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82 COMMENTARY ON PLATES 32, 33, & 34.

In this stage of the hernia, its situation in respect to the epigastric artery is truly external, and in respect to the sper­matic vessels, anterior, while the protruded intestine itself is separated from actual contact with either of these vessels by its proper sac. The bubonocele, pro­jecting through the internal ring at the situation marked F, (Plate 33,) midway between A, the anterior iliac spine, and I, the pubic spine, continues to increase in size; but as its further progress from behind di­rectly forwards becomes arrested by the tense resist­ing aponeurosis of the external oblique muscle, h, it changes its course obliquely inwards along the canal, traversing this canal with the spermatic vessels, which still lie behind it, and, lastly, makes its exit at the external ring, H. The obliquity of this course, pur­sued by the hernia, from the internal to the external ring, has gained for it the name of oblique hernia. In this stage of the hernial protrusion, the only part of it which may be truly named external is the neck of its sac, F, for the elongated body, G, of the hernia lies now actually in front of the epigastric artery, P, and this vessel is separated from the anterior wall of the canal, H h, by an interval equal to the bulk of the hernia. While the hernia occupies the canal, F H, without projecting through the external ring, H, it is named "incomplete." When it has passed the exter­nal ring, H, so as to form a tumour of the size and in the situation of f g, it is named "complete." When, lastly, the hernia has extended itself so far as to oc­cupy the whole length of the cord, and reach the scrotum, it is termed "scrotal hernia." These names, it will be seen, are given only to characterise the several stages of the one kind of hernia--viz., that which commences to form at a situation external to the epigastric artery, and, after following the course of the spermatic vessels through the inguinal canal, at length terminates in the scrotum.

The external inguinal hernia having entered the canal, P, (Plate 32,) at a situation immediately in front of the spermatic vessels, continues, in the several stages of its descent, to hold the same relation to these vessels through the whole length of the canal, even as far as the testicle in the scrotum. This hernia, how­ever, when of long standing and large size, is known to separate the spermatic vessels from each other in such a way, that some are found to lie on its fore part--others to its outer side. However great may be the size of this hernia, even when it becomes scrotal, still the testicle is invariably found below it. This fact is accounted for by the circumstance, that the lower end of the spermatic envelopes is attached so firmly to the coats of the testicle as to prevent the hernia from either distending and elongating them to a level below this organ, or from entering the cavity of the tunica vaginalis.

The external form of inguinal hernia is, compara­tively speaking, but rarely seen in the female. When it does occur in this sex, its position, investments, and course through the inguinal canal, where it accompa­nies the round ligament of the uterus, are the same as in the male. When the hernia escapes through the external abdominal ring of the female groin, it is found to lodge in the labium pudendi. In the male body, the testicle and spermatic cord, which have carried before them investments derived from all the layers of the inguinal region, have, as it were, already marked out the track to be followed by the hernia, and prepared for it its several coverings. The mus­cular parietes of the male inguinal region, from which the loose cremaster muscle has been derived, have by this circumstance become weakened, and hence the more frequent occurrence of external inguinal hernia in the male. But in the female, where no such pro­cess has taken place, and where a cremaster does not exist at the expense of the internal oblique and trans­verse muscles, the inguinal parietes remain more compact, and are less liable to suffer distention in the course of the uterine ligament.

The internal inguinal hernia takes its peritonaeal covering (the sac) from the inner fossa, Q R, Plate 32, internal to the epigastric artery, and forces directly forwards through the external abdominal ring, carrying investments from each of such structures as it meets with in this locality of the groin.

COMMENTARY ON PLATES 32, 33, & 34. 83

As the exter­nal ring, H, Plate 34, is opposite the inner peritonaeal fossa, Q R, Plate 32, this hernia, which protrudes thus immediately from behind forwards, is also named direct. In this way these two varieties of hernia, (the external, Plate 33, and the internal, Plate 34,) though commencing in different situations, P and R, Plate 32, within the abdomen, arrive at the same place--viz., the external ring, H, Plates 33 and 34. The coverings of the internal hernia, Plate 34, though not derived exactly from the same locality as those which invest the cord and the external variety, are, nevertheless, but different parts of the same struc­tures; these are, 1st, the peritonaeum, G, which forms its sac; 2nd, the pubic part of the fascia transversalis; 3rd, the conjoined tendon itself, or (according as the hernia may occur further from the mesial line) the cremaster, which, in common with the internal oblique and transverse muscles, terminates in this tendon; 4th, the external spermatic fascia, derived from the margins of the external ring; 5th, the superficial fascia and integuments.

The coverings of the internal inguinal hernia are (as to number) variously described by authors. Thus with respect to the conjoined tendon, the hernia is said, in some instances, to take an investment of this structure; in others, to pass through a cleft in its fibres; in others, to escape by its outer margin. Again, the cremaster muscle is stated by some to cover this hernia; by others, to be rarely met with, as forming one of its coverings; and by others, never. Lastly, it is doubted by some whether this hernia is even covered by a protrusion of the fascia transver­salis in all instances. [Footnote]

[Footnote: Mr. Lawrence (Treatise on Ruptures) remarks, "How often it may be invested by a protrusion of the fascia transversalis, I cannot hitherto determine." Mr. Stanley has presented to St. Bartholomew's Hospital several specimens of this hernia invested by the fascia. Hesselbach speaks of the fascia as being always present. Cloquet mentions it as being present always, except in such cases as where, by being ruptured, the sac protrudes through it. Langenbeck states that the fascia is constantly protruded as a covering to this hernia: "Quia hernia inguinalis interna non in canalis abdominalis aperturam internam transit, tunicam vaginalem communem intrare nequit; parietem autem canalis abdominalis internum aponeuroticum, in quo fovea inguinalis interna, et qui ex adverso annulo abdom­inali est, ante se per annulum trudit." (Comment, ad illust. Herniarum, &c.) Perhaps the readiest and surest explanation which can be given to these differences of opinion may be had from the following remark:--"Culter enim semper has partes extricat, quae involucro adeo inhaerent, ut pro lubitu musculum (membranam) efformare queas unde magnam illam inter ana­tomicos discrepantiam ortam conjicio." (Camper. Icones Herniarum.)]

The variety in the number of investments of the internal inguinal hernia (especially as regards the presence or absence of the conjoined tendon and cre­master) appears to me to be dependent, 1st, upon the position whereat this hernia occurs; 2nd, upon the state of the parts through which it passes; and 3rd, upon the manner in which the dissection happens to be conducted.

The precise relations which the internal hernia holds in respect to the epigastric and spermatic vessels are also mainly dependent (as in the external variety) upon the situation where it traverses the groin. The epigastric artery courses outside the neck of its sac, sometimes in close connexion with this part--at other times, at some distance from it, according as the neck may happen to be wide and near the vessel, or nar­row, and removed from it nearer to the median line. At the external ring, H, (Plate 34,) the sac of this hernia, g, protrudes on the inner side of the spermatic vessels, f; and the size of the hernia distending the ring, removes these vessels at a considerable interval from, I, the crista pubis. At the ring, H, (Plate 34,) the investments, g f, of the direct hernia are not always distinct from those of the oblique hernia, g f, (Plate 33); for whilst in both varieties the intestine and the spermatic vessels are separated from actual contact by the sac, yet it is true that the direct hernia, as well as the oblique, may occupy the inguinal canal.

84 COMMENTARY ON PLATES 32, 33, & 34.

It is in relation to the epigastric artery alone that the direct hernia differs essentially from the oblique variety; for I find that both may be enclosed in the same structures as invest the spermatic vessels.

The external ring of the male groin is larger than that of the female; and this circumstance, with others of a like nature, may account for the fact, that the female is very rarely the subject of the direct hernia. In the male, the direct hernia is found to occur much less frequently than the oblique, and this we might, a priori, expect, from the anatomical disposition of the parts. But it is true, nevertheless, that the part where the direct hernia occurs is not defended so com­pletely in some male bodies as it is in others. The conjoined tendon, which is described as shielding the external ring, is in some cases very weak, and in others so narrow, as to offer but little support to this part of the groin.

DESCRIPTION OF THE FIGURES OF PLATES 32, 33, & 34.

PLATE 32.

A. That part of the ilium which abuts against the sacrum.

B. The spine of the ischium.

C. The tuberosity of the ischium.

D. The symphysis pubis.

E. Situation of the anterior superior iliac spine.

F. Crest of the ilium.

G. Iliacus muscle.

H. Psoas magnus muscle supporting the spermatic vessels.