THE ASCENDING AORTA 



579 



THE ASCENDING AORTA (AORTA ASCENDENSX- 



The ascending aorta is about two inches (5 to 6 cm.) in length. It commences 

 at the base of the left ventricle, on a level with the lower border of the third costal 

 cartilage, behind the left half of the sternum; it passes obliquely upward, forward, 

 and to the right, as high as the upper border of the second right costal cartilage, 



VAGUS NERVE 



CARDIAC NERVE 

 SUPERIOR INTER- 

 COSTAL VEIN 



CARDIAC NERVE 



LIGAMENTUM 

 ARTERIOSUM 



VENA AZYGOS 

 MINOR 



SYMPATHETIC 

 GANGLION 



GREAT SPLANCHNIC 

 NERVE 



FIG. 431. The thoracic aorta and its relations. (Poirier and Charpy.) 



describing a slight curve in its course, and being situated, when distended, about 

 a quarter of an inch behind the posterior surface of the sternum. At its origin 

 it presents, opposite the segments of the aortic valve, three small dilatations called 

 the sinuses of Valsalva. At the union of the ascending with the transverse part of 

 the aorta the caliber of the vessel is increased, owing to a bulging outward of its 

 right wall. This dilatation is termed the great sinus of the aorta (bulbus aortae). 

 A section of the aorta opposite this part is somewhat oval in outline. The ascend- 

 ing aorta is contained within the pericardium, and, together with the pulmonary 

 artery, is invested in a tube of serous membrane, continued on to them from the 

 surface of the heart. 



Relations. The ascending aorta is largely covered (ventrad) at its commencement by the 

 trunk of the pulmonary artery and the right auricular appendix, and, higher up, is separated 

 from the sternum by the pericardium, the right pleura, and anterior margin of the right lung, 



