OMENTA7 MESENTERIES, AND LIGAMENTS. By these terms we understand the sheets with two free surfaces, formed by duplication of the peritoneum and adhesion of the surfaces there by brought into apposition ; to describe these is our second proposition, and to that we now pass.
A parieto-visceral sheet is usually called a mesentery or a ligament ; a sheet with two free surfaces passing from one viscus to another is called an onientam.
The Jaleiform ligament of the liver has already been fully described. We agree with Cruveilhier that its main use is to conduct the umbilical vein from the navel to the antero posterior fissure of the liver. This, indeed, can hardly be called a use, especially in the adult; we would say mther that the existence of the falciform ligament necessarily results from the situation and course of the umbilical vein. It perhaps serves in some degree to retain the liver in situ, but it is not advanta geously placed with reg,ard to this office.
2'he coronary ligament of the liver is the name given to those portions of the peritoneum which leap across, so to speak, from the under surface of the diaphragm to the upper and posterior aspect of the liver. The anterior and posterior of these portions do not come in contact with one another in the middle, the liver being at that point in immediate contact with, and adherent to, the diaphragm ; but towards each side the two layers gradually approach each other, and at length conie contact and adhere, and are prolonged as folds bearing another name. The coronary lig-anient 1ixes the liver to the diaphragm, or rather the deficiency of peritoneal investment to the dia phragm and liver between its anterior and posterior portions allows the liver to adhere to the diaphragm, and small vessels and lym phatics to pass from the one to the other.
The triangular ligaments of the liver are the continuations of the layers of the coronary ligament, become adherent as above, leaping across from the rounded posterior corners of the liver to the nearest or postero-lateral portion of the upper concave abdominal parietes, that is to say, to the diaphragm. Their form is, as their name indicates, triang-ular; their anterior borders are free; their postetior and internal borders are attached, the former to the parietes, the latter to the liver. They help to keep the
liver in situ.
The lesser omentum has been partially de scribed above. Between its layers are included the vena portx, the hepatic artery, the gall duct, and the hepatic plexus, along its free border ; and the pyloric and coronariaventriculi arteries, with accompanying veins and nerves, along its g,astric attachment. Except in the course of these vessels, it is a thin transparent membranous sheet, with a very small amount of strength. The vessels destined for its own proper nutrition are extremely few and small. With regard to its use, Cruveilhier thinks that it is a true mesentery of the stomach, mesogas trium, but on this point we would offer the following remarks. One characteristic of a mesentery is, that it retains its bowel in situ, and this office the lesser omentum doubtless partially performs towaids the stomach ; but another characteristic of a mesentery is, that it gives passage to the arteries and veins of the bowel to, which it belongs, and this office the lesser omentum performs, not for the stomach, but for the liver. It is the spier& omentum, or that part of the great omentum whereupon the spleen is sessile, extending between the parietal line of attachment running from the cardia to the left bend of the colon, and the fundus of the stomach, that conducts the prin cipal gastric vessels, as the coronaria ventriculi, vasa brevia, and gastro-epiploica sinistra,-from the parietes to the stornach. The splenic omen tum fulfils indeed both these offices towards the stomach, and occupies with regard to it the position of a parieto-visceral fold,a relation still rnore characteristic of a mesentery. We there fore are inclined to consider the splenic omen tum as the mesogastrium ; and some facts in cornparative anatomy, (figs. 490, 491,) as well as that mentioned above, of its affording transit to the hepatic vessels, seem to indicate that the lesser omentum is the mesentery of the gall-duct and liver..