THE PULMONARY ARTERY. 751 
pulmonary vein ; Jehind it, is the left bronchus ; above, the aortic arch, to which it is con- 
nected by the ligamentum arteriosum, and the left recurrent laryngeal nerve ; below, it 
is in relation with the lower left pulmonary vein. After entering the lung it descends, 
like the right pulmonary artery, behind and on the outer side of the stem bronchus, 
and between its ventral and dorsal branches. 
Branches.—Just before passing through the hilus it gives off a branch to the 
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re 
Fic. 552.—THE PULMONARY ARTERIES AND VEINS AND THEIR RELATIONS. 
Parts of the ascending aorta and superior vena cava have been removed. 
1. Aorta. 11. Internalmammary artery. 22. Sterno-hyoid muscle. 33. Subclavius muscle, 
2. Superior vena cava. 12. Subclavian vein. 23. Platysma. 34. Ist rib. 
8. Upper right pulmonary 13. Suprascapular artery. 24, Sterno-hyoid muscle. 35. Left common carotid 
vein. 14. Transversecervicalartery. 25. Sterno-thyroid muscle. artery. 
4, Right pulmonary artery. 15. Vertebral artery. 26. Sterno-mastoid muscle. 36. Aorta. 
5. Superior vena cava. 16. Inferior thyroid artery. 27. Phrenic nerve. 37. Ligamentum arteriosum. 
6. Left innominate vein. 17. Internal jugular vein. 28. Vagus nerve. 38. Left pulmonary artery. 
is Innominate artery. 18. Common carotid artery. 29. Vertebral artery. 39. Upper left pulmonary 
8. Right innominate vein. 19. Superior thyroid artery. 30. Inferior thyroid artery. vein. 
9. Subclavius muscle. 20. Sterno-thyroid muscle. 31. Thoracic duct. 40. Pulmonary artery. 
10. Clavicle. 21, Omo-hyoid muscle. 32. Left subclavian artery. 
upper lobe, and in the substance of the lung its branches correspond with the ventral, 
dorsal, and accessory branches of the bronchial tube. 
