisms at the FISCHER, H. (1909): U.ber Functionelle Anpassung Cardia with Special IReference to the Diaphrag- am Fledermausmagen, Pfliigers Arch. ges. Physiol., matico-oesophageal Elastic Ligament, Thorax, 10, 129, 113. 27. FYKE, F. E. JR., CODE, C. F., and SCHLEGEL, J. F. SMIDDY, F. G., and ATKINSON, M. ,(1960): Mechanisms (1956): The Gastroesophageal Sphincter in Healthy Preventing Gastro-oesophageal Reflux in ;the Dog, H,uman Beings, Gastroenterologia, (Basel), 86, 135. Brit. J. Surg., 47, 680. GAHAGAN. T. (1962): The Function of the Muscula- WILLIS, T. (1674-5): Pharmacutice Rationale: Sive ture of the Esophagus and Stomach in the Eso- 'Diatiba de Medicamentorum Operationibus in phagogastric Sphincter Medhanism, Surg. Gynec. Humano Corpore. Oxford (ed. in English 1679). Obstet., 114, 293. WOLF, B. S. (1960): The Esophagogastric Closing GUBAROFF, A. VON (1886): Ueber Iden Verschluss des Mechanism: Role of the Abdominal Esophagus, J. Menschlichen tMagens an der Cardia, Arch. Anat. Mt. Sinai Hosp., 27, 404.