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Bardeen, Variatiojis in the LuDibar Plexus. 195 



On Variations in the Distribution of the Spinal Nerves 

 Entering the Lumbar Plexus. 



By C. R. Bardeen, 



The Johns Hopkins University, Baltimore. 



Special attention has been given during the last two or 

 three years in the Anatomical Department of the Johns Hop- 

 kins University to the origin and distribution of the main nerve 

 trunks in the human body. The students in practical anatomy 

 have been encouraged to note carefully any variations from the 

 usual descriptions of the courses of the various nerves and to 

 record the results of their observations on printed " tabulation 

 charts " furnished them. Besides the filling in of the printed 

 charts, diagrammatic drawings have been freely made as a fur- 

 ther means of illustration. The work has been verified and the 

 charts have been carefully controlled by Dr. A. W. Elting dur- 

 ing the early part of the undertaking, during the sessions of 

 1 896- 1 897, and by myself during the past year. 



In these records sex, color, apparent age, and marked 

 peculiarities of bodily structure have been carefully noted as 

 well as the distribution of the larger nerves. It is hoped that 

 from these charts interesting and valuable statistics relating to 

 the distribution of the peripheral nerves may be obtained. 

 There is a very great variety in the modes of origin and distri- 

 bution of the peripheral nerve trunks in certain regions of the 

 body. This is well illustrated by the conditions found in the 

 nerves entering into and leaving the lumbar plexus. To a con- 

 sideration of these nerves I invite your attention today. 



In man the lumbar plexus is formed as follows : 



The eleventh thoracic nerve has in the main the character- 

 istics of a typical segmental nerve. It divides into a dorsal 

 primary division for the supply of the skin and muscles of the 

 back and a primary ventral division for the supply of the ven- 

 tro-lateral musculature and skin, and gives off a visceral branch, 



