1897.] NEW YORK ACADEMY OF SCIENCES. 87 



vein, the nerve sends a large branch (Fig. IV., 12) upward and 

 inward, supplying the integument as far as the median line, and 

 a smaller division downward and inward, in company with the 

 Supra-sternal nerves, supplying the integument over the origin of 

 the Sterno-cleido-mastoid, jugulum, and manubrium sterni (Fig. 

 IV., 13). 



III. Nn. descendentes. 



These form three divisions. Supra-sternal, Supra-clavicular and 

 Supra-acromial and are derived from the Fourth Cervical nerve 

 (Plate VI., Fig. I., 14, 15). 



The general arrangement (Fig. III.) corresponds to the 

 human distribution. The nerves are remarkable for the number 

 and size of the individual branches, and for the extensive area 

 of distribution, the integument of the pectoral region being sup- 

 plied by them to below the level of the nipple. 



The Supra-acromial division sends large branches over the 

 prominence of the shoulder, extending on the lateral aspect to 

 the level of the Deltoid insertion. 



The supra-clavicular nerves send a constant branch to suppl}'^ 

 the integument over the lateral portion of the Pectoralis major, 

 down as far as the level of the great tuberosity, on the lateral 

 and anterior aspect of the shoulder. 



Other branches of this division extend to the lower border of 

 the Pectoralis major, giving offsets to the integument of the 

 axilla and of the antero-internal surface of the arm, as far down 

 as the lower extremity of the bicipital groove. 



The greatest interest attaches to the formation of the deep 

 cervical loop, the communication with the Hypoglossal and the 

 innervation of the muscles connected with the Hyoid bone. 



The general type conforms to the usual arrangement seen in 

 the human subject. 



The significance of the Descendens noni of anthropotomy was 

 pointed out by Bach in 1834, who first referred the nerve to its 

 proper derivation from the cervical plexus. 



Longet and Volkmann came to the same conclusion on physi- 

 ological grounds. 



Later Luschka, E. Bischoff and Holl further determined the 

 derivation of the Descendens noni from the cervical plexus 

 through the communication of the First and Second Cervical 

 nerves with the Hypoglossal. 



The arrangement of the human plexus and of the deep cervi- 

 cal loop is shown in Plate III., Fig. V., taken from Holl's rep- 

 resentation, which indicates sufficiently'^ the usual disposition and 

 derivation of the branches. 



