As mentioned above, it is sometimes more convenient to remove the thoracic organs en masse, either alone, or in association with the neck organs. When this is done the dissection follows the method of Letulle (see above), or the organs may be separated and sectioned according to the methods just given.
The section of the heart usually precedes that of the lungs, in order that the blood-content of the former may be more correctly estimated. Under certain conditions it may be more convenient or expedient to section the lungs first, beginning with the left one.
When the neck-organs are not removed the section of the thorax closes with the examination of the aorta, oesophagus, thoracic duct and thoracic vertebrae. The blood-vessels and œsophagus are opened with the curved scissors, from above downward, the contents noted, and the walls examined. The thoracic duct is best dissected out from the right side, by cutting along the right side of the aorta and turning the latter over to the left. The duct is more easily recognized at its lower end. It may be inflated with the blow-pipe, or opened with a probe and fine probe-pointed scissors. Sometimes the duct can be most easily found by removing the left lung and then turning the right lung over into the left pleural cavity. The posterior mediastinal tissues are put on a stretch, so that the duct can be recognized through the pleura. For the examination of the left subclavian vein the left clavicle should be removed.
II. POINTS TO BE NOTED IN THE EXAMINATION OF THE THORAX.
1. Thoracic Cavity. Presence of gas or air (pneumothorax, infections with colon bacillus, gas-forming bacillus, proteus, etc.), relative degree of pressure, odor, etc. Measure contents of each pleural sac; note character of fluid (clear, turbid, bloody, chyliform, chylous, purulent, fibrino-purulent). Normally the pleuræ are moist-shining, smooth, grayish, transparent; only a few drops of fluid found in the cavities. In cases of slowly progressive cardiac insufficiency large amounts of clear fluid may collect in the cavities just before death. Non-inflammatory collections of fluid also occur in general œdema. In these conditions the pleuræ are not cloudy or dull, while in the case of inflammation the pleural surfaces are dry, cloudy, dull-shining, injected, rough or covered with fibrinous or purulent exudate. Examine pleural surfaces particularly for evidences of inflammation, recent and old tuberculosis, primary and secondary neoplasms (carcinoma).
2. Position of Thoracic Organs. Locate anterior borders of lungs, apex and borders of heart. The normal lung collapses after the removal of the sternum. How much of the pericardial sac is left uncovered by the lungs?
3. Anterior Mediastinum. Note character of connective-tissue, amount and color of fat-tissue, number and size of lymphnodes, occurrence of œdema or emphysema. An artificial œdema may be caused by the injection of large quantities of salt solution in the pectoral region just before death. An artificial emphysema may be produced by the removal of the sternum. The condition of the large veins in the upper portion of the mediastinum should be noted before the heart is removed. Are they lax, moderately full, or distended? Secondary tumors, hemorrhages, abscesses, œdema and emphysema are the most common pathologic conditions.
4. Thymus. The writer believes that the weights usually given for the thymus in the new-born are too high, and that 7-10 grms. represents the usual normal weight. A gland weighing 20 grms. or more must be regarded as enlarged. The organ reaches its fullest development at the end of the second year. Atrophy begins then, developing slowly up to the age of puberty, after that more rapidly. In adults the thymus normally consists of a mass of adipose tissue containing lymphoid nodules, in some of which corpuscles of Hassall persist to old age. Postmortem softening should not be mistaken for abscesses. The most important pathologic change is hypertrophy. Pressure of the enlarged gland upon the trachea, nerves or great vessels may cause thymic stridor, asthma, or thymic death (“lymphatic constitution”). Enlargement of the thymus may occur in “status lymphaticus,” exophthalmic goitre, cretinism, myxœdema, Addison’s disease, acromegaly, myasthenia gravis, epilepsy, scorbutus, rachitis, tonsillar hyperplasia, adenoids, congenital syphilis, Hodgkin’s disease, leukæmia, anencephaly, anæmia, acute infections, or it may exist as an independent affection. Oedema, congestion, inflammation, tuberculosis, neoplasms, etc., may also cause an enlargement. Absence of the thymus has been observed. Primary and secondary forms of atrophy in association with marasmus occur in children. Note relation of size of thymus to condition of child; atrophy of the organ is usually coincident with marasmus. Inflammation, tuberculosis, cysts, primary and secondary neoplasms, gummata, etc., are not common.
5. Pericardium. Note tension of sac, fluctuation, adhesions, thickness, character of inner surface, contents (amount, color, odor, presence of fibrin, blood or pus, gas). Normally there are about 5-10 c. c. of clear yellow fluid in the sac. Both peri- and epicardium normally are moist-shining, smooth, grayish and transparent. Large amounts of clear watery fluid may collect in the pericardial sac in slow death in cases of chronic valvular lesions, chronic nephritis, bronchitis and emphysema, but the surface of the peri- and epicardium remains smooth and shining. In inflammatory increase of the pericardial fluid the serous surfaces are dull, cloudy or dry, and may be covered with a layer of fibrin, the fluid is more or less cloudy and contains flakes or strings of fibrin, or may be purulent. The fibrinous exudate may be very extensive and from the movement of the heart be drawn out into bands, threads or villus-like prominences (cor hirsutum or villosum). Pericarditis is common in acute rheumatism, septicæmia, pyæmia, puerperal fever, osteomyelitis, pneumonia, and as a terminal infection in cardiac and renal disease. Tuberculosis is one of the most common causes of purulent, fibrinous and hemorrhagic pericarditis, particularly of the cor villosum. Examine surfaces for tubercles. The presence of blood in the pericardial exudate points usually to tuberculosis or malignant neoplasm, but in small amount may be found in various infections and intoxications. The age of the pericarditis may be judged by the amount of organization of the exudate, adhesions, thickenings, etc. “Milk spots,” “soldier’s spots,” “tendinous patches” or “friction scleroses” represent hyaline thickenings of the pericardium due to old pericarditis. Total synechia or atresia of the cavity may occur. As the result of calcification of an old pericarditic exudate the heart may be surrounded by a calcareous sheath (“stony heart,” “petrified heart”). Hæmopericardium results from the rupture of the heart, aorta, pulmonary artery or coronary vessel. Petechiæ of the peri- and epicardium are found in pyæmia, septicæmia, hæmophilia, scurvy, severe anæmia, leukæmia, chronic nephritis, and death from suffocation and various intoxications. Pneumopericardium may be due to perforating wounds, or to perforations from lungs, stomach or œsophagus, or to infections with gas-forming bacilli. Malformations are rare (diverticula, ectopia). Tuberculosis is usually secondary. Gummata are rare. Actinomycosis is usually secondary to actinomycosis of the neck or lungs. Primary neoplasms are rare. Secondary carcinoma and sarcoma (especially lymphosarcoma) are more frequent. Cysticercus, trichina and echinococcus are rare.
6. Heart. Note more carefully its position, whether displaced to right or left, location of apex, borders, etc. Relative size compared to cadaver’s right fist, which is usually a little smaller than the heart. Weight and measurements:—(The heart should be weighed after it has been opened, and its cavities freed from blood and clots.)