LUMBAR GANGLIA. 489 



to form a gangliform circle, from which branches pass off in all direc- 

 tions, like rays from a centre. Hence the entire circle has been named 

 the solar plexus. 



The Solar plexus receives the great splanchnic nerves ; part of the 

 lesser splanchnic nerves ; the termination of the right pneumogastric 

 nerve ; some branches from the right phrenic nerve ; and sometimes 

 one or two filaments from the left. It sends numerous filaments 

 which accompany, under the name of plexuses, all the branches given 

 off by the abdominal aorta. Thus, we have derived from the solar 

 plexus the 



Phrenic plexuses, 



Gastric plexus, 



Hepatic plexus, 



Splenic plexus, ' 



Supra-renal plexuses, 



Renal plexuses, 



Superior mesenteric plexus, 



Spermatic plexuses, 



Inferior mesenteric plexus. 



The Renal plexus is formed chiefly by the lesser splanchnic nerve, 

 but receives many filaments from the solar plexus. 



The Spermatic plexus is formed principally by the renal plexus. 



The Inferior mesenteric plexus receives filaments from the aortic 

 plexus. 



LUMBAR GANGLIA. 



The Lumbar ganglia are four in number on each side, of the peculiar 

 pearly grey colour, fusiform, and situated upon the anterior part of the 

 bodies of the lumbar vertebrae. 



The superior and inferior branches of the lumbar ganglia are branches 

 of communication with the ganglion above and below, as in the dorsal 

 region. 



The external branches., two or three in number, communicate with 

 the lumbar nerves. 



The internal brandies consist of two sets ; of which the upper pass 

 inwards in front of the abdominal aorta, and form around that trunk a 

 plexiform interlacement, which constitutes the lumbar aortic plexus ; 

 the lower branches cross the common iliac arteries, and unite over the 

 promontory of the sacrum, to form the hypogastric plexus. 



The Lumbar aortic plexus is formed by branches from the lumbar 

 ganglia, and receives filaments from the solar and superior mesenteric 

 plexuses. It sends filaments to the inferior mesenteric plexus, and ter- 

 minates in the hypogastric plexus. 



The Hypogastric plexus is formed by the termination of the aortic 

 plexus, and by the union of branches from the lower lumbar ganglia. 

 It is situated over the promontory of the sacrum, between the two 



