BKACHIAL ARTERIES. 



419 



than the left. Both pass forwards between the layers of the 

 anterior mediastinum, the right below, the left to the side of the 

 trachea, and partly under the oasophagus. 



The following are the arteries given off alike by both brachials. 

 The first four arise within the thorax, the next two at its entrance, 

 while the last two arise externally. 



Dorsal. 



Superior cervical. 

 Vertebral. 

 Internal thoracic. 



External thoracic. 

 Inferior cervical. 

 Prescapular. 

 Subscapular. 



FIG. 



Arteries of the neck exposed on the left side, a, Anterior aorta ; a', Left brachial ; a", Eight 

 brachial, or brachio-cephalic ; 6, Left dorsal ; c c, Superior cervical ; d, Vertebral ; e, Inferior 

 cervical ; /, Cephalic or common carotid ; /", Left, and /", Right carotid ; y g, CEsophageal twigs ; 

 h h, Trachea! twigs ; i i, Muscular twigs ; it, Thyroid ; I, Thyro-lanrngeal ; m, Branch to parotid 

 gland. 



The DORSAL artery runs on the outer side of the trachea, 

 oesophagus, sympathetic nerve, and longus colli muscle, through 

 the second intercostal space, reaching the withers ; it supplies 

 the muscles of that region. The anterior branch goes to the 

 splenius and complexus major, anastomosing with the terminal 

 twigs of the cervical. Within the thorax, the dorsal gives off a 

 few twigs to the mediastinum, and a large subcostal branch 



