2O2 



APPLIED ANATOMY. 



Owing to the fibrous nature of the pericardium it will not expand suddenly. 

 While only about a pint of liquid can be injected into the normal pericardial cavity 

 after death, if a chronic effusion exists in a living person as much as three pints may 

 be present. 



Sudden effusion occurring in the living patient will cause obstruction of the cir- 

 culation at the base of the heart; it may by pressure on the bronchi at the bifurcation 

 produce suffocative symptoms and by pressure on the oesophagus difficulty in swallow- 

 ing. The lungs are displaced laterally, and the stomach and liver downward. The 

 largest effusions are slow in their formation. 



Pressure on the left recurrent laryngeal nerve as it winds around the aorta 

 sometimes produces alteration or loss of the voice. 



In children, according to Osier, the praecordia bulges and the anterolateral region 

 of the left chest becomes enlarged as does also the area of the cardiac dulness. 



Paracentesis of the Pericardium. Tapping the pericardium by means of a 

 trocar or aspirating needle must be carefully done, or the pleura may be punctured. 



FIG. 218. View of the pericardium, slightly distended, and its relations to the bony thorax. 



The part of the pericardium in contact with the chest-wall and not covered by 

 pleura is very small. It embraces the space between the two pleurae from the fourth 

 to the seventh ribs. This may be defined by three lines, one in the midline, another 

 from the middle of the sternum opposite the fourth rib to the costosternal junction 

 of the seventh rib, and a third joining these two passing through the articulation of 

 the xiphoid cartilage (Fig. 219). 



The left pleural sac may be i cm. farther from the edge of the sternum than the 

 right. Thus it is seen that there is hardly a point where a needle can be introduced 

 with the certainty of avoiding the pleura. The safest point is probably close to the 

 left edge of the sternum in the sixth interspace. This interspace may not extend 

 to the sternum, but even if the cartilages are in contact a needle could probably be 

 introduced at this point. As the pericardium is distended it carries the lungs and to 

 a less extent the pleura outwards and increases the area available for puncture both 



