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

by George S. Huntington

In Fig. 280 the lines of peritoneal reflection on the cephalic, dorsal and caudal surfaces of a human fœtal liver at term are shown.

We can now proceed to trace the reflection of the peritoneum from the liver to adjacent structures.

Begin with the caudal layer of the coronary ligament on the extreme right, where fusion with the corresponding cephalic layer produces the right triangular ligament. The caudal layer of the coronary ligament proceeds from right to left along the caudal margin of the non-peritoneal dorsal diaphragmatic surface of right lobe, being reflected along this line from the liver to the adjacent portions of the diaphragm and ventral surface of right kidney and suprarenal capsule (hepato-renal ligament). A small cephalic part of ventral surface of right suprarenal capsule lies above this line of reflection, is hence non-peritoneal and firmly connected with the liver just to the left of entrance of vena cava into the caval fissure. Continuing, the caudal layer of the coronary ligament crosses the ventral surface of the vena cava and turns, immediately to the left of the vein, at a right angle, ascending to form the left boundary of the Spigelian recess, being reflected along this line from the left margin of the caval fissure to the pillars of the diaphragm. Arrived at the opening of the central tendon permitting passage of vena cava into pericardium, and at the level of the entrance of the left hepatic vein into the cava, the peritoneum turns again at a right angle and runs from right to left, forming the cephalic limit of the Spigelian recess. Turning caudad along the fissure for the ductus venosus, as right leaf of that portion of the lesser omentum which is attached to this fissure and has preserved its sagittal position, the peritoneal line of reflection reaches the left extremity of the portal or transverse fissure. It now turns to the right following the fissure as the dorsal layer of the transverse segment of the lesser omentum, and becomes continuous, with the formation of a free right edge, with the ventral layer of the same membrane, passing from right to left, the two layers including between them the structures entering and leaving the liver at the transverse fissure (portal vein, hepatic artery, duct). Arriving at the left extremity of the transverse fissure the ventral layer of the transverse segment of the lesser omentum—as we practically trace it in the adult as a free membrane—turns directly into the left leaf of the sagittal segment attached along the fissure for the ductus venosus, and becomes continuous along the dorsal border of the left lobe with the caudal layer of the left coronary ligament. This direct continuity, as just stated, exists practically in the adult. From the development of the membrane, however, it will be seen that the ventral layer of the transverse lesser omentum, at the left extremity of the portal fissure, becomes continuous with the right layer of the primitive mesogastrium enclosing the umbilical vein. After surrounding this vein it is continued into the left leaf of the same membrane, which in turn passes into the left layer of the portion attached along the fissure for the ductus venosus.

This original connection can at times be traced very clearly in young specimens ([Fig. 279]), and occasionally is also still evident in the adult liver.

Usually, however, the round ligament of the adult and its investing peritoneum is buried so deeply in the umbilical fissure, or even bridged over in part by liver tissue, that the connection is not evident. The ventral layer of the transverse omentum then appears directly continuous with the left layer of the sagittal omentum attached along the fissure for the ductus venosus.

We can sum up the facts just considered as follows:

1. The rotation of the stomach from the sagittal into the transverse position, and the development of the umbilical and portal veins, rearrange the original sagittal plane of the lesser omentum, dividing it into two districts:

(a) Cephalic portion, remaining in the original sagittal plane, follows the fissure for the ductus venosus. With the incorporation of the Spigelian lobe in the adult dorsal or “posterior” surface of the liver, this segment of the omentum assumes a vertical direction, forming the left boundary of the Spigelian recess, being reflected from the fissure for the ductus venosus to the abdominal portion of the œsophagus and the part of the lesser curvature of stomach adjacent to the cardia.

(b) Distal caudal portion of the lesser omentum is twisted laterally and turned to the right by the change in the position of the stomach and the development of the structures connected with the liver at the transverse fissure. It is reflected from this fissure to the distal part of the lesser curvature and to the first portion of the duodenum. This transverse segment of the lesser omentum is a secondary derivative from the right leaf of the primitive membrane, produced by the enlarged area for entrance of umbilical and portal veins at the transverse fissure. It lies ventrad of caudal border of Spigelian lobe.