1276 



THE ORGANS OF DIGESTION 



the fundus and pass over into larger and larger rings to encircle the entire organ. At the pylorus 

 they are most abundant, and are aggregated into a circular ring or Sphincter, which projects into 

 the cavity, and forms, with the fold of mucous membrane covering its surface, the pyloric valve 

 (Fig. 997). The circular fibre stratum is continuous with the circular layer of the oesophagus, 

 the fibres being interlaced at the transition. 



The oblique fibres (fibrae obliquae] arise at the left side of the cardia from the circular fibres 

 of the oesophagus. The fibres pass down in the anterior and posterior walls, and almost reach 

 the pylorus. Certain oblique muscular fibres encircle the fundus of the stomach in a series of 

 rings. 



The submucous coat (tela submucosa) consists of loose areolar tissue, connecting the mucous 

 and muscular coats. It supports the large bloodvessels previous to their distribution to the 

 mucous membrane; hence it is sometimes called the vascular coat. 



Themucous membrane (tunica mucosa) (Figs. 1000, 1001, and 1002) is thick, its surface smooth, 

 soft, and velvety. In the fresh state it is of a pinkish tinge at the pyloric end, and of a red or 

 reddish-brown color over the rest of the surface. In infancy it is of a brighter hue, the vascular 



FIG. 999. The middle and deep muscular layer of the stomach, viewed from above and in front, (gpalteholz.) 



redness being more marked. It is thin at the cardiac extremity, but thicker toward the pylorus. 

 During the contracted state of the organ it is thrown into numerous folds or rugae (plicae mucosae) 

 (Figs. 1000 and 1002, A), which for the most part have a longitudinal direction, and are most 

 marked toward the pyloric end of the stomach and along the greater curvature. These folds 

 consist of mucous and submucous coats, and are entirely obliterated when the organ becomes 

 fully distended. 



Structure of the Mucous Membrane. When examined with a lens the inner surface of the 

 mucous membrane presents a peculiar honeycomb appearance, from being covered with small 

 shallow depressions, the gastric crypts or pits (foveolae gastricae) (Figs. 1001 and 1002, B) of a 

 polygonal or hexagonal form, which vary from ^ to ^ of an inch in diameter, and are sepa- 

 rated by slightly elevated ridges (plicae villosae). The pits in the cardiac and fundal portions of 

 the stomach extend through about one-sixth the thickness of the mucosa, while in the pyloric end 

 they extend through about one-half the mucous coat. In the bottom of the crypts are seen 

 three to seven orifices of minute tubes, the gastric glands (Fig. 1002, B), which are placed per- 



