« PrécédentContinuer »
apex of the heart. The greater curvature crosses behind the left costal margin opposite the tip of the ninth costal cartilage, that is to say, where the transpyloric line intersects the left lateral line. The lowest part of the great curvature, situated generally in the median plane, extends down to, or a little above, the infracostal plane, about two inches above the umbilicus. The lesser curvature and the adjacent part of the anterior wall of the stomach are overlapped by the anterior margin of the liver.
Radiography of Stomach.-Radiograms of the stomach, taken after a “bismuth meal," show that the form and position of the stomach in the living subject differ considerably from that which it presents in the cadaver.
In the cadaver, owing to loss of muscular tone, it presents itself as a more or less empty pear-shaped bag with collapsed and flaccid walls. The same applies to a large extent to the stomach as seen in the operating room, its normal tonicity being almost entirely held in abeyance by the anaesthetic.
In the living subject, the form and position of the stomach are found to vary not only according to the amount of food it contains, but also according to whether the patient occupies the erect or the recumbent posture. The most reliable as well as the most useful, information regarding the form, the position, and the motor activity of the stomach is obtained by "screen" examinations and radiograms taken with the patient in the erect posture. When examined in this way, after partly filling the stomach with a "bismuth meal," the organ is seen to possess a distinctly J-shaped form. The stem of the J, which is represented by the body of the stomach, lies immediately and entirely to the left of the vertebral column. The fundus, which is slightly more expanded than the body, reaches up to the left cupola of the diaphragm; it is represented in the skiagram as a light semilunar shadow, the horizontal inferior margin of which corresponds to the superior limit of the bismuth. This clear semilunar area is due to the rising up of the gaseous contents of the stomach to the highest part of the cavity. The cardiac orifice is seen to lie opposite the left side of the fibro-cartilage between the tenth and eleventh thoracic vertebræ. The shadow of the curved pyloric portion of the stomach, after crossing the left side of the vertebral column opposite the third and fourth lumbar vertebræ, ascends as the pyloric canal to join the duodenum at or a little to the right of the median plane, opposite the second (not infrequently the third) lumbar vertebra. The pylorus itself is represented by a light disc due to a break in the continuity of the bismuth, caused by contraction of the pyloric sphincter. The lowest portion of the greater curvature, which generally lies at or a little to the left of the median plane, reaches, in the erect posture, down to the level of the middle or inferior border of the fourth lumbar vertebra, or, in other words, to the umbilicus and the highest part of the iliac crest.
As more food enters the stomach its capacity is increased by lateral expansion rather than by any elevation of its fundus or downward expansion of its greater curvature. The normal tonic action of the gastric muscle is able to hold up the meal against the action of gravity to the level of the cardiac orifice.
When, as not infrequently happens, the normal muscular tonicity of the stomach is lost, the bismuth meal is no longer held up against the action of gravity, but at once sinks to the most dependent part of the stomach where it lies as in a flaccid sac, and gives rise to a crescentic shadow which may reach down almost, or even quite, to the level of the pubes.
In gastroptosis, and in general visceroptosis, the whole stomach may be displaced downwards without any great loss of its tonicity.
During a "screen" examination after a bismuth meal, the peristaltic movements of the stomach can be seen to pass in distinct wave-like indentations from left to right along the greater curvature, and to increase in force as they approach the pylorus.
When the stomach is hypertrophied and dilated, as a result of pyloric obstruction, the peristaltic waves are more pronounced, and the bismuth shadow extends well over to the right of the median plane, owing to the dilated pyloric antrum and pyloric canal being carried over to the right, in front of the superior part of the duodenum. The stomach tends, therefore, to lose its somewhat J-shaped
tubular form, and the axis of its body becomes more oblique. In the infant and young child the stomach is flask-shaped rather than J-shaped, and its axis is less vertical than in the adult. The elongated form of the adult stomach is acquired as a result of the erect posture.
It must be remembered that the only really fixed part of the stomach is the region of the cardia, so that the form and position of the organ may be considerably influenced by the condition of the neighbouring organs. For example, it may be displaced downwards and to the left by enlargement of the liver, upwards by distension of the intestines, and to the right by distension of the left colic flexure.
Overlying the stomach is an important surface area known to clinicians as the semilunar space of Traube. This space, which yields a deeply tympanitic note on percussion, is bounded, above, by the inferior margin of the left lung; below, by the left costal margin; to the right, by the anterior margin of the left lobe of the liver; behind and to the left, by the anterior border and anterior basal angle of the spleen. The line of the costo-diaphragmatic pleural reflection crosses the space about midway between its superior and inferior limits. The tympanitic area of the space is diminished superiorly by pleuritic effusion, towards the right by enlargement of the liver, and towards the left by enlargement of the spleen.
Perforation of an ulcer on the anterior wall of the stomach leads to extravasation into the greater sac of the peritoneum, while if the perforated ulcer is on the posterior wall, extravasation takes place into the omental bursa. The close relation of the splenic artery and its branches to the posterior wall of the stomach explains the severe hæmorrhage which is sometimes caused by a posterior gastric ulcer. The surgeon may reach the posterior wall of the stomach through the gastro-colic ligament, or, after throwing upwards the greater omentum and transverse colon, by traversing the transverse mesocolon; by the former route the posterior wall of the stomach is reached through the anterior wall of the omental bursa, in the latter through its posterior wall.
When a partial resection of the stomach, for malignant disease, is performed, the bleeding is controlled by ligaturing the main vessels at an early stage of the operation. These are the right and left gastrics at the lesser curvature, the gastroduodenal behind the first part of the duodenum, and the right and left gastroepiploics at the greater curvature. The left gastric should be ligatured as near the cardia as possible, so that the whole chain of lymph glands along the lesser curvature may be removed. Care is taken to remove also all the glands which lie behind the first part of the duodenum in relation to the gastro-duodenal artery and head of the pancreas, as well as those along the right half of the greater curvature in relation to the right gastro-epiploic artery. If the disease has spread to the retro-peritoneal lymph glands, surrounding the coeliac artery, above the pancreas, the chances of a permanent recovery are very remote.
In the classical "no-loop" gastro-enterostomy operation a longitudinal opening in the commencement of the jejunum is anastomosed by suturing it to an opening in the posterior wall of the stomach, near the greater curvature. The jejunum is applied to the stomach in such a way that it maintains its normal direction, namely, obliquely upwards and to the left. To bring the surfaces of the two organs in contact, surgeons are in the habit of protruding the posterior wall of the stomach through an opening made in the transverse mesocolon, on the proximal side of the arch formed by the middle and left colic arteries. A better plan, however, is to make an opening also into the omental bursa through the gastro-colic ligament & little below the gastro-epiploic vessels, and then to bring the jejunum into contact with the posterior wall of the stomach by pushing it (the jejunum) upwards through the opening in the transverse mesocolon. By this plan the posterior wali of the stomach along with the jejunum can be protruded through an opening in the gastro-colic ligament, and can be more easily delivered out of the abdominal cavity.
When the posterior wall of the stomach and transverse colon are held down by adhesions, a long loop of jejunum is brought up in front of the greater omentum and transverse colon and anastomosed to the anterior wall of the stomach.
The Duodenum. The duodenum is the widest, thickest, and most fixed part
of the small intestine. For descriptive purposes it is divided by anatomists into three parts. From the surgical standpoint it may with advantage be subdivided into a supra-colic and an infra-colic portion, the former, comprising the superior and the upper half of the descending part, being situated above the attachment of the transverse mesocolon; while the latter, comprising the lower half of the descending part along with both subdivisions of the third part, being situated below this attachment. To expose the supra-colic portion the greater omentum and the transverse colon must be pulled downwards, while to expose the infra-colic portion they are thrown upwards along with the transverse mesocolon.
The first portion proper (pars superior) lies in the right part of the epigastric region, medial to the gall-bladder, where it is overlapped by the quadrate lobe of the liver. As regards its blood-supply, it occupies the frontier zone between the coeliac and superior mesenteric vascular areas, and the vessels which supply it vary considerably in their size and mode of origin.
This peculiarity of its blood-supply may partly account for the relative frequency with which this portion of the intestine is found to be the seat of ulceration. The first inch or so the duodenum possesses some degree of mobility, being surrounded by the same two layers of peritoneum which invest the stomach. Beyond this it is in direct contact posteriorly and inferiorly with the pancreas, while descending behind it are the common bile-duct and the gastro-duodenal artery. The relations must be borne in mind in performing the operation of pylorectomy. When an ulcer of the superior part perforates, extravasation takes place, in the first instance, into the supra-colic compartment of the peritoneum, thence into its hepato-renal pouch, and subsequently down along the ascending colon into the right iliac fossa, hence the possibility of mistaking the condition for an acute appendicitis. Perforation of the ulcer, however, is often prevented by the duodenum becoming adherent especially to the gall-bladder, to the omentum, or to the transverse colon.
If the finger is passed upwards, backwards, and to the left, immediately above the first part of the duodenum and behind the right free border of the lesser omentum, it will pass through the foramen epiploicum into the omental bursa of the peritoneum.
The second portion of the duodenum (pars descendens) descends in the epigastric and umbilical regions a little medial to the right lateral plane. The attachment of the transverse mesocolon crosses it about its middle, while posteriorly it lies in front of the hilum and medial border of the right kidney, from which it is separated by loose areolar tissue. The procedure necessary to mobilise this portion of the duodenum has been referred to already.
The horizontal portion of the inferior part of the duodenum occupies the superior part of the umbilical region, and crosses the median plane about one inch above a line joining the highest part of the iliac crests; behind its commencement is the superior part of the right ureter.
The ascending portion of the inferior part of the duodenum crosses the infracostal plane, and ascends upon the left side of the vertebral column opposite the second and third lumbar vertebra.
The duodeno-jejunal flexure, which lies in the transpyloric plane one inch to the left of the median plane, is the landmark which the surgeon makes for when he wishes to identify the commencement of the jejunum (Fig. 946, p. 1204). To find the flexure the greater omentum and transverse colon should be thrown upwards and the finger passed along the inferior layer of the transverse mesocolon to the left side of the vertebral column. The flexure lies in the angle or recess formed by the left side of the second lumbar vertebra and the inferior surface of the body of the pancreas. With the finger in this recess the commencement of the jejunum may be hooked forward a little to the left of the superior mesenteric vessels at the root of the mesentery. In connexion with the duodeno-jejunal junction is the inferior duodenal fossa of Jonnesco, formed by a fold of peritoneum which stretches from the left side of the fourth or ascending part of the duodenum upwards to become attached to the peritoneum of the posterior abdominal wall close to the medial border of the left kidney. The free edge of the fold and the mouth of the
fossa look upwards. This is one of the situations at which an internal hernia sometimes develops, the sac, as it enlarges, extending further and further into the extra-peritoneal tissue on the posterior abdominal wall. Should strangulation occur, the inferior edge of the orifice must be divided in a downward direction, in order to avoid the inferior mesenteric vein which curves round the anterior and superior aspects of the orifice (Treves).
Jejunum and Ileum.-To expose the coils of the jejunum and ileum completely, the greater omentum, along with the transverse colon and the greater curvature of the stomach, must be turned upwards. On account of the oblique attachment of the mesentery, the greater number of the coils lie in the left infra-colic peritoneal compartment, where they extend upwards to the left of the vertebral column as far as the attachment of the transverse mesocolon and the inferior surface of the pancreas; here they lie in front of the inferior pole of the left kidney, in the angle of the left colic flexure.
The only certain means which the surgeon has of distinguishing the superior from the inferior coils of small intestine is by their relation to the duodenojejunal flexure and the ileo-cæcal junction. Occasionally the plicæ circulares
FIG. 1104.-THE CECAL FOLDS AND FOSSE,
In A, the cæcum is viewed from the front; the mesentery of the vermiform process is distinct, and is attached above to the inferior surface of the portion of the mesentery going to the end of the ileum. In B, the cæcum is turned upwards to show a retro-cæcal fossa, which lies behind it, and the beginning of the ascending colon (from Birmingham).
and the aggregated lymph nodules can be seen from the peritoneal aspect and the jejunum and ileum thereby respectively identified. The terminal portion of the ileum, which is attached by the inferior end of the mesentery to the superior part of the right wall of the pelvis major, crosses the superior aperture of the pelvis minor, and ascends along the medial edge of the cæcum before opening into it. The terminal loop of the ileum may be hooked up by passing the finger along the medial side of the cæcum downwards over the medial border of the psoas major and the external iliac vessels into the pelvis minor.
Meckel's diverticulum, which is due to persistent patency of the proximal portion of the vitelline duct, is situated usually from two to three feet above the valve of the colon; its average length is two inches. Springing from the anti-mesenteric border of the ileum, its termination is usually free, but it may be adherent either to the anterior abdominal wall, to the mesentery, or, more rarely, to one of the adjacent viscera. When its termination is fixed it may give rise to strangulation of the intestine.
Cæcum. The cæcum occupies the right iliac region and extends from the anterior superior spine of the ilium to the superior aperture of the pelvis minor. When empty, it is generally more or less completely overlapped by small intestine, and frequently also by the greater omentum. When partly distended, the cæcum comes
a result of
the pelvis m
ssue behi reach even When, in descent, th inferior pol become ad
to the ute
in contact with the anterior abdominal wall immediately above the lateral half of the inguinal ligament. In the normal condition it is completely surrounded by peritoneum, and can, therefore, along with the vermiform process, be readily delivered out of the abdomen. In chronic constipation, associated with intestinal atony, the cæcum is thin-walled, dilated, abnormally movable, and often prolapses into the pelvis.
The position of the ileo-cæcal valve corresponds, on the surface of the body, to the medial angle between the intertubercular and right lateral lines, while the orifice of the vermiform process is one inch lower. It is to be noted that the lower end of the ileum protrudes somewhat into the cæcum, and that its circular muscular' fibres are prolonged into the flaps of the colic valve. Both of these anatomical arrangements favour the occurrence of intussusception. In infants, other predisposing causes are: (1) the relatively rapid enlargement of the lumen of the large intestine as compared with the small; (2) the greater mobility of the cæcum; and (3) the frequent presence of a mesentery to the ascending colon.
Vermiform Process. The vermiform process (O.T. vermiform appendix), which springs from the postero-medial aspect of the cæcum, one inch below the ileo-cæcal junction, is provided with a well-developed "meso-enteriole" derived from the posterior aspect of the lowest part of the ileac mesentery. It is this portion of the posterior layer of the mesentery which sometimes develops a band-like thickening, which, by dragging upon the inferior end of the ileum, produces the kink to which attention has been directed by Arbuthnot Lane. The artery of the vermiform process is the only vessel which supplies the process; it occupies the free border of the meso-enteriole and gives off several branches which pass between its two layers to reach the organ. In amputating the vermiform process the artery is ligatured on the proximal side of its first branch in order to control the bloodsupply to the stump of the process. The fact that the vermiform process is supplied by a single artery predisposes it to gangrene should the vessel become thrombosed, or should the circulation in it be interfered with by kinking as a result of adhesions.
The vermiform process will generally be found to pass either upwards and medially, behind the lower end of the ileum, or downwards and medially, so as to overhang the external iliac vessels at the superior aperture of the pelvis minor; less frequently it ascends in the pouch behind the commencement of the ascending colon. ARTERY OF THE When, as not infrequently happens, the retro-cæcal fossa is prolonged upwards to form a pouch behind the colon, the vermiform process almost invariably ascends into it, and should it be diseased, it may give rise to a The illustration gives a view of the cæcum from behind. retro-cæcal abscess. The abscess may perforate the posterior wall of the cæcum, or it may ulcerate through the posterior peritoneum; in the latter case the suppuration may spread upwards, in the loose fatty sub-peritoneal tissue behind the colon, into the lumbar and perinephric regions; and it may reach even the under surface of the diaphragm and form a subphrenic abscess. When, in the course of its development, the cæcum has failed to complete its descent, the vermiform process may lie in the lumbar region in relation to the inferior pole of the kidney. When it dips downwards into the pelvis minor it may become adherent to the pelvic colon, the rectum, or the bladder, and in the female to the uterine tube or the ovary. To find the vermiform process, the best plan
FIG. 1105. THE BLOOD-SUPPLY OF THE CÆCUM AND VER-
The artery of the vermiform process, and the three
tænia coli springing from the base of the process, should be specially noted. (Modified by Birmingham from Jonnesco.)
POSTR CAECAL A.