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in the fifth lumbar vertebra which tend to make it approach the sacral 

 type. This simple variation is very frequent. It is called type d in 

 the tables and was found in seventeen out of fifty-two bodies. The 

 shortening of the vertebral column may be further shown by the 

 reduction of the sacral vertebrae to four in number, type c (one body) ; 

 or of the lumbar to four in number, type b (two bodies); or of the 

 thoracic (rib-bearing vertebrae) to eleven in number, type a (three 

 bodies). On the other hand the vertebral column may be lengthened 

 by the addition of a sacral vertebra, type f (one body) ; or of a lumbar 

 vertebra, type g (three bodies) ; or of a thoracic (rib-bearing vertebra) 

 type h (two bodies). These skeletal variations are treated at greater 

 length in a separate article (Anat. Anzeiger, Bd. 18, 1900, p. 377), 



The correspondence between the position of the lumbo-sacral 

 plexus and the condition of the vertebral column is well marked (see 

 tables 2—8 unter "c"). Thus in twelve of the thirteen instances of 

 the type b position of the lumbo-sacral plexus the vertebral column 

 showed marked evidences of reduction. In only one instance was the 

 vertebral column "normal". Thus too in the type C position of the 

 lumbo-sacral plexus the vertebral column was "normal" in only seven 

 out of the thirty-one instances examined. 



On the other hand the skeleton was "normal" in twenty-one out 

 of thirty instances of type D plexus. In three out of nine instances 

 of type E plexus and in two out of eleven instances of type F plexus 

 the vertebrae in some part of the vertebral column were increased in 

 number and this was the case with seven out of the ten instances of 

 type G plexus. 



A study of table 9 will also show this relation of the position 

 of the plexus to the condition of the vertebral column. 



Theoretically it may be assumed that the relation of the spinal 

 nerves to the nerves of the limb is due largely to the position of the 

 latter relative to the axis of the body. When the limb is situated 

 relatively nearer the head a more anterior group of spinal nerves 

 combine to form the nerves of the limb than when the limb is more 

 distally placed. It is interesting to note that an advance of the limb 

 in the proximal direction seems usually accompanied by marked 

 changes in the axial skeleton. And this also is often the case when 

 the limb is more distally placed than "normal". 



The Relation of the "Border Nerves" to the Main Nerves 



of the Limb. 

 In a study of the lumbo-sacral plexus, one has always to take 

 into account those nerves which supply the regions of the body which 



