Fig. 3. The surface, C. R., E. L., exposed by removal of skin and superficial fascia to display the tendons of the external oblique muscles and adjacent parts. A. The superficial fascia—lost over the position of Chang’s umbilical pouch. B, C. Supplemental layers of fibrous tissue of Eng not seen in Chang; B is a continuation toward Eng of aponeurotic fibres having a source from the linea alba of Chang; C is independent of the former, and is continuous with the deep pectoral fascia. D. The interlacing of fibres on tendon of external oblique muscle of Chang. E. The linea alba of Chang, beginning at C. R. F. Its continuation to E. L., and insertion upon the ensiform cartilage.
Turning down the superficial layer, the aponeurosis of the external oblique muscle was exposed (Fig. [3]). A marked contrast was exhibited in the two sides of the band. In Chang the parts were normal so far as they were exposed—the characteristic apertures for the escape of small vessels being abundant and conspicuous. In turning down the superficial fascia in Eng (Fig. [3], A), it was found to be continuous at its lower portion with an aponeurotic layer (Fig. [3], B), which extended toward the median line, where it was continuous with the linea alba of Chang. In addition to this, a second layer (Fig. [3], C), analogous in position to a deep layer of the superficial fascia, which was entirely independent of Chang, extended over nearly the whole of Eng’s division, and was particularly well defined over the fibres of origin of the external oblique muscle. This was continuous with the deep layer of the superficial fascia which passed over the entire side of Eng’s thorax.
Toward the middle of the band this layer gradually lost its distinctive features, and was firmly incorporated with the tendon of the external oblique muscle. A number of fibres corresponding to it extended in inseparable intimacy with this tendon. These were gradually lost as they approached the linea alba of Chang, and the parts being in position these fibres were at their lower portion covered in by the aponeurotic extension of the linea alba already mentioned.
On Chang’s side, as we have seen, the parts comparable to these accessory layers were absent. There was no line of demarcation between the tendon of the oblique and the aponeurotic attachment of the pectoralis. The tendon of the external oblique presented a different appearance from the normal one in a more extensive interlacing of fibres of the linea alba with the tendon.
The part termed above the linea alba of Chang (Fig. [3], E), has already been indicated through skin and superficial fascia. As can be seen, this band of fibres, having its origin from the middle line of the abdomen of Chang, was found to be a direct continuation of the linea alba. It was remarkable in not being inserted into the ensiform process of Chang, but into that of Eng, and in giving off the aponeurotic outshoot B, already noticed, as well as in having a diffused point of insertion into Eng’s tissue as in the ensiform cartilage (F). In a word, the linea alba approaches the surface C. R., E. L. from C. R. below, and is inserted into E. L. above.
IV. Organs Of Abdomen as observed in position through the Incisions.
Limited incisions being alone permitted, the large vessels of the abdomen were sought for in the process of embalmment, believing, as we did, that the procedures of securing them would enable us, by extending the cuts from below upward, to fairly open the abdomen and examine thereby the interior of the band.
In each body, therefore, an incision six inches long (Fig. [2], ab, cd) was extended from the centre of the right iliac region to the centre of the right hypochondriac region. This was subsequently joined by an oblique incision passing from the upper end of the first mentioned to the lateral border of the ensiform cartilage at its base. This incision measured 7-1/2 in. The lower end of the vertical incision was met by a horizontal one passing to the centre of the hypogastric region, and measuring 3-1/4 in.
Through these incisions were studied (1) the umbilical ligaments and (2) the abdominal viscera.