Sheep Heart Key
1. right atrium
2. right ventricle
3. left atrium  
4. left ventricle
5. rigt/left auricles  
6. precava  
7. postcava  
8. pulmonary trunk  
9. aorta  
10. pulmonary veins
11. innominate or brachiocephalic artery  
12. left sublclavian artery
13. ligamentum arteriosum
14. coronary arteries  
15. apex  
16. interventricular septum
17. bicuspid valve  
18. chordae tendineae  
19. papillary muscles  
20. trabeculae carnae  
21. aortic semilunar valve