,8 42 HUMAN ANATOMY. 



The symptoms that would suggest arrest in the larynx are violent cough, alter- 

 ation or loss of voice, frequent spasm, stridor, and rapidly increasing dyspnoea (from 

 swelling and oedema of the mucosa). In the trachea a foreign body is apt to cause 

 mo.lcrate but persistent cough, hurried respiration, occasional reflex spasm of the 

 glottis, and slight dyspnoea. Arrest in a division or subdivision of a bronchus, if 

 fhe body is large enough to plug it, will cause absence of vocal and respiratory 

 sounds over the area involved, collapse of the lung, and flattening of the side of the 

 thorax. Later symptoms will be due to irritation (hyperaemia and catarrh), fol- 

 lowed by infection (inflammation and ulceration) and, in cases of long standing, 

 possibly by the involvement of neighboring structures or organs (the lungs or 

 pleura, the aorta or vena cava, the pericardium, or the oesophagus). The relatively 

 unyielding walls of the air-passages render this termination less common than in 

 cases of oesophageal impaction of foreign bodies. Spontaneous expulsion during a 

 coughing spell may take place, or operation may be needed. (See thyrotomy, 

 laryngotomy, tracheotomy, bronchotomy. ) 



The bronchi begin at the bifurcation of the trachea, about opposite the space 

 between the fourth and fifth thoracic vertebras. This is behind the lower part of the 

 arch of the aorta and on a horizontal line passing through the sternal angle (angu- 

 lus Ludovici) and the root of the spine of the scapula. As at their origin they are 

 nearer the posterior than the anterior wall of the thorax, auscultatory sounds in the 

 primary bronchi can best be heard between the scapulae and about the level of the 

 inner ends of their spines. 



The most frequent as well as the most serious forms of compression of the air- 

 passages are found within the thorax. In the neck, even in the presence of large 

 tumors or swellings, the feeble resistance of the skin and other tissues may permit 

 the trachea to escape ; but within the thorax, between the spine and the unyielding 

 sternum, even small growths may cause serious symptoms of obstruction. 



Thus the group of lymph-nodules surrounding the bifurcation may, when dis- 

 eased, make pressure upon either the trachea or bronchi, as may aneurisms of the 

 aorta or innominate, or tumors of the posterior mediastinum, or even a dilated left 

 auricle. 



In chronic interstitial pneumonia attended by great increase in the connective- 

 tissue elements of the lung, followed, as is invariably the case, by contraction of 

 such tissue, the atmospheric pressure retains the lung in contact with the inner sur- 

 face of the chest in spite of the pull of the atrophying fibrous tissue. The force is, 

 therefore, exerted on the bronchi, the walls of which are dragged apart, forming 

 great cavities (bronchieclasis). Such cavities may also be due to dilatation under 

 increased pressure from within, as when a foreign body or an aneurism occludes one 

 bronchus ; or to chronic disease and weakening of the bronchial walls. 



Asthma of the spasmodic type may be due to reflex pneumogastric irritation 

 causing contraction of the muscular tissue in the walls of the smaller bronchi. It 

 bould !>< n..tr<l that the transverse muscular fibres (trachealis muscle) connecting 

 the ends of the tracheal cartilages have in the bronchioles become converted into a 

 complete circular muscular coat, and are found even in divisions so small that the 



la^e has disappeared. 



nchofoniy. The relations of the bronchi (page 1857) show that in case of 



impaction <>f a f. nvi-n body in or just below a primary bronchus it might be reached 



1>\ a posterior thorarotomy done at the level of the fourth to the sixth or seventh 



rib. The flap of soft parts is three inches square, its base being about over the 



Melu.il Butter on the side to be operated upon. The underlying ribs are sepa- 



1 from the pleura and divided. The proximity of the great azygos vein on the 

 rii;ht >i<ie, and of tlie ar.h ( .f the aorta, the descending aorta, the oesophagus, and 

 the left auri.le on the left, must be remembered. It is more difficult to retract the 

 pleura on the n-ht >idr BO M to expose the bronchus. Bryant has called attention 

 to the ioll..\\ii>v; anatomical points bearing upon this operation, whether it is under- 

 taken for the removal of a foreign l>o<|\- from a bronchus or the oesophagus, or for 

 posterior me. li., .tinal tmn.r> <>r aUcess, or for the relief of pressure from enlarged 

 bronchi*] J md- : tin- lower portion of the fourth dorsal vertebra is the boundary 

 line between the posterior mediastinum and the lower part of the superior medias- 



