BRACHIAL PLEXUS OF NERVES IN MAN 317 



TypeF 



In type F the lateral fasciculus is formed of branches from the 

 fifth, sixth and seventh cervical nerves and the medial of branches 

 from the eighth cervical and first thoracic nerves (fig. 3). The 

 plexuses of this type are exactly like those of types B and E except 

 that the whole of the fifth cervical nerve does not enter the plexus. 

 There are 12 plexuses of this type or 6.85 per cent of the 175. 

 In one of the plexuses that I have classified as belonging to this 

 type there is a small branch from the fourth cervical nerve to 

 the fifth, in addition to the branch from the fifth to the fourth 

 (fig. 21). This latter branch is larger than the branch from the 

 fourth to the fifth, and I have therefore considered the plexus 

 as belonging to group 3, type F. Types B, E, and F correspond 

 to the type and differ from one another exactly as groups 1, 2 

 and 3 differ, that is, B receives a branch from the fourth and E 

 does not, and in F the fifth cervical sends a branch to the fourth. 



TypeG 



In type G there is a branch from the caudal trunk to the lateral 

 fasciculus (fig. 8), just as there is in type C. Types C and G 

 differ from one another in that in C there is a branch from the 

 fourth cervical entering the plexus and in G there is no such 

 branch but there is a branch from the fifth to the fourth cervical 

 nerve. There is only 1 case of this kind making 0.57 per cent 

 of the 175 plexuses studied. 



SYMMETRY AND ASYMMETRY ON THE TWO SIDES OF THE BODY 



As already pointed out a considerable number of the plexuses 

 of my series were from only one side of the body. There are, 

 however, 63 bodies in which there are satisfactory records for 

 both sides. In 39 of these, or 61.90 per cent of them, the type 

 of plexus is the same on both right and left sides, while in the 

 remaining 24 the type of plexus is asymmetrical. 



In these I have tried to determine if the asymmetry is more 

 frequently found in white or colored, in male or female bodies. 



THE AMERICAN JOURNAL OF ANATOMY, VOL. 23, NO. 2 



