Elements of anatomy and physiology : prepared for the use of schools and colleges / by W. S. W. Ruschenberger ; from the text of Milne Edwards and Achille Comté.

  • Henri Milne-Edwards
Date:
1852
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Licence: Public Domain Mark

Credit: Elements of anatomy and physiology : prepared for the use of schools and colleges / by W. S. W. Ruschenberger ; from the text of Milne Edwards and Achille Comté. Source: Wellcome Collection.

Provider: This material has been provided by the National Library of Medicine (U.S.), through the Medical Heritage Library. The original may be consulted at the National Library of Medicine (U.S.)

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    12. The larynx is prolonged inferiorly into a long tube, called the trachea or wind pipe, which descends through the neck, and enters into the thorax. This tube is formed by a series of cartil- aginous rings, and is lined internally by a thin membrane, which also lines the larynx, and is continuous with that of the pharynx. The cartilaginous rings of the trachea are very elastic, and prevent this air canal from being effaced, that is, from having its sides pressed together, and thus offer an obstacle to the passage of the air. 13. At its lower extremity, the trachea is divided into two branches, one going to each of the two lungs; they are called bronchia. 14. Soon after they enter the lungs, these bronchia? are sub- divided, and ramify in an almost infinity of branches, so as to furnish every pulmonary cell with a little branch, which opens into it, and conveys there, the air necessary to respiration. 15. The instrument which causes the air to pass through these tubes, and to enter the lungs, or to go out from them is the thorax, (Fig. 12.) 16. The mechanism by which this phenomenon is produced is very simple, and in almost every respect resembles the play of a pair of bellows, except that the air escapes by the same passage that it entered the lungs, which « is not the case in the bellows. 17. The lungs are lodged in a great cavity called the chest, or thorax, the sides of which are moveable, and so arranged,as to Explanation of Fig. 12.—The thorax. On theright side of the cut are seen the muscles which fill the spaces between the ribs; on the left side, they have been removed,—cv. the vertebral column, the greater part of which is con- cealed by the sternum, (s),—c,c,c.c, ribs of the right side,—mi, intercostal muscles,—s, the sternum,—d, the diaphragm ; a part of which is seen below Iho thorax, and between the ribs on the right side, but it is concealed on the left by the ribs and intercostal muscles. J 2. Wh;it is the trachea ? What is its structure ? 13. What are the bronchise? 14. How do the branchiae terminate? 15. What causes the air to pass through the lungs? 16. To what is this mechanism comparable ? 17. Where are the lungs situated ? What happens when tne thorax dilates ? How does the air escape from the lungs ?
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