SACRAL PORTION OF THE SYMPATHETIC SYSTEM. 521 



The LESSER SPLANCHNIC NERVE is formed by filaments from 

 the last two or three dorsal ganglia, which, instead of uniting 

 with the great splanchnic, are sent direct to the solar plexus, and 

 are confounded with the nerves of the kidneys and suprarenal 

 plexus. 



LUMBAR PORTION OF THE SYMPATHETIC SYSTEM. 



The lumbar or abdominal portion of the sympathetic chain is 

 a continuation of the dorsal, and like it, has fusiform ganglia at 

 each lumbar nerve. It rests against the psoas parvus muscle, 

 near the inferior common vertebral ligament, and is covered, on 

 the left, by the aorta, and on the right, by the posterior vena 

 cava. It is directly continuous with the sacral portion at the 

 sacro-lumbar articulation. 



The afferent branches to the lumbar ganglia are furnished by 

 the inferior branches of the lumbar nerves; the emergent branches, 

 analogous to those which form the splanchnic nerves, are not 

 constant in number, but are generally fewer than the ganglia. 

 Two or three of them unite with the lumbo-aortic plexus, and 

 the others, gaining the origin of the posterior mesenteric artery, 

 and communicating with the posterior branches of the lumbo-aortic, 

 form the posterior mesenteric plexus, which contains a ganglion 

 more or less voluminous, in its centre. The ramifications of this 

 plexus accompany the different branches of the posterior mesen- 

 teric artery, to be distributed to the floating colon and rectum ; 

 and two or three large branches join the anterior mesenteric 

 plexus, after sending a few small divisions to the colic mesentery. 

 Branches from it also surround and accompany the spermatic 

 arteries, constituting the spermatic plexus ; and lastly, two other 

 long divisions enter the pelvis on each side, and being distributed 

 over the external surface of the peritoneum, gain the side of the 

 rectum, where they meet filaments which emanate directly from 

 the sacral nerves. The communication of these divisions results 

 in a rich nervous network, the pelvic or hypo-gastric plexus, 

 which supplies the organs contained within the pelvis. 



SACRAL PORTION OF THE SYMPATHETIC SYSTEM. 



The sacral or pelvic portion of the sympathetic is the continua- 

 tion of the lumbar, and is situated under the sacrum, and to the 

 inner side of the sacral nerves. It presents four ganglia, which 



