1002 



THE ORGANS OF DIGESTION 



In man and in must of tlic hi^trher mammals not only is the meso-gaster 

 (m-g, fig. 602, A) involved in the bulging which forms the great omentum, but 

 some part of the transverse meso-eolon (M-r) l)ecomes involved also. This depends 

 upon the close connection which exists between the right end of the transverse colon 

 and the duodenum. It will be seen from figs. 600 and 602, A, that but a little 

 extension of the bulging of the membrane is needed for the transverse meso-colon 

 to become involved. In such case the anterior layer of the great omentum will 



Fig. 603. — Kklatiox of Great Omentum to Transverse Colon, 



; TRANS. MESO-COLON \ 



appear to come oflP from the greater curvature of the stomach, while the posterior 

 layer will return to the transverse colon and will become continuous wdth the 

 meso-colon (figs. 602, C, and 603, A). In the adult man this arrangement usually 

 extends throughout the greater part of the width of the great omentum. It is in 

 all instances to be observed in all that part of the great omentum which is about 

 and to the right of the middle line. In the foetus (as in the lower primates) the 

 posterior layer of that part of the great omentum Avhich is quite to the left of the 



Fig. 604. — Transverse Section of the Abdomen at the Level of the Foramen 



OF WiNSLOW. 



middle line is clear of the transverse meso-colon. and is oln'ioush- derived from the 

 meso-gaster solely (figs. 602, B, and 603, B). 



This difference between the right and the left extremities of the transverse 

 meso-colon and omentum can sometimes be made out in the adult man. 



The term 'the lesser cavity of the peritoneum' is ajjplied to the cavity formed 

 by this protrusion of the peritoneum. The term is of use for descriptive 

 purposes, but it is apt to be misleading if it favors the impression that the general 

 sac of the peritoneum is divided into two perfectly distinct parts. 



