206 



Study of the Abdominal and Border-Nerves in Man 



on its median margin to the dense tissue surrounding the umbilicus. 

 This occurred in. 73 out of 85 instances. In 13 out of the 85 instances 

 (15.3;^), the transverse tendon corresponding to the 11th rib was inti- 

 mately united to the tissue surrounding the umbilicus. See Fig. V. 

 In 9 of these instances the transverse tendon corresjoonding to the 

 10th rib Avas absent, in 4, present. 



I have discovered no close relation between the development of the 

 7th, 8th, 9th, 10th, and 11th nerves, and the transverse tendons corre- 

 sponding to them on the one hand, and race, sex, side of body, skeletal 

 conditions, position of the lumbo-sacral plexus, or distribution of the 

 border-nerves, upon the other. 



Okigin of the Most Distal Abdominal JSTerve En^tepjxg the 

 Eectus Muscle. See Table III. — As may be seen from the table, the 

 20th spinal (12th thoracic) nerve is the most distal spinal nerve sup- 

 plying the rectus muscle in the great majority of instances (9G out of 

 112 instances, 85.8^). 



The nineteenth spinal nerve was the last nerve to furnish fibres to 

 the rectus muscle in but two instances. In both of these the spinal 

 column was shorter than normal, the plexus had an anterior position, 

 and the border-nerves were of a proximal type.^ 



Frequency with 2i<hicJi the most distal nerve to the rectus ahdominis muscle arose in the 

 types of plexus designated^ from the spinal nerves indicated in the column at the left. 



6 Owing to an unfortunate oversight, a number of the earlier charts, made at a time 

 when especial care was not taken in the study of the abdominal nerves, were included 

 in making up the column on the " last nerve to the rectus muscle" in the Tables 2-8, 

 in the article by Bardeen and Elting, on "A statistical study of the variations in the 

 formation and position of the lumbo-sacral plexus in man." Anatomischer Anzeiger, 

 Vol. XIX, pp. 228-237, 1901. These earlier charts should have been excluded in 

 making up this column. The following table is based upon charts which record with 

 especial exactness the more distal nerves of the abdomen: 



