2Q2 LILY C. SHUDDEMAGEN. 



pair by pair, from between the caudal vertebrae and supply the 

 muscles of the tail. 



The most anterior division of the spinal nerves is the cervical 

 (PI. XXVI., C. i-C. 8\ Of these there are eight pairs. 



Of the thoracic nerves (PI. XXVI., T. i-T. 10] there are ten 

 pairs. 



The lumbar region is very short, containing six pairs of nerves 

 (PI. XXVI., L. i-L. 6}. 



The sacral nerves (PI. XXVI., 5. i-S. 8} are eight in number. 



The exact number of the caudal nerves was not ascertained 

 by me. But they are quite numerous, possibly as many as 

 fifteen to twenty pairs. 



(a) Cervical Plc.vus.- -The cervical plexus (PI. XXVI., C. 

 iC. 8} is composed of the dorsal branches of the eight pairs of 

 cervical nerves. These branches pass almost vertically upwards, 

 interlace, and supply the dorsal neck muscles. On PI. XXVI., 

 on the right hand side of the drawing, are shown the dorsal 

 branches of the cervical nerves. 



(/>) Brachial Plexus. - -The brachial plexus is composed of the 

 large ventral branches of the third, fourth, fifth, sixth, seventh, 

 and eighth cervical nerves, and the first and second thoracic 

 nerves. The formation of the plexus is due to the union of the 

 several nerves, by means of strong connecting branches. The 

 plexus lies in the axilla, and all the component nerves pass out 

 laterally, almost parallel to the first rib. By means of its 

 branches, the arm and shoulder are innervated. 



The three subscapular nerves, the cranial (PI. XXVI., Sub. Sc. 

 /), the middle (PI. XXVI., Sub. Sc. 2), and the caudal (PI. 

 XXVI., Sub. Sc. j), all supply muscles on the ventral surface of 

 the scapula. The cranial subscapular nerve (PI. XXVI., Sub. 

 Sc. /) arises from the third, fourth, and fifth cervical nerves. 

 The middle subscapular nerve (PI. XXVI., Sub. Sc. 2) arises 

 from the sixth cervical nerve. The caudal subscapular nerve 

 (PI. XXVI., Sub. Sc. 3} arises from the sixth, seventh, and eighth 

 cervical nerves. 



The suprascapular nerve (1. XXVI., Sup. Sc.) arises from the 

 fifth cervical nerve. It passes onto the dorsal side of the scapula 

 and enervates the supraspinatus and infraspinatus muscles. 



