3d. According to Richet there is no inferior wall, unless with Blandin we regard the perineal floor as such., If this opinion of Richet is true from a surgical point of view, it is not from the obstetrical, for all ob stetricians consider the perineal floor as the floor of the pelvis.
4th. There only remains the antero-lateral wall; and this deserves our whole attention.
Considered as a whole, it forms a sort of contractile band, of a lozenge shape. It extends from the edge of the last ribs, laterally, to the iliac crests, and from the notch which the ribs form in leaving the sternum to that formed by the anterior iliac spines. It may be divided into two sec tions: the anterior, limited by the external edge of the recti muscles; the lateral limited at the back by the anterior edge of the quadratus lum borum and the sacro-lumbalis muscles.
IL Anterior Abdominal Region.
It is bounded externally by the external edge of the rectus muscle, above by the ensiform cartilage, below by the pubic iymphysis. Proceed ing from without inward it is formed by: 1st. The skin, which is very loosely attached to the subjacent tissues, except at the level of the umbilicus.
2d. The sub-cutaneous layer, which is divided into two laminw or faseim, which cross those ()lithe opposite side at the median line, and ad here to the linea alba.
?d. The linea alba: an aponeurosis formed by the union of fibrous layers which extend from the oblique and transverse muscles of the abdomen. It is really composed of four layers, one proceeding from the external oblique muscle, two from the aponeurosis.of the internal oblique, which is in fact formed of two layers, and, finally, one proceeding from the transversalis muscle.
Having anived at the external edge of the recti these layers separate; that of the external oblique, uniting with that of the internal oblique, passes in front of the rectus muscle, while the deep layer of this last muscle, united to that of the transversalis, passes backward. The rectus muscle is thus enclosed in a solid and resisting aponeurotic sheath.
This sheath is, however, incomplete below. There the layer of the internal oblique muscle becomes thinner, until it only forms a mem branous sheath; but it is replaced by another fibrous lamina, the fascia tranversalis.
At the internal edge of the rectus muscle, these four layers again unite, and form a solid resisting membrane, the fasciculated fibres of which pass obliquely towards the median line, where they cross those of the opposite side at more or less acute angles. This is the lines alba.
4th. The recti muscles, inclosed within the aponeurotic sheath which has just been described.
4th. The sub-peritoneal cellular tissue.
6th. The peritoneum and the abdominal cavity.
Here also are found: arteries, proceeding from the internal mammary, which inosculate from above downward with the epigastric, and laterally with the terminal branches of the lumbar and intercostal arteries; nerves; lymphatics going to the axillary and inguinal glands; some to the glands which surround the iliac artery, and, finally, nerves from the last dorsal and lumbar branches.
The umbilicus is the cicatrix resulting from cutting the umbilical cord.
Lateral Abdominal Region.
It is bounded in front by the external edge of the rectus muscle, behind by the anterior edge of the latissimus dorsi, the sacro-lumbalis and the quadratus lumborum; above by the ribs; below by the iliac crest and femoral arch. It is remarkable for containing the inguinal canal.
Richet divides it into two parts: a superior lateral region of the ab domen, and inferior lateral, or ilio-inguinal region.
Superior Lateral Region.
Proceeding from without inward we find: The skin; the subcutaneous layer, which,is divided into a superficial lamina, or fascia superficialis, and a deep lamina. An aponeurosis, which covers the muscular fibres; the external oblique; the internal oblique; the transversalis; a cellular layer; the fascia propria transversalis; the peritoneum; the lower intercostal and lumbar arteries; some veins; nerves from the anterior branches of the last intercostals, and some ab dominal branches of the lumbar plexus; finally, lymphatics, which pro ceed to the axillary, inguinal, iliac, lumbar and intercostal glands.