LUMBAR GANGLIA. 441 



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

 roots of each of the spinal nerves. 



The internal branches of the five upper ganglia are pulmonary to join 

 the pulmonary plexuses ; cesophageal to the oesophageal plexus and aortic 

 to the thoracic aorta and its branches ; the first thoracic ganglion more- 

 over sends branches to the cardiac plexuses. The branches of the lower 

 ganglia are aortic, and several large cords, which unite to form the two 

 splanchnic nerves. 



The Great splanchnic nerve arises from the sixth dorsal ganglion, and 

 receives branches from the seventh, eighth, ninth, and tenth, which aug- 

 ment it to a nerve of considerable size. It descends in front of the verte- 

 bral column, within the posterior mediastinum, pierces the diaphragm 

 immediately to the outer side of each crus, and terminates in the semilunar 

 ganglion. 



The Lesser splanchnic nerve (renal) is formed by filaments from the 

 tenth, eleventh, and sometimes from the twelfth dorsal ganglion. It 

 pierces the diaphragm, and descends to join the renal plexus. 



The Semilunar ganglion is a large, irregular, gangliform body, pierced 

 by numerous openings, and appearing like the aggregation of a number 

 of smaller ganglia, having spaces between them. It is situated by the 

 side of the coelic axis, and communicates with the ganglion of the oppo- 

 site side, both above and below that trunk, so as to form a gangliform 

 circle, from which branches pass off in all directions, 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 fila- 

 ments 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, Renal plexuses, 



Gastric plexus, Superior mesenteric plexus, 



Hepatic plexus, Spermatic plexuses, 



Splenic plexus, Inferior mesenteric plexus. 



Supra-renal plexuses, 



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

 receives many filaments from the solar plexus. 



The Spermatic plexus is forme'd 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 vertebra?. 



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 branches consist of two sets ; of which the upper pass in 

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



