788 THE NERVES. 



b. Lesser splanchnic nerve (Fig. 362, 8;. This branch is composed of 

 two or three filaments that emanate from the last subdorsal ganglia, and 

 which, instead of joining the great splanchnic nerve like the others, with 

 which they communicate by one or two fine divisions, collect in a short thin 

 cord, whose ramifications pass directly into the solar plexus, or are con- 

 founded with the nerves of the kidney and the suprarenal capsule. 



4. Lumbar Portion of the Sympathetic. 



This is a cord similar to that of the dorsal portion, and provided with 

 fusiform ganglionic enlargements equal in number to the pairs of lumbar 

 nerves. This cord is applied against the psoas parvus, near the common 

 inferior vertebral ligament, and is covered on the left by the aorta, on the 

 right by the posterior vena cava. It is directly continued by the sacral 

 portion of the sympathetic chain at the lumbo -sacral articulation. 



AFFERENT BRANCHES. Furnished by the inferior branches of the lum- 

 bar nerves, these ramuscules comport themselves exactly like those of the 

 dorsal region. 



EMERGENT BLANCHES. These are short filaments, analogous to those 

 which, by their union, constitute the splanchnic nerves. Their number is 

 not constant, and is generally less than that of the ganglia. Two or three 

 join the lumbo-aortic plexus; the others gain the origin of the small 

 mesenteric artery, anastomose around it with the posterior extremities of 

 the branches of that plexus, and thus form another single nervous network 

 designated the posterior mesenteric plexus (Fig. 362, 18). 



This plexus, in whose centre is a more or less voluminous ganglion, 

 sends to the various branches of the small mesenteric artery ramifications 

 destined for the walls of the small colon and the rectum. 



It supplies besides : 1. Two or three large branches which follow the 

 posterior mesenteric vein, and join the anterior mesenteric plexus, after 

 giving off some divisions to the tissue of the colic mesentery (Fig. 362, 

 19). 



2. Satellite branches to the two spermatic arteries, constituting the 

 plexus of that name (Fig. 362, 20). 



3. Two or thres long divisions (Fig. 362, 21) which enter on each side 

 of the pelvis by passing beneath the external face of the peritoneum, and 

 reach the lateral plane of the rectum, where they meet the filaments 

 emanating directly from the inferior sacral nerves. From the anastomoses 

 of these divisions results a rich nervous network, called in Man the hypo- 

 gastric plexus, and which we have designated the pelvic plexus ; this net- 

 work is destined to all the organs contained in the pelvic cavity (Fig. 362, 

 23). 



5. Sacral Portion of the Sympathetic. 



A continuation of the lumbar cord, this portion of the sympathetic chain is 

 situated beneath the sacrum, to the inner side of the inferior sacral nerves. 

 It offers four very elongated ganglia, which communicate with these nerves 

 by one or more filaments, and which give rise to several very fine ramus- 

 cules that are lost in the cellular tissue on the inferior face of the sacrum. 



Its posterior extremity, which terminates behind the great sympathetic, 

 does not always comport itself in the same manner. We sometimes see it 

 become attenuated to a very delicate ramuscule, which passes on to the 

 median coccygeal artery, and anastomoses with that of the opposite side. 



