DISSECTION OP THE DOG 3 



The origin of the muscle is from the sternum from the level of the second 

 costal cartilage to the xiphoid process. Its insertion is into the medial tubercle 

 (tuberculum minus) of the humerus, and, by means of a thin tendon which 

 crosses the origin of the biceps, to the lateral tubercle (tuberculum majus) 



-P. jugularis externa 



m. brachio-cephalicus 

 ., — m. sterna -cephalicus 



-m. pectoralis superficialis 



n. medianus 



m. biceps brachii 



ft. ulnaris 

 m. triceps brachii 

 m. tensor fasciae antibrachii 



x m. pecloralis profundus 



-m. rectus abdominis 



Fig. 1. — Dissection of the pectoral region. 



also. The most caudal fibres of the muscle are connected with the cutaneous 

 muscle of the abdomen. 



At the root of the neck is a triangular space of some moment on account 

 of the structures contained therein. The lateral limit of the space is formed 

 by the brachio-cephalic muscle. Medially the sterno-cephalic muscle forms 

 its boundary ; while its base — caudal in position — lies at the edge of the 

 pectoral muscles. 



B 2 



