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ANATOMY AND PATHOLOGY 
Rt. subclavian a 
Trachea 
Cervicothoracic ganglion 
Sympathetic cardiac br 
Rt. Qzygos vein 
Rt. cranial bronchus 
Cardiac nerves coursing 
to cardiac plexus 
Arch of aorta 
Right pulmonary aa. 
Pulmonary vv. 
Ventral (anterior) vagal trunk 
Bicarotid trunk 
Left subclavian a. 
Ansa subclavia 
Sympathetic cardiac branch 
Recurrent laryngeal n. 
Cardiac branch of vagus n. 
L. cranial lobe of lung 
Vagus n. 
Ventral pulm. plexus 
Tracheobronchial lymph nodes 
L. pulmonary a. 
Left pulmonary a. 
Pulmonary trunk 
Right and left 
principal bronchus 
Esophagus 
Figure 5. — Pulmonary arteries and veins, sheep. 
lung. In man there are usually three bronchial 
arteries, one arising from the right third pos- 
terior intercostal artery and two on the left 
side which arise from the descending thoracic 
aorta. ^ 
HEART 
Sternocostal Surface 
When the ventral portion of the bony thorax 
of the sheep is removed and one looks into the 
pleural cavity, it is evident that the vascular 
and visceral structures passing through the 
cranial thoracic aperature compactly fill this 
narrow space (Figure 10). The superior tho- 
racic aperature of man, as previously noted, is 
much more spacious and has a greater margin 
of safety in the event of encroachment upon 
the thoracic inlet by disease processes or by 
space occupying prostheses (Figure 11). 
The o\'ine heart, within its pericardial sac, 
extends from the second intercostal space to 
the level of the sixth rib. Its apex is directed 
slightly to the right of the median plane and 
the pericardial sac is anchored to the sternum 
by poorly developed fibrous bands, the sterno- 
