166 ANATOMY AND DISEASES OF THE NECK. 



be excised with the intervening licrament. The remaining portion will then be strong 

 enough to retain the perfect arched form of the trachea. 



If the orifice is only to be kept open Avhile some ibreigu body is extracted, or tumour 

 removed, nr ulcer healed, or inflammation subdued, notliing more is necessary than to 

 keep the lips of the wound a little apart, by passing some thread through each, and 

 sli<rhtly everting them, and tying the threads to the mane. 



If, however, there is any permanent obstruction, a tube will be necessary. It should 

 be two or three inches long, curved at the top, and the external orifice turning down- 

 wards with a little ring on each side, by which, through the means of tubes, it may 

 be retained in its situation. 



The purpose of the operation being answered, the flaps of integument must be 

 brought over the wound, the edges, if necessary, diminished, and the parts kept in 

 apposition by a few stitches. The cartilage will be perfectly reproduced, only the 

 lings will be a little thicker and wider. 



The following account will illustrate the use and the danger of the tracheotomy 

 tube. A mare at Alfort had great distortion of the rings of the trachea. She breathed 

 with difficultv. She became a roarer almost to suffocation, and was quite useless. 

 Tracheotomjf was effected on the distorted rings, and a short canula introduced. She 

 was so much relieved that she trotted and galloped immediately afterwards without 

 the slightest distress. Six months later she again began to roar. It seemed that the 

 rings were now distorted below the former place. 



M. Barthelemy introduced another canula, seven inches long, and which reached 

 below the new distortion. She was once more relieved. She speedily improved in 

 condition, and regularly drew a cabriolet at the rate of seven or eight miles in the 

 hour; and this she continued to do for three years, when the canula became accident- 

 ally displaced in the night, and she was found dead in the morning. 



THE BRONCHIAL TUBES. 



The wind])ipe has been traced through its course down the neck into the chest. It 

 is there continued through the mediastinum to the base of the heart, and then divided 

 into two tubes corresponding with the two divisions of the lungs — the Bronchial 

 Tubes. These trimks enter deeply into the substance of the lungs. They presently 

 subdivide, and the subdivision is continued in every direction, until branches from the 

 trachea penetrate every assignable portion and part of the lungs. They are still air- 

 passages, carrying on this fluid to its destination, for the accomplishment of a vital 

 purpose. 



They also continue exposed to pressure ; but it is pressure of a new kind, a pressure 

 alternately applied and removed. The lungs in which they are embedded alternately 

 contract and expand ; and these tubes must contract and expand likewise. Embedded 

 in the lungs, the cartilaginous ring of the bronchi remains, but it is divided into five 

 or six segments connected with each other. The lungs being compressed, the seg- 

 ments overlap each other, and fold up and occupy little space ; but the principle of 

 elasticity is ftill at work; and as the pressure is removed, they start again, and 

 resume their previous form and calibre. It is a beautiful contrivance, and exquisitely 

 adapted to the situation in whicli these tubes are placed, and the functions they havp 

 lo discharge. 



But we must pause a little and consider the structuie nnd functions of the chest. 



