THE ABDOMEN 859 



or retro-femoral gland of the outer chain of the external iliac gland'i, 

 by means of one or two vessels which traverse the inguinal canal. 



Bulbar and Memtranous Portions. — The lyinphatics of these portions pass 

 to (i) the internal iliac glands, and {2) the inner chain of the external iliac glands. 



Prostatic Portion. — The lymphatics of this portion join those of the sub- 

 stance of the prostate gland, and pass to (i) the middle chain of the external 

 iliac glands, (2) the internal iliac glands, (3) the lateral sacral glands, and (4) the 

 inner group of the common iliac glands. 



Pelvic Colon. — The pelvic colon succeeds to the iliac colon. It 

 commences at the inner border of the left psoas magnus, just 

 anterior to the left sacro-iliac articulation, and terminates in front 

 of the third sacral vertebra, where it becomes continuous with 

 the rectum. It measures on an average about 15 inches in length, 

 and usually lies in the pelvic cavity over the upper part of the 

 posterior wall, where it rests below upon the bladder and rectum, 

 and may descend on either side of these viscera. It is . sur- 

 rounded by peritoneum, which forms behind it an expanded wavy 

 mesentery, called the pelvic meso-colon, which contains between 

 its two layers the lower two sigmoid and superior hemorrhoidal 

 arteries, with the corresponding veins. The root of this mesen- 

 tery is composed of two limbs, which become continuous at an 

 acute angle. One limb takes an upward course along the inner 

 border of the psoas magnus, and the other passes downwards over 

 the sacral promontory to be attached to the anterior surfaces of 

 the first three sacral vertebrae. At its extremities, which are near 

 each other, the mesentery is short, and the extremities of the 

 pelvic colon are necessarily fixed. The intervening portion, how- 

 ever, is long, and so allows of considerable mobility on the part of 

 the greater portion of the attached gut. A very common course for 

 the pelvic colon to take is to pass to the right wall of the pehds, 

 where it bends and crosses to the left wall, and then bending again 

 it passes to the right as far as the middle line. In such cases, 

 therefore, it describes the letter S. A portion of it is sometimes 

 met with in the abdominal cavity. 



Structure. — ^The chief difference in the structure of the pelvic 

 colon, as compared with the other divisions of the colon, affects 

 the arrangement of the longitudinal muscular fibres. Though 

 arranged at first in three taeniae, these gradually become disposed 

 as two broad taeniae, anterior and posterior. When this has 

 taken place, the longitudinal fibres almost surround the gut, 

 except along the sides, in which situations the usual sacculations 

 are formed. Appendices epiploicae are met with over the pelvic 

 colon. 



Blood-supply. — ^The pelvic colon receives its arteries from the lower 

 two sigmoid arteries, which are branches of the inferior mesenteric. 

 The veins pass to the inferior mesenteric vein, and ultimately into 

 the vena portae. 



The lymphatics pass to the left lumbar lymphatic trunk. 



The nerves are derived from the inferior mesenteric sympathetic 

 plexus. 



