2l8 



RESPIRATORY EXCURSION OF THE LUNGS. 



FIG. 83. Sibson's Thoracometer. 



in the lower part. Valentin found that during deepest inspiration in 

 men, the circumference of the thorax at the level of the ensiform carti- 

 lage increased between yV and y; Sibson found this increase to be yV 

 at the level of the nipples. 



Various instruments have been devised to determine the degree of movement 



(elevation or depression) made by a definite part of the thorax during respiration. 



The cyrtometer of Woillez is quite useful : A measuring chain with stiffly movable 



links is applied to the outer sur- 

 face of the thorax in a definite 

 direction, for example, trans- 

 versely at the level of the epi- 

 gastrium or the nipples, or per- 

 pendicularly through the mam- 

 millary or the axillary line. In 

 two places the links are loosely 

 movable, permitting a removal 

 of the chain without changing its 

 form as a whole. The inner out- 

 line of the chain is traced on a 

 sheet of paper, and the form of 

 the thorax is thus obtained (Fig. 

 82). If the instrument is first 

 applied in the state of expiration, 

 and then during inspiration, there 

 is obtained a diagrammatic repre- 

 sentation of the extent of move- 

 ment in the various parts of the 

 thorax. The same purpose is 

 served by shadow-diagrams or 

 photograms taken at the various 

 periods of respiration. A compli- 

 cated apparatus has also been 



constructed of numerous little rods, which rest on the thorax and rise and 

 fall with the respiratory movement and can be fixed in a given position. 



The tkoracometer of Sibson (Fig. 83) measures the elevation of selected parts 

 of the sternum. It consists of two metal rods, joined at right angles, of which one 

 (A) is applied to the spinal column. On B is the movable arm C, which carries 

 at its end the toothed bar (Z) directed perpendicularly downward. The latter is 

 supplied with a spring, and ends below in a ball, which rests upon that part of 

 the sternum to be investigated. The toothed bar, by means of a small cogwheel, 

 moves the indicator (o) , which shows the excursions of the sternum on an enlarged 

 scale. 



RESPIRATORY EXCURSION OF THE LUNGS. 



The boundaries and the size of the lungs in a state of rest on the ante- 

 rior surface of the thorax are shown in Fig. 34. The shaded bounda- 

 ries L L indicate the borders of the lungs, while the dotted lines 

 P P show the extent of the parietal pleura (boundaries of the pleural 

 cavity). In the living subject the extent of the lungs can be determined 

 by percussion, that is, by striking the chest- wall (through an interposed 

 thin plate of horn: Piorry's plessimeter) by means of a small cushioned 

 hamrner (Wintrich's percussion-hammer). Wherever pulmonary tissue 

 containing air lies in contact with the chest- wall, a sound is obtained 

 like that produced by striking a vessel containing air (resonant per- 

 cussion-note). Where the underlying parts contain no air, the sound 

 is like that produced by striking the thigh (flat percussion-note). If 

 the parts containing air are thin, or are partly deprived of their air, the 

 note is dull. 



Fig. 84 in connection with Fig. 34 shows the boundaries of the lungs 



