ABDOMEN. 269 



of attempting t<> teach the physiology of reflexes, but simply to impress on the 



student the imperative necessity of being able, in dissection, to show the place 



where somatic and sympathetic nerves communicate, by the ncrri fffmrnvtUtOXtes. 



/s there any liiffcrcncc in tlic trattsmissioHol />>'. 'iiintic and sympathetic 



From the decided difference in the character of pain reported by these two 

 nerves we would conclude there is a difference. 



\\'li<it /'.< tlic ditfereiict in traMsmissional powtr ? 



This is conjectural only. Simply to aid the memory, we might view the 

 subject in the light of logical reasoning. For physiological facts, however, you 

 must consult physiologists. Structure is the correlative of function ; hence, 

 m irked differences in function entail consequent marked differences in structure. 



Rrnal Ptfxus r , 



_ _____ _ v ___ _ Kidney 



Renal Colic 



-X Ureter, Bladder, Lumtar and Penis reflex *rta 



Cardiac Plexus 

 X X /fear! 



-X Arm, finyen. Shoulder andAtdomina 



Cardiac Plexus . 



~ Pnrnmonta 



1 Pain in Lumbar reaion 

 2 Pain in tht fyigasfrum 

 ' .7 Pain o/i the sound aide 



Mm Plexus ^^, Cr,-anlis 

 X ^ Salftnyitii 



\ > ^ 1fH9m9 



Extremities - The rff/fx firt.as frequently 



., ^ Gastric Ptexus 



f % y Stomach 



and Confer 



X Atdominal Walla, The reflex area 



I! pogas/ric Ptexus 



v . Mesttne 



* X f'nt*mi 



-^Kijht Iliac rtvion andVmliliats. Toe rt/Tex ana 



Kit:. 186. SHOWINC SCHEMATICALLY A SENSORY REFLEX CIRCUIT. 



The converse is true. The sympathetic individual fibre is smaller ; its fibres 

 undergo numerous interruptions, not only in the ganglia of the gangliated cord, 

 but also in numerous other plexuses, of which the plexuses of Auerbach and 

 Meissner may be taken as the type. 



Somatic and sympathetic nerves are routes by which nerve-impressions travel. 

 Nerve-impulses, of whatever kind, are, then, projectiles, and amenable to the law 

 of. projectiles : " Projectiles follow the line of greatest traction, the point of 

 least resistance, or the resultant of the two." If, then, the small calibre of 

 sympathetic nerves, and their frequent interruptions, form a resistance to nerve- 

 impulses, then somatic nerves, possessing neither of these assumed impedi- 

 ments, logically furnish lines of least resistance. 



Our conclusion would be, then, that in the case of a given irritation in a sym- 

 pathetic area, as in cardiac valvular lesion, the sympathetic reports the pain to 



