SPLANCHNOLOGY. 199 



creatic duct commences at the small end, and extends to tlie large, receiving 

 numerous branches on each side. It generally joins the ductus choledochus 

 in a small dilatation just before the duodenal opening ; a second duct some- 

 times opens directly into the duodenum. An accessory gland, called the 

 lesser ixmcreas^ is sometimes found attached to the head of the pancreas. 

 The pancreatic juice is mixed with the biliary in the duodenum, to separate 

 chyle from the chyme of the food. Its especial office, from recent investi- 

 gations, appears to lie in the assimilation of fats. 



9. The Peritoneum, The peritonaeum is the largest serous membrane 

 in the body, investing the viscera of the abdomen, much as those of the 

 thorax are embraced by the pleura. The peritonteum is a closed sac, and 

 when opened, presents a continuous surface, which may be traced through- 

 out the whole extent without interruption. The different folds which the 

 peritoni^um forms in its course are mainly the lesser omentum, the great 

 omentum, the splenic omentum, the colic omentum, the appendices epi- 

 ploic«, the mesenter}^, meso-coecam, and meso-rectum. The relations of 

 the peritomeum in the different parts of its course will be best understood 

 by reference to 2^1. 130, fig. 9. 



Proceeding from the umbilicus, \ the peritonaeum passes along the inside 

 of the anterior abdominal wall, ^ ; then bending backwards, it lines the 

 inferior surface of the diaphragm, ^, forming on it the suspensory ligament, 

 *, of the liver, ^ ; it passes below the diaphragm over the liver, and coats 

 its upper surface, ", the gall bladder, ', and a portion of the lower surface 

 of the liver. From the liver it passes to the stomach, and forms, ^, the 

 anterior lamina of the lesser or gastro-hepatic omentum, and passes from 

 the stomach to the spleen as the anterior lamina of the gastro-splenic liga- 

 ment. The peritonaeum next bends back on itself from the diaphragm in 

 the form of a sac {saccus cpiploicus), the opening, '", to which is known as 

 the foramen of Winslow. The two lamince of the gastro-hepatic omentum 

 separate at the lesser arch of the stomach, '\ to inclose this organ, the 

 posterior layer giving a serous covering to its back part, and the anterior to 

 its fore part ; they then touch each other again, ''\ along the great arch pf 

 the stomach, and being joined by the peritonaeum from the spleen and the 

 splenic vessels, descend to the lower part of the abdomen under the name 

 of the gastro-colic or the great omentum, ". This then turns on itself 

 and ascends obliquely backwards to the arch of the colon, along the convex 

 edge of which its lamina? separate to inclose this intestine, ", and its 

 vessels. Along the concave edge of the colon these laminae again unite, 

 ", to form the transverse meso-colon which passes backwards to the spine. 

 Opposite the duodenum, ", this process separates into an ascending and 

 descending layer, between which the inferior division of the duodenum 

 lies. The ascending layer covers the pancreas, *', and proceeding to the 

 back part of the right lobe of the liver, becomes continuous with the peri- 

 tonoeal layer, ", of this viscus. The descending layer, '", of the transverse 

 meso-colon expands in each lumbar region, in which it attaches the lumbar 

 portion of the colon by a duplicature called the right and left lumbar meso- 

 colon ; it is thence reflected forwards over the small intestines, ""• ", and 



906 



