J270 THE ORGANS OF DIGESTION 



lowed the mesentery down to its root and arranged his loop to be parallel with that root, he then 

 knows that the left and right sides of the intestine face to the left and right sides of the abdomen 

 respectively, and that the end of the loop which points downward is the end nearest the ileo- 

 cecal valve. He can determine the direction of the gut in a similar way in case his finger enters 

 the right fossa. All this would seem very simple were it not for the twists in mesentery and 

 intestine, which tend to mislead one. A little practice will usually enable one to recognize a twist 

 in the mesentery. This should be untwisted by rotation of the gut, after which the direction is 

 determined by another palpation of the mesenteric root." 1 



The studies made of the arrangement and variations of the loops of the mesenteric vessels by 

 Dr. Thomas Dwight 2 have been utilized and expanded by Dr. George H. Monks in laying down 

 rules for the determination of the exact portion of small intestine which may be in the surgeon's 

 hand.* His views are as follows: 



"General Vascularity of the Mesentery near the Bowel. Opposite the upper part of the bowel 

 the mesenteric vessels are distinctly larger than opposite any other part of it. These vessels grow 

 smaller and smaller as we pass downward until the lower third of the gut is reached, where they 

 remain about the same size as far as the ileocecal valve. The arrangement of the mesenteric 

 vessels has some features which intimately concern the subject in hand, and which I shall describe 

 with some detail. Diagrammatically speaking, the main branches of the superior mesenteric 

 artery unite with each other by means of loops, which are called for convenience 'primary loops;' 

 in some parts of the tube, 'secondary loops,' and even, occasionally, 'tertiary loops,' are super- 

 imposed upon these. From these loops little straight vessels the vasa recta already referred to 

 run to the bowel, upon which they ramify, alternating, as a rule, as to the side of the intestine 

 which they supply. The mesenteric veins are arranged in a manner somewhat similar to the 

 arteries. 



" The Loops of the Mesenteric Vessels. Opposite the upper part of the bowel there are only 

 primary loops. Occasionally a secondary loop appears, but it is small and insignificant as com- 

 pared with the primary loops, which are large and quite regular. As we proceed down the 

 bowel, secondary loops become more numerous, larger, and approach nearer to the bowel than 

 the primary loops in the upper part. As a rule, secondary loops become a prominent feature 

 at about the fourth foot. As we continue farther downward, the secondary loops (and, possibly, 

 tertiary loops) become still more numerous and the primary loops smaller, the loops all the time 

 getting nearer and nearer to the gut. Opposite the lower part of the gut the loops generally 

 lose their characteristic appearance, and are represented by a complicated network. 



" The Vasa Recta. Opposite the upper part of the intestine the vasa recta are from three to 

 five centimetres long, when the loop of small intestine to which they run is lifted up so as to put 

 them gently on the stretch. They are straight, large, and regular, and rarely give off branches 

 in the mesentery. In the lower third they are very short, being generally less than 1 cm. in 

 length. Here they are less straight, smaller, less regular, and have frequent branches in the 

 mesentery." 



THE STOMACH (GASTER; VENTRICULUS) (Figs. 958, 994). 



The stomach is one of the principal organs of digestion, and serves as a tem- 

 porary receptacle for food. It is the most dilated part of the alimentary canal, 

 and is situated between the termination of the oesophagus (cardia) and the 

 commencement of the small intestine. 



It lies more or less obliquely or horizontally in the epigastric, umbilical, and left 

 hypochondriac regions of the abdomen, and occupies a recess or chamber called 

 the stomach chamber (Fig. 983). When distended the viscus completely fills the 

 space. When the stomach is empty it lies upon the floor of the chamber, and the 

 portion it has vacated is occupied by the transverse colon, which ascends in front 

 of the stomach and finally gets above it. The anterior and left wall of the stomach 

 chamber is formed by the anterior abdominal wall and Diaphragm. The roof 

 is formed by the under surface of the Diaphragm and the under surface of the left 

 lobe of the liver. The floor is formed by the left suprarenal gland and the summit 

 of the left kidney, the gastric surface of the spleen, the upper surface of the pancreas, 

 the transverse mesocolon, and the colon. 



' Intestinal Localization, by George H. Monks, Annals of 



2 Reports of the Meeting of American Anatomists, 1897. 



3 Annals of Surgery, 1903. 



Surgery, October, 1903. 



