296 



HUMAN EMBRYOLOGY AND MORPHOLOGY. 



that each nerve may contain functional elements derived from 

 several segments. Each muscle, it must be remembered, is 

 supplied from two, three or more segments of the cord. 



Only three anomalous points in the arrangement of nerves in 

 the upper limb require attention : (1) The segments which 

 supply nerves for the arm are nearly constant. The extent to 



impost root gangl. 



cresi of ilium 



D.11 

 D.12 



Fig. 241.— Plexor Aspect of the Lower Limb showing the Sensory Distribution of the 

 Segmental or Spinal nerves. 



which the 4th cervical and 3rd dorsal contribute varies ; the 

 degree of variation is markedly less than in the lower limb. 

 (2) A part of the musculocutaneous nerve frequently joins the 



