1030 



THE ORGANS OF DIGESTION. 



The nerves which supply the caecum, ascending and right half of the trans- 

 verse colon are sympathetic, coming from the superior mesenteric plexus derived 

 from the coeliac plexus. Those which supply the left half of the transverse colon, 

 the descending and sigmoid colon come from the inferior mesenteric plexus 

 derived from the aortic plexus. In their course they accompany the arteries. 



The caecum (ccecus, blind) (Fig. 653) is the head of the colon, or that part of 

 the large intestine situated below the ileo-caecal valve, some say below the ileurn. 

 Its length and breadth are never equal, the breadth being always the greater. 

 The opinions vary thus 



Average length. Average breadth. 



Quain 2J inches 3 inches 



Berry 6 cm. 7 cm. 



Treves 6 " 8 " 



Struthers 6 " 6 " 



Luschka 4-12 " 



Sappey 8-10 " 



Henle" 5.5" 



The discrepancies are due largely to methods of measurement. Treves takes 

 as the upper limit of the caecum the lower edge of the ileum. Berry states this 

 is too short, and the upper limit of caecum is on the level of the ileo-caecal valve, 

 or Struthers' " fraenal furrows," which are continuations of the ileo-caecal valve. 

 If these furrows cannot be seen externally, take as the upper limit an " approxi- 

 mation line," drawn transversely across the colon from a point midway between 

 the upper and lower edges of the ileum. In 100 cases this gave Berry's figures, 

 6 and 7 cm., for average length and breadth. " Sex has no influence upos size, 

 but it varies with age, being absolutely and relatively larger in the adult. Caeca 

 of insane persons are apt to be abnormal " (Berry). 



The caecum lies in the right iliac fossa above the outer half of Poupart's 

 ligament, its point being at about the middle, immediately behind the anterior 



FIG. 651. A. Caecum of Mangabey monkey. B. Caecum of spider monkey. (Treves.) 



abdominal wall in front of the ilio-psoas muscle (Fig. 578). Should it be long 

 it may extend more or less into the pelvic cavity (Fig. 626). 



Many statements are made as to its peritoneal relations. Bardeleben first 

 stated it was wholly invested by peritoneum ; Luschka, Treves, very positively, 

 Struthers and Jonnesco all agree. Quain states that in 5 per cent, of cases the 



