THE INTESTINES. 411 



begins at the caecum, and terminates by suddenly contracting at the origin 

 of the small colon. 



Length Capacity. It is from about 10 to 13 feet in length, and has a 

 medium capacity equal to 18 gallons. 



Form General disposition. Eemoved from the abdominal cavity, and 

 extended on a table or on the ground, this portion of the intestine appears as 

 a voluminous canal, offering a succession of dilatations and contractions ; 

 its surface being traversed by longitudinal bands, and sacculated and 

 furrowed transversely for a great part of its extent, exactly like the caecum. 

 It is also doubled in such a manner as to form a loop, whose two branches 

 are of equal length and are held together by the peritoneum, which is 

 carried from one to the other ; so that the terminal extremity of the large 

 colon returns towards the point of its origin. 



But this colic flexure, owing to its length, could not be contained in the 

 abdomen ; and it is therefore doubled in its turn from above to below and 

 from right to left (at the points P, F, in Fig. 20 ) ^ 2Q7 



and forms curvatures which will be noticed pre- 

 sently. From this circumstance, it happens that 

 the large colon, studied in the abdominal cavity, 

 is divided into four portions lying beside each 

 other in pairs ; so that a transverse section of that 

 cavity, made in front of the base of the caecum, 

 would give for this intestine the results indicated 

 in the annexed figure. 



Course and Helations. In following the course 

 of the large colon from its origin to its termina- 

 tion, in order to study its fou r< portions in their pLAN Qp TRE 

 normal relations, the following is observed : 



Commencing from the arch of the caecum, the colon is directed forwards, 

 above the middle portion of that reservoir, which it follows to its point. 

 Arrived at the posterior face of the diaphragm at its most declivitous part, 

 it bends downwards and to the left, forming its first or suprasternal flexure, 

 because it rests on the xiphoid cartilage of the sternum (Fig. 204, g~). Here 

 begins the second portion of the viscus, which is in immediate contact 

 with the inferior abdominal wall, and extends backwards into the pelvic 

 cavity, where it is inflected to the left to constitute the pelvic flexure. This 

 curvature, the centre of the colic loop, responds to the rectum and bladder, 

 as well as to the deferent canals, or the uterus and ovaries, according to 

 the sex. It is succeeded by the third portion of the colon, which is carried 

 forward, above, and to the left of the preceding. Bound to the second 

 division by peritoneum and connective tissue, this new section reaches the 

 phrenic centre, and is then doubled upwards and to the right. The flexure 

 arising from this third duplicature is called the diaphragmatic, because of its 

 relations with the musculo-aponeurotic membrane which partitions the great 

 cavity of the trunk, or the gastro-Jiepatic curvature, in consequence of its lying 

 equally against the liver and stomach (it is also designated the sigmoid flexure) 

 (Fig. 204, &). To this flexure succeeds the fourth and last portion of the 

 large colon, bound to the first portion, as the second is to the third. This 

 extends, posteriorly, to the base of the caecum, where it terminates in a 

 sudden contraction, and is continued by the small colon ; it occupies the 

 sublumbar region, and through the medium of a cellular layer is applied 

 against the inferior face of the pancreas and the inner side of the caecal arch. 



Mode of attachment. The large colon can be easily displaced in the 



