name of tartar or tartar of the teeth. Different views have existed in regard to its origin. Some have supposed it to be a secretion, others a deposition from the saliva, which is the most probable opinion; and others that it is an exhalation from the capillary vessels, to which the mucous membrane of diseased gums is liable. It has been affirmed by M. Mandl,' to be a collection of calcareous skeletons of infusoria, agglutinated by means of dried mucus. 4. The Pancreatic Secretion. The pancreas or sweetbread, (Fig. 332, h, t, i,) mour called succus pancreaticus, pancreatic juice. Fig. 332. In this figure, which is altered from Tiedemann, the Liver and Stomach are turned up to show the Duodenum, the Pancreas, and the Spleen. 1. The under surface of the liver. g. Gall-bladder. f. The common secretes a juice or huIts texture resembles that of the salivary glands; and hence it has been called by some the abdominal salivary gland. It is situate transversely in the abdomen; behind the stomach; towards the concavity of the duodenum; is about six inches in length, and between three and four ounces in weight. From the results of six examinations, Dr. Gross gives the following as its mean weight and dimensions: bile-duct, formed by the union of a duct from the gall-bladder, called Weight 2 ounces; the cystic duct, and of the hepatic duct coming from the liver. 0. The cardiac end of the stomach, where the esophagus enters. s. Under length, 7 inches; surface of the stomach. p. Pyloric end of stomach. d. Duode num. h. Head of pancreas; t, tail; and i, body of that gland. The breadth at the body substance of the pancreas is removed in front, to show the pancreatic and splenic extreduct (e) and its branches. 7. The spleen. v. The hilus, at which the blood vessels enter. c. Crura of diaphragm. n. Superior mesenteric mity, 16 lines; breadth at the neck, artery. a. Aorta. 12 lines; at the head, 2 inches and 3 lines; thickness at the body, neck, and splenic extremity, 4 lines; thickness at the head, 8 lines. M. Bécourt found the average length of thirty-two to be 8 inches; and the weight between three and four ounces. It is of a reddish-white colour, and firm consistence. Its excretory ducts terminate in one,called duct of Wirsung,-which opens into the duodenum, at times separately from the ductus communis choledochus, but close to it; at others, confounded with, or opening into, it." The amount of fluid secreted by the pancreas does not seem to be 1 Gazette des Hôpitaux, 8 Août, 1843, p. 363. 2 Elements of Pathological Anatomy, ii. 357, Boston, 1839. 3 Recherches sur le Pancréas, ses Fonctions et ses Altérations Organiques, Thèse, Strasbourg, 1830, cited by Mondière, Archives Générales de Médecine, Mai, 1836. • Magendie, Précis Elémentaire, i. 462; and J. P. Mondière, op. cit. considerable. M. Magendie, in his experiments, was struck with the small quantity discharged. Frequently, scarcely a drop issued in half an hour; and, occasionally, a much longer time elapsed. Nor did he find that the flow, according to common opinion, and to probability, was more rapid whilst digestion was going on. It will be readily understood, therefore, that it cannot be an easy task to collect it. De Graaf1 affirms, that he succeeded, by introducing into the intestinal end of the excretory duct, a small quill, terminating in a phial fixed under the belly of the animal. M. Magendie2 states, that he tried this plan several times, but without success; and he believes it to be impracticable. The plan he adopts is to expose the intestinal orifice of the duct; to wipe the surrounding mucous membrane with a fine cloth, and as soon as a drop of the fluid oozes to suck it up by means of a pipette or small glass tube. In this way, he collected a few drops, but never sufficient to undertake a satisfactory analysis. Messrs. Tiedemann and Gmelin3 make an incision into the abdomen; draw out the duodenum, and a part of the pancreas; and, opening the excretory duct, insert a tube into it; and a similar plan was adopted successfully on a horse by MM. Leuret and Lassaigne. The difficulty experienced in collecting any quantity is a probable cause of some of the discrepancy amongst observers, regarding its sensible and chemical properties. Certain of the older physiologists affirm that it is acidulous and saline; others, that it is alkaline. The majority of those of the present day compare it with saliva, and affirm it to be inodorous, insipid, viscid, limpid, and of a bluish-white colour. The latest experimenters by no means accord with each other. According to M. Magendie, it is of a slightly yellowish hue, saline taste, devoid of smell, occasionally alkaline, and partly coagulable by heat. MM. Leuret and Lassaigne found that of the horse-of which they obtained three ounces,-to be alkaline, and composed of 991 parts of water in 1000; an animal matter, soluble in alcohol; another, soluble in water; traces of albumen and mucus; free soda; chloride of sodium; chloride of potassium, and phosphate of lime. In their view, consequently, the pancreatic juice strongly resembles saliva. Messrs. Tiedemann and Gmelin succeeded in obtaining upwards of two drachms of the juice in four hours; and, in 100 parts, found from five to eight of solid parts. These consisted of osmazome; a matter which became red by chlorine; another analogous to casein, and probably associated with salivary matter; much albumen; a little free acid, probably acetic; acetate, phosphate, and sulphate of soda, with a little potassa; chloride of potassium, and carbonate and phosphate of lime-so that, according to these gentlemen, the pancreatic juice differs from saliva in containing—a little free acid, whilst saliva is alkaline; much albumen, and matter resembling casein; but little mucus and salivary matter, and no sulpho-cyanate of potassa. In an examination, by M. Blondlot," of three or four grammes of fluid, obtained from the duct of a large dog, he found no evidences of albumen, when 1 Tract. de Pancreat., Lugd. Bat., 1761; and Haller, Elem. Physiol., lib. xxii. sect. 8, Bern., 5 Haller, op. cit.; and Seiler, art. Pancreas, Pierer's Anat. vi. 100, Altenb., 1825. • Trané Analytique de la Digestion, p. 124, Paris, 1844. 4 Recherches, &c., p. 49. Physiol. Real Wörterb., Band he passed an electric current through it. He, also, holds it to be of the same nature as saliva. The precise use of the pancreatic juice in digestion-as we have previously seen-is not determined. Brunner' removed almost the whole pancreas from dogs, and tied and cut away portions of the duct; yet they lived apparently as well as ever. The secretion, therefore, cannot be indispensable. Its main uses seem to be to favour the absorption of oleaginous matters.2 5. The Biliary Secretion. The biliary secretion is, also, a digestive fluid, and has been treated of in the appropriate place. The mode, however, in which the process is effected, has not yet been investigated. The apparatus consists of the liver, which accomplishes the formation of the fluid; the hepatic duct-the excretory channel, by which the bile is discharged; the gallbladder, in which a portion of the bile is retained for a time; the cystic duct-the excretory channel of the gall-bladder; and the ductus communis choledochus or choledoch duct, formed by the union of the hepatic and cystic ducts, which conveys the bile immediately into the duodenum. The liver (Fig. 333) is the largest gland in the body; situate in the abdomen beneath the diaphragm, above the stomach, the arch of the colon, and the duodenum; filling the whole of the right hypochondrium, and more or less of the epigastrium, and fixed in its situation by duplicatures of the peritoneum, called ligaments of the liver. The weight of the human organ is generally, in the adult, about three or four pounds. Some make the average about five pounds; but this is a large estimate. Of 60 male Experimenta nova circa Pancreas, Amstel., 1683; and J. T. Mondière, op. cit. 2 Vol. i. p. 614. Lond. and Edinb. Monthly Journ. of Med. Sciences, April, 1843, p. 323. kidney. On the latter surface, two fissures are observable, the one passing from before to behind, and lodging the umbilical vein in the fœtus-called horizontal sulcus or fissure, great fissure or fossa umbilicalis; the other cutting the last at right angles, and running from right to left, by which different nerves and vessels proceed to and from the liver, and called principal fissure, or sulcus transversus. The liver itself is composed of the following anatomical elements: 1. The hepatic artery, a branch of the coeliac which ramifies minutely through the substance of the organ. The minuter branches of this vessel are arranged somewhat like the hairs in a painter's brush, and have hence been called penicilli of the liver. Mr. Kiernan1 believes, that the blood, which enters the liver by the hepatic artery, fulfils three functions:-it nourishes the organ; supplies the excretory ducts with mucus; and, having fulfilled these objects, becomes venous; enters the branches of the portal veins, and not the radicles of the hepatic, as usually supposed, and contributes to the secretion of bile. 2. The vena porta, which, we have elsewhere seen, is the common trunk of the veins of the digestive organs and spleen. It divides like an artery, its branches accompanying those of the hepatic artery. Where it lies in the transverse fissure, it is of great size, and has hence been called sinus venæ porta. The possession of two vascular systems, containing blood, is peculiar, perhaps, to the liver, and has been the cause of difference of opinion, with regard to the precise fluid-arterial or venous-from which the 27 bile is derived. According to Mr. Kiernan, the portal vein fulfils two functions: it carries the blood from the hepatic ar 26 4 32 Fig. 334. tery, and the mixed blood to Inferior or Concave Surface of Liver, showing its Subdivisions into Lobes. the coats of the excretory ducts. It has been called vena arte- 1. Centre of right lobe. 2. Centre of left lobe. 3. Its anterior, inferior or thin margin. 4. Its posterior, thick riosa, because it ramifies like or diaphragmatic portion. 5. Right extremity. 6. Left extremity. 7. Notch on the anterior margin. 8. Umbian artery, and conveys blood lical or longitudinal fissure. 9. Round ligament or refor secretion: but, as Mr. Kier- mains of umbilical vein. 10. Portion of the suspensory nan has observed, it is an arte- hepatis, or band of liver across the umbilical fissure. rial vein, in another sense, as it ment of obliterated ductus venosus to ascending vena is a vein to the hepatic artery, duct. 17. Hepatic artery. 18. Its branches. 19. Vena and an artery to the hepatic porta. 20. Its sinus, or division into right and left vein. 3. The excretory ducts Gall-bladder. 23. Its neck. 24. Lobulus quartus. 25. or biliary ducts. These are vena cava. 28. Curvature of liver to fit ascending colon. presumed to arise from acini, its right concave surface over renal capsule. 31. Portion communicating, according to of liver uncovered by peritoneum. 32. Inferior edge of coronary ligament in the liver. 33. Depression made by some, with the extremities of vertebral column. ligament in connexion with the round ligament. 11. Pons 12. Posterior end of longitudinal fissure. 13, 14. Attachcava. 15. Transverse fissure. 16. Section of hepatic branches. 21. Fibrous remains of ductus venosus. 22. Lobulus Spigelii. 26. Lobulus caudatus. 27. Inferior 29. Depression to fit right kidney. 30. Upper portion of 1 Philosophical Transactions for 1833, p. 711. the vena portæ; according to others, with radicles of the hepatic artery; whilst others have considered, that the radicles of the hepatic ducts have blind extremities, and that the capillary blood vessels, which secrete the bile, ramify on them. This last arrangement of the biliary apparatus was well shown in an interesting case, which fell under the care of Professor Hall, in the Baltimore Infirmary, and was examined after death in the author's presence. The particulars have been detailed, with some interesting remarks by Professor Geddings. In this case, in consequence of cancerous matter obstructing the ductus communis choledochus, the whole excretory apparatus of the liver was enormously distended; the common duct was dilated to the size of the middle finger: at the point where the two branches that form the hepatic duct emerge from the gland, they were large enough to receive the tip of the middle finger; and as they were proportionally dilated to their radicles in the intimate tissue of the liver, their termination in a blind extremity was clearly exhibited. These blind extremities were closely clustered together, and the ducts, proceeding from them, were seen to converge, and terminate in the main trunk for the corresponding lobe. At their commencement, the excretory ducts are termed pori biliarii. These ultimately form two or three large trunks, which issue from the liver by the transverse fissure, and end in the hepatic duct. 4. Lymphatic vessels. 5. Nerves, in small number, compared with the size of the organ, some proceeding from the eighth pair; but the majority from the solar plexus, which follow the course and divisions of the hepatic artery. 6. Supra-hepatic veins or vena cava hepaticæ, which arise in the liver by imperceptible radicles, communicating, according to common belief, with the final ramifications of both the hepatic artery and vena portæ; according to Mr. Kiernan occupying the centre of the lobules, and hence termed intralobular veins-venulæ intralobulares seu centrales. They return the superfluous blood, carried to the liver by these vessels, by means of two or three trunks, and six or seven branches, which open into the vena cava inferior. These veins generally pass, in a convergent manner, towards the posterior margin of the liver, and cross the divisions of the vena portæ at right angles. 7. The remains of the umbilical vein, which, in the foetus, enters at the horizontal fissure. This vein, after respiration is established, becomes converted into a ligamentous substance, called, from its shape, ligamentum rotundum or round ligament. It is difficult to describe the parenchyma or substance formed by these anatomical elements; and, although Fig. 335. Lobules of Liver. the term liver-coloured is used in common parlance, it is not easy to say what are the ideas attached to it. The views of Mr. Kiernan in regard to the intimate structure of the liver, which have been embraced by so many anatomists, may be understood by the accompanying illustrations, taken from his communications on the subject. The North American Archives of Medical and Surgical Science, for June, 1835, p. 157. |