THE NERVOUS SYSTEM. 



317 



thoracic region. In the sacral region there are no rami 

 communicantes, and the ganglia are irregularly arranged. 

 A median ganglion in the sacral region is known as the 

 ganglion impar. There may be two median ganglia. The 

 sympathetic cords terminate in the tail. 



b? 



FIG. 108. CHIEF PART OF LEFT HALF OF SYMPATHETIC SYSTEM CAUDAD 

 OF THE DIAPHRAGM. Semidiagrammatic. 



bl, Bladder ; ce, cceliac axis ; du, duodenum cut off ; dia, diaphragm ; gr, 

 anterior gastric plexus; g, ganglion; im, inferior mesenteric artery; 

 il, external iliac artery; ng, dorsal branch of vagus (Fig. 103, ax} ; 

 nl, ventral branch of vagus; oe, esophagus cut off; p, superior mesen- 

 teric plexus; plx, inferior mesenteric plexus; px, branches to dorsal 

 gastric plexus ; rn, renal plexus ; sm, superior mesenteric artery ; 

 spn, splanchnic major or greater splanchnic nerve from the sym- 

 pathetic cord ; sg, semilunar ganglion ; spc, sympathetic cord' of left 

 side. 



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