THE BODY CAVITIES, DIAPHRAGM AND MESENTERIES 



Further Differentiation of the Mesenteries. Ligaments of the Liver. 

 We have seen (p. 181) that the cranial portion of the ventral mesentery 

 forms the mesocardium of the heart. In the ventral mesentery, caudal 

 to the septum transversum, the liver develops. From the first, it is 

 enveloped in folds of the splanchnic mesoderm; as the liver increases 

 in size, these give rise to its capsule and ligaments (Fig. 1 90 B) . Wherever 

 the liver is unattached, the mesodermal layers of the ventral mesentery 

 form its capsule (of Glisson), a fibrous layer covered by mesothelium, 

 continuous with that of the peritoneum (Fig. 1 90 JE?) . Along its mid-dorsal 

 and mid- ventral line the liver remains attached to the ventral mesentery. 

 The dorsal attachment between the liver, stomach, and duodenum is the 

 lesser amentum. This in the adult is differentiated into the duodena- 

 hepatic and gastro-hepatic ligaments. The attachment of the liver to 

 the ventral body wall extends caudally to the umbilicus and forms the 

 falciform ligament. 



In its early development the liver abuts upon the septum transversum, 

 and, in 4 to 5 mm. embryos, is attached to it along its cephalic and ventral 

 surfaces. Soon, dorsal prolongations of the lateral liver lobes, the 

 coronary appendages, come into relation with the septum dorsally and 

 laterally. The attachment of the liver to the septum transversum now 

 has the form of a cresent, the dorsal horns of which are the coronary 

 appendages (Fig. 200). This attachment becomes the coronary ligament 

 of the adult liver. The dorso-ventral extent of the coronary ligament 

 is reduced during development and its lateral extensions upon the dia- 

 phragm give rise to the triangular ligaments of each side. 



The right lobe of the liver, as we have seen, conies into relation along 

 its dorsal surface with the plica vena cavce in 9 mm. embryos (Figs. 199 

 and 200). This attachment extends the coronary ligament caudally 

 on the right side and makes possible the connection between the veins 

 of the liver and mesonephros which contributes to the formation of the 

 inferior vena cava. The portion of the liver included between the plica 

 venae cavae and the lesser omentum is the caudate lobe (of Spigelius). 



In a fetus of five months the triangular ligaments mark the position 

 of the former lateral coronary appendages. The umbilical vein courses 

 in a deep groove along the ventral surface of the liver, and, with the portal 

 vein and gall bladder, bounds the quadrate lobe. 



Changes in the Dorsal Mesentery. That part of the digestive canal 

 which lies within the peritoneal cavity is suspended by the dorsal mesentery, 

 which at first forms a simple attachment extending in the median sagittal 

 plane between body wall and primitive gut. That portion of it connected 

 with the stomach forms the greater omentum, the differentiation of which 

 has been described (p. 192). The mesentery of the intestine is carried 



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