Stapes

“ The branchial sac enlarges, its walls become penetrated by blood-channels, and grow out to form bars and papillae, and the number of openings greatly increases by the primary gill-slits being broken up into the transverse rows of stigmata. The stomach and intestine, which developed as an outgrowth from the back of the branchial sac at the right side, become longer and curve, so that the end of the intestine acquires an opening into at first the left hand side, and eventually the cloacal or median part of the atrial cavity. ”

“ A demand for a crucial examination of the skull, the heart, lungs, of the chest, the stomach, liver and other organs of the abdomen is made. The septum of the brain, the pericardium of the chest—the diaphragm of the abdomen which is a dividing septum between the abdomen and chest. In this examination we must know the reasons why any organs, vessel or any other substance is located at a given place. We must run with all the rivers of blood that travel through the system. ”

“ The Liver.—Below the diaphragm on the right and extending across above the stomach, resting in a way upon the transverse colon and the small intestine, is the liver, the largest gland in the body. It is dark reddish-brown in color and is larger in proportion in the child than in the adult. The upper surface is convex and lies in contact with the diaphragm, while the lower surface is concave to fit over the organs beneath. With a full breath it comes downward and forward, with the edge against the abdominal wall, and can be easily felt. ”

“ The future greater curvature is directed dorsad and a little to the left toward the vertebral column, while the concave lesser curvature is turned ventrad and a little to the right toward the ventral abdominal wall. At this time there is but little indication of the subsequent extension of the organ to the left of the œsophageal entrance to form the great cul-de-sac or fundus of the adult stomach. ”

“ The oesophagus leaves the branchial sac in the dorsal middle line, near the posterior end of the dorsal lamina. It is a short curved tube which leads ventrally to the large fusiform thick-walled stomach, ridged internally. The intestine emerges from the ventral end of the stomach and soon turns anteriorly, then dorsally, and then posteriorly, so as to form a curve, the intestinal loop, in which the ovary lies, open posteriorly. ”

“ It is the Receptacle of the Aliments or Food convey'd thither thro' the Oesophagus or Gullet, which is a Canal, or kind of streight Gut that reacheth from the Throat to the Mouth of the Stomach. The Stomach it self is situated immediately under the Diaphragm or Midriff, between the Liver and the Spleen, having two Orifices, whereof the Left is properly call'd Stomachus, or the Upper, and the Right (at its other Extremity) Pylorus, or the lower Orifice. Its Figure resembleth that of a Bag-Pipe, and the greater part of its Body lies toward the Left side. ”

“ After opening the abdominal cavity of the human adult, elevating the liver and depressing the stomach, the hepatic attachment of the lesser omentum can be traced as already described. It will then be observed that the gastric attachment of the membrane lies in one plane following the lesser curvature while the hepatic attachment forms a broken line, with the angle situated at the left extremity of the transverse fissure. ”

“ Perhaps the gelatinous knob you detached was not an Eolis, If your knife reaches a stomach which is not arborescent, you may have a Doris. The dorsal papillæ of Doris are genuine lungs, but they breathe for only part of the body. They aerate only the blood which goes to the liver, an organ which appears now, not as a row of bile-cells, but as a well-defined gland. The foot shares the labor of the lungs, they breathing for the liver, it for the rest of the body. ”

“ If we pursue our researches into the interior of this animal, we find within the framework of the skeleton a great cavity, or rather, I should say, two great cavities,–one cavity beginning in the skull and running through the neck-bone, along the spine, and ending in the tail, containing the brain and the spinal marrow, which are extremely important organs. The second great cavity, commencing with the mouth, contains the gullet, the stomach, the long intestine, and all the rest of those internal apparatus which are essential for digestion ”

“ The seat of pain is often at a great distance from that of the affected organ. In disease of the liver, the pain is generally felt at the top of the right shoulder. The right phrenic nerve sends a branch to the liver: the third cervical nerve, from which the phrenic arises, distributes numerous branches to the neighborhood of the shoulder: thus is established a nervous communication between the shoulder and the liver. ”

“ Hence the apertures of the two hepatic ducts are seen, one on each side, in this part of the alimentary canal when it is laid open from above. Every cæcum of the liver has a thin outer wall, lined internally by a layer of cells, constituting what is termed an epithelium; and, at the openings of the hepatic ducts, this epithelium passes into a layer of somewhat similar structure, which lines the mid-gut, and is continued through the rest of the alimentary canal, beneath the cuticula. Hence the liver may be regarded as a much divided side pouch of the mid-gut. ”

“ This membrane forms in adult man by its transverse attachment to the abdominal background the cephalic limit of the larger lower compartment of the abdomen, which is framed laterally by ascending and descending colon, continuous below with the pelvic cavity and occupied chiefly by the freely movable coils of the jejuno-ileum. ”

“ The skin is not, as it should be, held fast by the connective tissue, but lies loose over the cavity; and a similar pathological condition exists under the mucous membrane of the anus, rectum, and sigmoid flexure, which circum­stance might lead one, in some instances, to conclude that there was almost an entire separation of the mucous membrane from the areolar tissue, by the ridges, folds, large, pouched, prolapsed, sacculated regions of mucous membrane that has the appearance of having been simply carelessly laid over the muscular structure of the organs. ”

“ We speak of the liver as growing into and between the layers of the ventral mesogastrium, because this conception offers the opportunity of more clearly explaining the adult condition. Actually, however, the membrane develops, as a new structure, after the first differentiation of liver and stomach, as these organs descend into the abdominal cavity. ”

“ To cut through the abdominal fascia, carefully puncture it above the stomach, so the opening will be large enough to admit the forefinger of the right hand being introduced through the opening; then holding the scalpel with its edge upwards, the back resting along the extended forefinger, introduce both into opening, and cut from downward upwards into the fascia of the abdomen in a straight line across from the stomach to the liver in a similar way to that above described for cutting through the skin. ”

“ A review of the visceral contents of the abdomen shows that we have to deal chiefly with the divisions of the alimentary tract below the œsophagus and the structures directly derived from the same, as liver and pancreas, or associated topographically with the alimentary canal, as the spleen. ”

“ The anterior wall may be cut midway between the greater and lesser curvatures, or the cut may follow the greater curvature, extending through the cardia into the œsophagus. As the stomach is opened its contents are inspected and removed. They should not be allowed to escape into the abdominal cavity. When the organs are removed en masse the stomach may be opened from the cardiac end. The organ may also be opened by an incision through its posterior wall or along its lesser curvature, as occasion may demand. ”

“ He had noted that the abdominal cavity was lined with a peculiar saclike membrane, the peritoneum, which also surrounded most of the organs contained in the cavity, and he made special note that this membrane also enveloped the liver in a peculiar manner. The exactness of the last observation seems the more wonderful when we reflect that even to-day the medical, student finds a correct understanding of the position of the folds of the peritoneum one of the most difficult subjects in anatomy. ”

“ On the dorsal side of the gut the [Pg 626] two halves of the body cavity never coalesce, but eventually the splanchnic layers of epithelium of the two sides, together with a thin layer of interposed mesoblast, form a delicate membrane, known as the mesentery, which suspends the gut from the dorsal wall of the body (figs. 119 and 351) . On the dorsal side the epithelium lining of the body cavity is usually more columnar than elsewhere (fig. 351) , and its cells partly form a covering for the generative organs, and partly give rise to the primitive germinal cells. ”

“ Thus in the adult human subject the structures bounding the foramen at the margin of the entrance into the narrow channel would be above caudate lobe of liver, behind postcava, below duodenum adherent to ventral surface of right kidney, in front first portion of duodenum and lesser omentum. ”

“ This passes back into a-curious conical sac which is commonly termed the stomach, but which has more the character of a crop. Coming off from the under side of the sac and communicating with it by a narrow opening, there is an elogated tubular organ, the walls of which are so thick and muscular that it might almost be compared to a gizzard. It is directed forward, and opens by a narrow prominent aperture into the intestine, which runs straight back to the vent. ”

“ The pancreas is examined by turning the stomach toward the thoracic cavity, cutting or tearing the gastrocolic omentum, and cutting the exposed organ by a longitudinal incision through head, body and tail, or by means of parallel transverse incisions made through the different parts of the organ. ”

“ The descriptions and illustrations of the stomach in anatomical works must be disregarded as cadaveric. In the living body, the empty stomach is usually found, on endoscopic inspection, to be a collapsed tube of such shape as to fit whatever space is available at the particular moment, with folds and rugae running in all directions, the impression given as to form being strikingly like searching among a mass of earth worms or boiled spaghetti. ”

“ But even in these rudimentary forms the point where the liver develops from the entodermal intestinal tube marks the separation of fore- and midgut. The stomach, when it develops, is situated cephalad of the entrance of the hepatic duct into the intestine. The section cephalad of the duct opening may be very short, and the food digested further on in the intestinal tube. Consequently a function which in these lower vertebrates is assigned to the midgut becomes transferred in the higher forms to a specialized segment of the foregut, situated cephalad of the hepato-enteric duct. ”

“ Now cut oesophagus just in front of stomach, and cut the rectum, cut through the mesentery supporting the intestine, and remove and unravel alimentary canal; cut open, wash out, and examine caecum and stomach. Bleeding to a considerable extent is inevitable, chiefly from the portal vein. The liver had better remain if the same rabbit is to serve for the second dissection. ”

“ The two lateral lobes are gradually more and more constricted off from the central one, and become eventually quite separated from it; their cavities remain independent, and form in the adult the body-cavity, divided by a mesentery into two distinct lateral sections. The inner layer of each of the two lateral lobes forms the mesoblast of the splanchnopleure, the outer layer the mesoblast of the somatopleure. The central division of the primitive gastræa cavity remains as the alimentary tract of the adult. ”

“ When they quit the society, and act singly, their parts may be more readily distinguished, and will be found to consist of a head, abdomen, and tail. The head is often drawn back so far into the abdomen, that it cannot be seen, exhibiting only a projecting, broad kidney-shaped disc. The abdomen, Fig. 51, d, is oblong, oval, and pellucid, replete with obscure intestines, amongst which are one or two remarkable black [558] oval spots, e; the tail, f, is sharp, twice as long as the abdomen, either rough and annulated, or altogether smooth. ”

“ The suspensory ligament of the liver is continued posteriorly along the midline of the ventral body wall; the dorsal edge supports a funnel which opens into the abdominal cavity by a long, narrow mouth. From the anterior end of the funnel two narrow tubes pass to the right and left over the anterior surface of the liver. They end blindly in the tissues dorsal to the anterior end of the liver. ”

“ The assumption of peritoneal adhesion, and consequent obliteration of serous areas, offers many advantages in considering the adult human abdominal cavity, especially from the standpoint of comparative anatomy. ”

“ The hepatic portal vein is formed by the veins of the œsophagus, stomach, and intestines. After traversing the capillary vessels of the liver, the revehent hepatic veins unite to form an extensive hepatic sinus before entering the heart. ”