Practicum IV. The Cat's Heart. 23 



a. Recognize the LEFT AURICLE and VENTRICLE and the AORTA with 

 its ARCH. 



b. Note the two great BRANCHES from the aortic arch : 



i The smaller, farther from the heart, is the LEFT STJBCLAVIAN, car- 

 rying blood to the left arm. 



2. The larger the BRACHIOCEPHALIC, supplies the head and right 

 arm, whence its name. 



c. Note the larger branches of the brachiocephalic ; commonly the 

 first is the LEFT CAROTID carrying blood to that side of the head ; then 

 the remainder divides into the RIGHT CAROTID and the RIGHT SUBCLAV- 

 IAN, this latter being continued as the AXILLARY seen in PI. IV. 



d. Sometimes the right subclavian arises as the first branch of the brachiocephalic 

 and the remainder bifurcates into the two carotids ; Anatomical Technology, Fig. 4. 



<?. The Pulmonary Vessels. Although these are cut short the PUL- 

 MONARY VEINS may be traced to the left auricle, most easily by blowing, 

 while the ARTERY passes under (caudad of) the aorta to the right ven- 

 tricle. 



f. Make an enlarged diagram of the heart and its vessels, indicating 

 especially the branches of the aortic arch as described above. Compare 

 with the condition in man in various mammals ; see Owen's Comparative 

 Anatomy, III, Fig. 419. . 



