V. Interior of Band.
We here describe (1) the hepatic pouches; (2) the umbilical pouches; (3) the vascular structures of the band; (4) the diaphragms; (5) the ensiform cartilages.
1. The hepatic pouches.—The photograph (Fig. [2]) indicates the position of the right lobe of Eng’s liver in the right hypochondriac region. The right lobe of Chang is of course not seen in the figure, since it lies on the side of the body which is not in the field of vision. It must follow from the rights and lefts of the two individuals being opposites that, in drawing a line between the livers (which, as already seen, occupy normal positions as to right and left) across the band, such a line will be diagonal to the axes of the ensiform cartilages; Chang’s half of the band having the line enter the band from his “right,” Eng from his “left.” It will also follow that any pouches of peritoneum which might accompany this line will pursue a similar direction—be on the same plane—be right or left with respect to the axis of that plane. Now it was actually demonstrated that such a line did extend between the livers, and was accompanied by such peritoneal pouches. These pouches were termed the hepatic pouches, and may be described as follows:—
Chang.—The subject lying on the table with rights and lefts determined as in the acquired position, the finger could be inserted behind the suspensory ligament (Fig. [7]) in a pouch lying directly beneath the ensiform cartilages, into which passed an extension of liver-like tissue.
Eng.—This fact could not be well demonstrated in Eng in this position, but is well seen in Fig. [8].
It follows that the two hepatic pouches are on nearly the same plane, and that each approaches the central point of the band diagonally from the right side of the subject with whose abdominal cavity it is continuous.
2. The umbilical pouches.—Beneath the hepatic pouches, and between them and the inferior border of the band, were two pouches which, from their association with the round ligament, have been termed the umbilical pouches.
When the finger was passed toward the band from the abdomen of Chang, and following the peritoneum of the anterior wall of the abdomen, it passed into a pouch of the band directly over the skin covering, across the band, over the umbilicus, and was received within the folds of the suspensory ligament of the liver of Eng. This pouch was so superficial that while the finger was in the pouch any motion of the finger was readily followed by the observer.
In the same way as above, if the finger was introduced behind the suspensory ligament of Eng, it slipped into a pouch which passed across the median line of the band, and was received within the folds of the suspensory ligament of the liver of Chang.
There were then two pouches communicating with the two abdominal cavities, arranged one above another in the band, Chang’s being the lower of the two. No remains of an umbilical vein were detected, nor was there any communication between the pouches and the umbilicus. It has already been noticed that the round ligament of each liver passed from the longitudinal fissure to a scar on the anterior wall of the abdomen near the band. It was not, therefore, within the round ligaments, but the folds of the suspensory ligaments, that the pouches were found.
Eng’s pouch measured 2-1/2 in. From edge of Chang’s suspensory ligament to end of hepatic pouch measured 3 in.
Extending across the band, about midway between the properties of the two individuals, was a septum. It was attached above and below to the respective boundaries of the band, and along its entire length was incorporated with its two peritoneal cavities, so that when in the course of the dissection of the “posterior” surface of the band the peritoneal covering of the band was displayed, several large lobules of fat were seen lying to Eng’s side of the septum.[[4]]
It will be seen that Fig. [8] represents the band opened to display the pouches with the septum. The lower end of the septum is fixed near the scar of the umbilicus, and holds an immobile position over the umbilical pouches. At this point it is free from fat. But as it extends over the hepatic pouches it is more pliant. This portion of the septum has been carried a little to Chang’s side of the band to display the entire length of the hepatic pouch of Eng.
Figs. [9] and [10] are designed to exhibit the appearances presented in securing views of the septum from its sides. Fig. [9] is the side toward Chang, and Fig. [10] is the side toward Eng.
Fig. 8. The surface, C. R., E. L., showing the interior of band by free division of the aponeuroses seen in Fig. [7], and their underlying peritoneal attachments. A. The orifice of umbilical pouch of Eng. B. The orifice of umbilical pouch of Chang, showing connection with suspensory ligament of Eng. C. The fenestrated umbilical pouch of Eng passing between the folds of the suspensory ligament of Chang. D. Suspensory ligament of liver of Eng. E. Hepatic tract. F. Hepatic pouch of Eng. G. The septum.
The pouches and septum were now removed and the position of the hepatic tract determined. It rested upon the incurved borders of the ensiform cartilages (see Fig. [15]), and as the subject lay on the table with the “posterior” surfaces of the band exposed (Fig. [11]) the hepatic tract was slightly arched. It measured three inches in length, was compressed, and measured six lines wide and three lines thick. The tract arose from the livers at the same point—namely, directly above the longitudinal fissure, having more fulness on the side of the right than of the left lobe. The round ligament, as it passed out of the longitudinal fissure of each liver, was placed beneath and a little to the left of the tract.
Fig. 9. The septum viewed from Chang’s side. A. The orifice of umbilical pouch of Chang. B. The orifice of the hepatic pouch of Chang. C. Suspensory ligament of Chang containing umbilical pouch of Eng.
Fig. 10. The septum viewed from Eng’s side. A. The orifice of the umbilical pouch of Eng. B. The orifice of the hepatic pouch of same. C. Suspensory ligament of Eng containing the umbilical pouch of Chang.
3. The vascular structures of the band were as follows:—
The livers being united, it was found that a colored injection thrown into the portal vein of Chang passed into the liver of Eng. A careful dissection of the blood vessel[blood vessel] (Fig. [11], C) proved it to be a terminal twig of the portal system of Chang. It was of the thickness of a No. seven catheter, French scale, gradually diminished in size, and was lost toward the centre of the band. It did not pass as such across the band, but appeared to break up into minute branches before reaching the liver of Eng. At the same time there was undoubted distension of the portal capillaries with the colored fluid under the capsule of the dorsal surface of the right lobe of Eng’s liver, one and one-half inches from the band. Examination of the branches of the mesenteric veins of Eng revealed the curious fact that some of them had received the injection. This had not been transmitted through the liver, for the portal vein at the transverse fissure was empty, but through a distinct extra-hepatic portal track, which was found lying under the peritoneum beneath the position of the hepatic pouches, and in association with the umbilical pouches. This vessel began by relatively large radicals towards Chang’s side, became larger as these encroached on Eng’s side, and was finally received within the portal system of Eng’s body, as a tributary to its mesenteric vein.
Fig. 11. The surface, C. R., E. L., with pouches removed to display the hepatic tract. A. Liver of Chang. B. Liver of Eng. C. Portal vessel of Chang. D, D. Minute branches of hepatic artery. E. Subcutaneous fat of surface, E. R., C. L.
No other vessels were met with in the band excepting a few insignificant branches of the hepatic artery, and the terminal twigs of the right internal mammary of Eng. The former vessels are marked D, D, Fig. [11]. The latter vessel terminated by piercing the diaphragm, and giving ultimate filaments to the integument of the “front” of the band as shown in Fig. [12].
Fig. 12. The surface, C. R., E. L., with pouches, hepatic tract, and peritoneal attachments removed to display the diaphragms. A. Subcutaneous fat of surface, E. R., C. L. B, C. Symmetrical muscular fasciculi. D. Fasciculi of Eng crossing the median line of the band.
4. The diaphragms.—The subject being in the same position as in Fig. [2], the livers were removed, the peritoneal coverings dissected from the band, and the diaphragms exposed (Fig. [12]). The point (A), marked by the terminal twigs of the right internal mammary of Eng, indicated the “anterior” of the band. A broad slip of fibres of Chang (B) was seen to pass across the median line, and to be inserted into the left border of the ensiform cartilage of Eng (Fig. [17]). This arrangement would appear to correspond to the smaller collection of fibres (C) belonging entirely to Eng. A second arrangement of fibres was seen above those just indicated, immediately under the cartilages (D). This appeared to arise from the border of the cordiform tendon of Eng by two distinct narrow slips, which crossed the median line to be inserted dispersedly on the diaphragm of Chang.
Fig. 13. The peritoneal linings of the anterior walls of both abdominal cavities. A, A. The summits of the bladders. B, B. The umbilical ligaments. C, C. The nodules of fat at the parietal scar. D, D. The isolated lobules of fat.
5. The ensiform cartilages.—After removing the diaphragms the cartilages were exposed. They may be described as follows:—
Chang.—The cartilage measured 2-1/2 in. wide, and 8 in. in length along its axis. The right border was very prominent, and projected 1/2 in. beyond the limit of the corresponding border in Eng. It was almost in close contact with the cartilage of the eighth rib; it was very robust, with upper surface convex, under surface nearly plane. The left lateral border was 2-1/2 in. in length, right lateral border 11 lines in length. The former was marked by three tubercles of about equal size. One situated about 1 in. from the sternal origin; the other about 2 in. from the same point; the third at its extreme anterior border. None of these were robust, or presented any of the thickening noticed on the right side. The middle of these tubercles was on a line with that of the posterior tubercle. The junction of the ensiform process with the sternum was not marked by the eminence characterizing the similar point in Eng.
Eng.—The cartilage differed from that of Chang in being 2-1/3 in. wide, 11 lines in length of axis. The left lateral border was abruptly deflected downward, and did not present the transverse smooth projection noticed in Chang. This deflection was almost at right angles to the dorsal surface, acuminate inferiorly, and presenting a straight surface toward Chang, and an oblique one toward the ribs. The length of left lateral border was 1 in. The right lateral border, 1-1/3 in. in length, presented a smooth sub-rounded edge without tubercles, and terminated in a free rounded border on a plane a little above that of Chang. On the whole this border was more robust than that of Chang. On the dorsal aspect of the process near its base was seen the rounded eminence described in the account of the external appearances (see page 7).
A comparison between the two ensiform cartilages shows that in Chang the anterior border was longer than in the right in Eng. In other proportions Eng’s was equal if not larger than Chang’s, and was more robust.
Fig. 14. A section of both ensiform cartilages, C. R., E. L. A. Chang’s cartilage. B. Eng’s cartilage. C. The synchondrosis. D. The bursa-like sac covering the same. E. An opening in the sac. F. Transversalis muscle of Eng. G. Transversalis muscle of Chang.
The union between the cartilages was of the character of a symphysis. The union was very intimate along the border E. L., C. R., “posterior” (Fig. [14]); the exposure of the junction by a delicate transverse cut showed a close union between the cartilages, thus constituting this part of the band a synchondrosis. That this, however, did not characterize the entire line of apposition was at once seen by turning to the border E. R., C. L. (“anterior”), where an interval, two lines in width, was seen between the cartilages, an interval which had been evidently susceptible of variation during life. This interval extended across one-fourth the width of the band. The portion of the band between the parts as above indicated, was occupied by a bursa-like sac (Fig. [14], D), which was opened by a minute orifice (E) to display its true nature. This sac was crossed above by a stout band of fibrous tissue (Fig. [15], A) an inch in width. Beneath, the sac was protected by a less well-defined band of the same width as the upper ligament, and which crossed between the two processes, to be lost in the perichondrium.
Fig. 15. Upper surface of ensiform cartilages. A. The upper ligament uniting the cartilages.
Viewing the cartilages as the constituent parts of the band, we found the border C. L., E. R., the “anterior,” to be longer than C. R., E. L., the “posterior.” C. L., E. R. was a convex, nearly even border, C. L. being larger than E. R., with a gaping interval placed nearer Eng than Chang. C. R., E. L. was an irregular, uneven border, without interval, C. R. being smaller than E. L., and placed to the outer side.