PLEUK^E AND PERICAKDIUM. 1067 



limits of the pleural cavities and the position of the anterior mediastinum 

 can now be examined, together with the position of the heart and great 

 vessels in relation to the lungs and the walls of the thorax (p. 299). That 

 this may be done more effectually, the lungs should be inflated through a 

 tube introduced into the throat or wind-pipe, and their different positions 

 and relations in the inflated and collapsed state attentively examined. The 

 body of the sternum is next to be separated from the manubrium, and, 

 together with the adherent costal cartilages of the left side, removed ; and 

 on the fragment of the thoracic wall thus separated the triangularis sterni 

 muscle and its relation to the internal mammary artery may be further 

 examined. The dissectors will then complete their examination of the 

 anterior mediastinum, observing in its upper part the remains (if any) of the 

 thymus body, and will carefully study the remaining reflections of the 

 pleura. The heart within the pericardium is also to be observed (p. 

 313). In making this dissection the student may be required to separate 

 the parietal from the pulmonary pleura, by breaking up with his fingers, or 

 the handle of the knife, the inflammatory adhesions which are often met 

 with. Great care must be taken to clean with a sponge and wash the interior 

 of the chest and the surface of the lungs, first with water, and subsequently 

 with preserving fluid (p. 892). 



2. Parts External to the Pericardium. The phrenic nerve will be seen 

 on each side beneath the pleura in front of the root of the lung, and is to be 

 dissected out ; when its relation to the internal mammary artery, which it 

 crosses at the upper part of the chest, and the branch of the latter artery 

 which accompanies it, are to be observed (p. 640). The strustures above the 

 pericardium are then to be dissected. Foremost will be found the inno- 

 minate veins and superior vena cava, with the termination of the vena 

 azygos, and several smaller veins, viz., the inferior thyroid, internal 

 mammary, superior intercostal, and bronchial veins (p. 453) ; and behind 

 the veins, the innominate, left carotid, and left subclavian arteries arising 

 from the arch of the aorta (pp. 340, 341 and 364). The pneumo-gastric 

 nerves will also be found, that of the right side lying external to the inno- 

 minate artery, and its recurrent branch turning round behind the subclavian 

 artery ; and that of the left side passing down in front of the arch of 

 the aorta, with its recurrent branch winding behind the aorta (p. 618). 

 Likewise crossing the arch of the aorta, on their way to the superficial car- 

 diac plexus, will be found the cervical cardiac branch of the left pneutno- 

 gastric nerve, and, usually, the superior cardiac branch from the sympathetic 

 nerve on the left side (p. 690). The other cardiac nerves, viz., the cervical 

 cardiac branch of the right pneumo-gastric nerve, the thoracic cardiac 

 branches of both pneumo-gastric nerves, the three cardiac branches of the 

 sympathetic chain of the right side, aud the middle and inferior branches of 

 the left side, are to be sought on the front and sides of the trachea, as they 

 pass down to the deep cardiac plexus. The distribution of the pneumo- 

 gastric nerves is then to be traced to the lungs and oesophagus ; and, 

 as far as possible, the posterior and anterior pulmonary plexuses are to 

 be brought into view (p. 623). After that has been done, the roots of 

 the lungs are to be fully dissected, the relations of the pulmonary arte- 

 ries and veins and the bronchi observed, and the bronchial arteries traced 

 to their origins (pp. 897 and 402). 



3. Interior of the Pericardium and Heart. The pericardium having 

 been examined on its outer aspect, is then to be cut open, and its interior 

 carefully inspected (p. 300) ; after which it is to be removed, its remains 



