APPLIED ANATOMY. 



THE MESENTERY. 



The mesentery extends from the left side of the body of the second lumbar 

 vertebra to the right sacro-iliac joint. It is from 15 to 20 cm. (6 to 8 in.) long at 

 its root and spreads out like a fan, to be attached to the small intestine. It is com- 

 paratively thick, especially toward its root, and contains the superior mescnteric 

 artery and veins, nerves, and lymphatics. The mesenteric lymphatic nodes are 

 numerous, from 130 to 150 (Quain) in number. They are frequently involved in 

 carcinoma and tuberculosis, and may form masses which may be mistaken either for 

 independent tumors or outgrowths from other organs. They are sometimes inflamed, 

 and even cause abscess, being mistaken for appendix disease. They become calcare- 

 ous and by the Rontgen rays may cast shadows which have been mistaken for calculi 

 of the urinary organs. 



The mesentery has its vessels sometimes ruptured by violence or blocked by 

 emboli or thrombi. This is likely to cause gangrene of the intestine to which they 

 are distributed. Jn abdominal operations the greatest care is to be taken not to 



injure these vessels, and in 

 hemorrhage the least possi- 

 ble amount of ligation is to 

 be done. Obstructions of a 

 mesenteric branch may ne- 

 cessitate the resection of that 

 part of the small intestine 

 which it supplies. 



It is particularly im- 

 portant to bear in mind the 

 direction of the mesenteric 

 attachment on account of its 

 influence in directing the 

 course of the blood in cases 

 of hemorrhage. The small 

 intestines are attached at the 

 root of the mesentery like the 

 leaves of a book to its back. 

 Bleeding originating from the 

 right and upper quadrants of 

 the abdomen will pass over 

 the intestines and tend to 

 gravitate toward the right 

 iliac fossa. Bleeding originat- 

 ing from the left and lower 

 quadrants tends to pass under the intestines toward the left iliac fossa. In searching 

 the abdomen through a large median incision for the source of a concealed hemor- 

 rhage, the intestines are first to be pushed down and to the left, and the right side of 

 the abdominal wall lifted with retractors. This will expose to view the upper surface 

 of the small intestines, the ascending and transverse colon, the right kidney, liver, 

 stomach, and head of the pancreas. Should additional search be necessary the small 

 intestines are to be raised and turned upward and to the right (Fig. 422), being 

 brought out of the wound if necessary. This will expose the under side of the small 

 intestines and mesentery, the sigmoid flexure, descending colon, left kidney, spleen, 

 and tail of the pancreas, with the left end of the stomach and left lobe of the liver 

 above. The intestines are never to be turned downward to the right nor upward 

 to the left. 



The mesentery attains its greatest length, according to Treves, from 6 to 1 1 feet 

 below the duodenum, where it measures 25 cm. (10 in.) In hernia the mesentery 

 is lengthened to allow of the descent of the gut. Rarely openings are present in 

 the mesentery which may allow the entrance and strangulation of a coil of the 

 intestine. 



Root of mesentery 



Intersigmoid fossa 

 '(recessus intersigmoideus) 



FIG. 422. The mesentery is seen running downward toward the 

 right sacro-iliac joint; the index finger is below it and the other three 

 fingers above. The small intestines have been raised on the hand and 

 turned upward thus exposing the pelvis and entire left lower half of the 

 abdomen for examination. 



