424 



Mr. W. P. Herringham. 



the nerve until it has descended to the third or lowest part of the 

 muscle. The connective tissue which in the adult binds all the nerve 

 together has not in the foetus jet grown up, and the system of the 

 nerve is naturally exposed. The supply of each nerve is variable. If 

 the 5th root is large it will send on fibres to supply with the 6th the 

 middle of the muscle. If it is small it spends itself entirely on the 

 upper part, but however the different roots may vary in size I have 

 never in the numerous dissections I have made seen them alter their 

 relative positions. 



Two typical examples from adults may be quoted. In one, the 5th 

 gave twigs to the first three digitations, and then a small fibre to the 

 6th. There was no root from the 7th. In the other, the 5th supplied 

 the first two, the 6th alone supplied the next two, and the 6th and 7th 

 the remaining digitations. In these there was no splitting of the 

 nerve necessary. The drawings shown were made from them. 



Diagrammatic Sketch of Posterior Thoracic from two Adults. 



m H 



VSmm Ei9 



















































V, VI, VII = Branches from 5th, 6th, and 7th roots. 



1, 2, 3 = First, second, and third parts of serratus magnus. 



As the 5th leaves the scaleni it receives a communicating branch 

 from the 4th, which therefore does not enter the rhomboid branch, or 

 the posterior thoracic. The communicating branch varies consider- 

 ably in size. I have at times been scarcely able to recognise the twig, 

 at others it is a sixteenth of an inch thick. In the remainder of the 

 paper this branch is not separated from the 5th. 



Soon after this the 5th root joins with the 6th. It is usually at 

 their junction that the suprascapular nerve is given off, but it is not 



