2io APPLIED ANATOMY. 



or the whole of the septa between the atria and ventricles; to a patulous condition of 

 the foramen ovale of the right atrium ; and also to a persistent patulous condition of 

 the ductus arteriosus. Children so affected, if they outlive infancy, usually die before 

 reaching adult age. 



Aneurism. This portion of the aorta is also a favorite seat of aneurism. The 

 symptoms produced will depend of course on the direction which the tumor takes. 

 If it tends anteriorly it would involve the lungs and pleurae and the phrenic and vagus 

 nerves, also the sympathetic. The displacement of the left lung would be the more 

 marked. Involvement of the recurrent laryngeat nerve might make a change in the 

 voice, or there might be disturbances of the pupil of the eye due to implication of 

 the sympathetic. 



Should the tumor enlarge posteriorly the pressure on the trachea would inter- 

 fere with the breathing. If the tumor is large this pressure would involve the oesoph- 

 agus and there might be difficulty in swallowing. Compression of the thoracic duct 

 is said to have led to rapid wasting. 



If the aneurism bulges downward it impinges on the left bronchus, which may 

 lead to its dilation and cause bronchorrhcea. A large tumor could also interfere with 

 the flow of blood through the pulmonary arteries and so give rise to congestion and 

 dyspnoea. 



An enlargement upward would involve the innominate and left carotid and 

 subclavian arteries and also the left innominate vein. Interference with the arteries 

 and veins of the neck and upper extremity frequently gives rise to changes in the 

 pulse on the affected side and also to venous congestion or even oedema. Changes 

 in the voice or even its loss also occur. The sac as it passes upward may show 

 itself in the suprasternal notch. 



In all aneurisms of the arch cough is apt to be a prominent symptom. It is 

 often paroxysmal. It is to be accounted for by pressure on the trachea or laryngeal 

 nerves. Difficulty in breathing and swallowing may arise in deep-seated small tumors 

 growing backward and downward. This may be somewhat relieved by sitting up or 

 leaning forward, while reclining or lying on the back may be unendurable. 



The great amount of distress which these aneurisms of the arch of the aorta may 

 give rise to is readily appreciated when one recalls that there is only a distance of 5 

 or 6 cm. (2^ in.) between the upper edge of the sternum and the anterior surface 

 of the vertebral column, a space already filled with important structures. 



The Descending Aorta. The remaining portion of the aorta, from the lower 

 border of the fourth thoracic vertebra down, is called the descending aorta. It is 

 divided into the thoracic and abdominal portions. The thoracic aorta begins at the 

 lower border of the fourth and ends at the lower border of the twelfth thoracic 

 vertebra. At its beginning it lies on the left side of the vertebral column, but as it 

 descends it comes somewhat forward but does not reach the middle line. It lies in 

 the posterior mediastinum more toward the left side than toward the right. 



Relations. In front above are the pericardium, the pulmonary artery, left bron- 

 chus, left pulmonary veins, and oesophagus. Behind is the vertebral column. To 

 the right are the oesophagus above, the vena azygos major, and the thoracic duct. 

 To the left are the left lung and the pleura, which it grooves, and a quite small 

 portion of cesophagus below. 



Aneurism, when involving the thoracic aorta, tends to cause absorption of the 

 vertebrae and ribs, and to present posteriorly; as the space is not so restricted as is 

 the case higher up the tumor has a freer opportunity to expand and the suffering is 

 not so great nor are the symptoms so marked. It may rupture into the left pleura or 

 cesophagus and may erode through the bodies of the vertebrae into the spinal canal. 



These aneurisms may exist many years and attain a large size. 



