The most curious circumstance connected with the healing of an artificial anus is, that the position of the united intestines and the intervening infundibulum or funnel behind the cicatrix is not permanent. "It is," says Scarpa,* " a certain fact confirmed by a very great num ber of observations, that after the separation of the gangrene the two sound segments of intes tine retire gradually beyond the ring towards the cavity of the abdomen, notwithstanding the adhesion which they h ave con tracted wi th the neck of the sac, whether this is caused by the tonic and retractile action of the intestine itself and of the mesentery, or rather by the puckering of the cellular substance, which unites the hernial sac to the abdominal parietes within the ring. And this phenomenon is likewise constant and evident even in herniae not gangrenous, but merely complicated with fleshy adhesions to the neck of the sac, and therefore irreducible. In these herniae, the immediate cause of stran gulation being removed, the intestine, together with the hernial sac, gradually rises up towards the ring, and at last is concealed behind it." The same fact has been observed by Dupuy tren,* who attributed it to the continued action of the mesentery on the intestine. Many indi viduals who had been cured of artificial anus without operation returned to the Hotel Dieu at very remote periods, and died of diseases having no relation to the original complaint. The parts were curiously and carefully examined, and the intestine, instead of being fixed to the walls of the belly, was found free and floating within the cavity. There could be no doubt of the identity of the individuals, and moreover a fibrous cord was seen extended from the point of the wall of the abdomen which corresponded with the former artificial anus, to the intestine. This cord, some lines in diameter and some inches in length, thicker at its extremities than in the middle, covered by peritoneum, and formed entirely by a cellular and fibrous tissue without any cavity, was evidently produced by the progressive elongation of the cellular membrane that had united the intestine to the wall of the abdomen ; and the cause which had occasioned this elongation was nothing else than the traction exercised by the mesentery on the intestine in the different motions of the body during life.
Having now endeavoured to describe gene rally the circumstances or conditions under which protrusions of the abdominal viscera may exist, I proceed to consider the peculiarities that arise from situation, premising that it is not my intention to enter very minutely into the descriptive anatomy of those several situa tions in their normal or healthy states, but only in reference to and in connexion with the ex istence of the disease under consideration.
Inguinal hernia.—When a viscus is pro truded through one or both of the apertures termed rings, situated at the anterior and infe rior part of the abdomen, near the fold of the groin, but above Poupart's ligament, the hernia is termed inguinal. It may exist, therefore, in three different conditions. 1. Where the in testine has been pushed through the internal ring only, and is lodged in the inguinal canal : it then appears as a small, round, firm, and moderately elastic tumour. 2. Where it has passed through the internal ring, through the inguinal canal, through the external ring, and dropping down into the scrotum of the male or the labium pudendi of the female, appears as a larger and more yielding tumour, of a pyrami dal shape, the apex of the pyramid being di rected towards the anterior superior spinous process of the ilium. As these are but different stages of the same disease, both come under the appellation of hernia by the oblique descent. But, 3, when the viscus has been forced through the parietes immediately behind the external ring, and passes out through that natural aperture only, it is then for obvious reasons termed the hernia by direct descent; and although the external characters of the tumour are not always such as to point out the peculiar nature of this protrusion, yet the relative posi tion of the intestine with respect to adjacent parts must be somewhat different in these seve ral cases, a difference that will be found to be of some practical importance.
The peritoneal sae, as viewed internally in the direction of the iliac and inguinal regions, is described by Scarpa as being divided into two great depressions at each side, the medium of partition being the ligament into which the umbilical artery of the foetus had degenerated, together with the fold of peritoneum raised by that ligament. Of these fosse the superior or external is the larger and deeper; it is that within which the intestines are collected when strongly compressed by the abdominal muscles and by the diaphragm in any violent exertion ; and from it inguinal hernia is most frequently protruded, as the ligament and duplicature of the peritoneum prevent the compressed viscera lodged in this fossa from removing out of it to descend into the pelvis. The situation of the umbilical artery varies considerably : some times it is close upon the internal border of the internal ring, in other subjects at the distance of half an inch from it, or even more; but it is nlways at the pubic side of the epigastric ves sels. Thus, in its direction upwards and in wards towards the umbilicus it crosses ob liquely behind the inguinal canal : all hernite, therefore, by the oblique descent pass out from the external or superior abdominal fossa, while those by the direct are in relation to and are protruded from the inferior or internal. Inde pendent of this configuration there is nothing in the peritoneal cavity as viewed from within, to determine the occurrence of hernia at one place rather than at another. The membrane is in all parts equally smooth and polished, equally strong,• tense, and resisting. This, however, is not the case with respect to the muscular and tendinous walls of the abdomen, which vary very considerably in density and strength in different situations, and in these qualities dissection shews that the hypogastric or inguinal regions are the most deficient and therefore most disposed to permit of the occur rence of hernia.
In prosecuting the dissection from within (which is by far the most satisfactory manner), the peritoneum may be detached by the fingers or by the handle of the knife in consequence of the laxity of the cellular tissue connecting it to the adjacent external structures. The Macke transversalis then comes into view, and in it the aperture termed the internal ring, through which the spermatic cord in the male, and the round ligament in the female are transmitted. This aponeurosis varies in density and thick ness in different individuals : it is continuous with the fascia iliaca, and is connected with the posterior edge of Poupart's ligament : it is denser and stronger externally, and becomes weaker and more cellular as it approaches the mesial line. Where the internal oblique is muscular, the connexion between it and the fascia transversalis is extremely lax, cellular, and easily separable ; but after it becomes tendi nous, the union is much more intimate, and the fibres of the one can scarcely be distinguished from those of the other unless by the difference of their direction. In most subjects the internal ring is very indistinct, its size, shape, and direc tion being in general determined rather by the knife of the anatomist than by nature. So far as the fascia is concerned, the external inferior border of the ring is its strongest part, but its internal edge seems to be the stronger as it is supported by the epigastric vessels, and some times by the remnant of the umbilical artery. Its size is about an inch in length, half an inch in breadth ; its shape oval ; and the direction of its longest diameter perpendicular or slightly inclining from above downwards and outwards.