The Anatomy of the Human Peritoneum and Abdominal Cavity / Considered from the Standpoint of Development and Comparative Anatomy

by George S. Huntington

The lesser omentum therefore prolongs the plane of the stomach cephalad towards the liver and thus forms the continuation of the ventral boundary of the lesser peritoneal sac. We can now consider the line of its hepatic attachment in the light of the facts previously adduced, and combine the same with the line of gastric attachment to the lesser curvature. Fig. 282 shows the fœtal liver and stomach in their relative position in the dorsal view, and Fig. 283 gives the lines of the peritoneal reflections. The vertical segment of the omentum, occupying the fissure for the ductus venosus, passes to the cardiac part of the lesser curvature, its ventral layer covering the ventral and left side of the œsophagus, while its dorsal layer passes to the dorsal and right side of the œsophagus at its entrance into the stomach. The transverse segment of the omentum, attached on the liver to the portal or transverse fissure, accedes to the pyloric part of the lesser curvature. Of course the ventral and dorsal layers of the omentum are continuous with the serous visceral investment of the ventral and dorsal surfaces of the stomach.

Fig. 284 shows this right-angled course of the lesser omentum at the hepatic line of attachment in a preparation of the abdominal viscera hardened in situ, with the segment of the stomach between the cardiac and pyloric orifices removed. The arrow is passed behind the right free edge of the lesser omentum. This portion of the membrane is still intact, not having been disturbed by the removal of the body of the stomach, and includes between its layers the structures connected with the liver at the transverse fissure (duct, hepatic artery and portal vein). The lesser omentum is seen to be attached to the liver along the transverse fissure (Fig. 284, A) and along the fissure for the ductus venosus (Fig. 284, B), constituting the transverse and vertical segments above referred to, which pass into each other at the angle of junction between the transverse fissure (left end) and the fissure for the ductus venosus (Fig. 284, C). The caudal and left border of the Spigelian lobe is exposed by the division of the omentum, and the extent of the Spigelian or hepatic recess of the lesser peritoneal sac is shown. Fig. 285 shows the liver, stomach and lesser omentum of a Macaque monkey hardened in situ, and demonstrates still more conclusively that the uniform curve of the omentum along the lesser curvature of the stomach becomes a broken line at the hepatic attachment, the angle being placed at the left end of the transverse fissure at the point where the same encounters the fissure for the ductus venosus.

In Fig. 286 finally the hardened abdominal viscera of an adult human subject are shown in the ventral view with the lesser omentum incised. The cut through the lesser omentum exposes the hepatic recess of the lesser peritoneal cavity immediately to the left of the foramen of Winslow. Toward the right free margin of the omentum the divided portal vein, hepatic artery and duct are seen between the layers of the omentum imbedded in the pancreas and coursing behind the first portion of the duodenum on their way to the transverse fissure.

To the left of these structures the omental tuberosity of the pancreas projects above the level of the lesser curvature under cover of the secondary parietal peritoneum forming the dorsal wall of the lesser sac, while the lower edge of the Spigelian lobe appears in the upper angle of the incision.

If we remember that the liver is itself welded to the diaphragm between the layers of the coronary ligament ([Fig. 280]), it will become apparent that the serous surface of the Spigelian lobe forms part of the ventral wall of a peritoneal recess situated behind the lesser omentum, between this membrane and the diaphragm. Access to this recess, without the division of peritoneal layers, can only be obtained by passing from right to left, along the caudate lobe, between the vena cava behind, covered by parietal peritoneum, and the free right edge of the lesser omentum in front. (In the reverse direction of the arrow shown in [Fig. 284].) This hepatic or Spigelian recess of the lesser peritoneal cavity has categorically the following boundaries ([Figs. 282] and [283]):

Dorsal: Parietal peritoneum, reflected along the line CD, from the caudal layer of the coronary ligament to the diaphragm.

Ventral: Visceral peritoneum investing the Spigelian lobe and the gastro-hepatic omentum.

Right: Reflection of peritoneum along the line DE (caval fissure) to become the parietal peritoneum covering the diaphragm.

Left: Right layer of lesser omentum, reflected along the fissure for the ductus venosus (CB) to the cardiac portion of the lesser curvature, continuous with the dorsal layer of the lesser omentum reflected from the transverse fissure to the pyloric segment of the lesser curvature (AB).

We will presently see that certain relations of the vessels connected with the liver at the transverse fissure and of the duodenum prevent the finger, when passed from right to left behind the free right edge of the lesser omentum and along the caudate lobe of the liver, from proceeding downward at this point. A narrow channel of communication is thus formed between the Spigelian recess and rest of the lesser sac on the one hand, and the general greater peritoneal cavity on the other. This channel is the so-called foramen of Winslow.