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descriptive terms applicable to the course of the nerves in the limb 

 as we have done above. 



The main nerve trunks which enter the posterior limb are fairly 

 constant in position and in the relation which they bear to the 

 structures of the limb. It has been pointed out above that in the 

 limb there are four main territories, an antero-lateral, an antero-median, 

 a postero-lateral and a postero-median, each of which is supplied by 

 a special nerve trunk. The branches distributed to the various 

 structures in these regions are much less constant in position than 

 are the main nerve trunks. The more the periphery of a given region 

 is approached, the greater is the variety on the course and distribution 

 of the nerves supplying it. There is no fixed boundary line between 

 the different regions. The cutaneous areas and to much less extent 

 the muscular areas tend to overlap and to vary reciprocally in extent. 

 In the present paper, however, no account is taken of the variations 

 in peripheral distribution of the main nerves of the limb. Our present 

 purpose is to point out the frequency with which certain groups of 

 spinal nerves have been found to contribute to those nerves which 

 supply the four main territories of the posterior limb. 



Part I. 



a) The frequency with which given numbers of spinal 

 nerves contributed to the formation of the main 

 nerves of the limb in 246 instances (Table la). 



b) The relation of thisfrequencytothetypeofplexus 

 (Table lb) and 



c) to race, sex and side of body (Table Ic). 



In considering the relation of the spinal nerves to the main 

 nerves of the limb, one of the most important topics is that of the 

 number of spinal nerves which contribute to the nerves of the limb. 

 The conditions which we found in 246 plexuses are recorded in detail 

 in Table 1. We wish here merely to call attention to some of the 

 more striking features revealed in this table. 



The number of spinal nerves contributing to the nerves of the 

 limb varied from six to nine (see Table la). In over 907o of the 

 plexuses, however, seven or eight spinal nerves contributed, seven in 

 26,8 o/° and eight in 65,4 7o of the total number of plexuses examined. 

 In 33,6% of the total number of instances the most anterior nerve 

 contributing to the limb nerves conveyed fibres to the lateral cutaneous 

 nerve alone of the true nerves of the limb; 2% where seven nerves 



Anat. Anz. XIX. Aufsätze. 9 



