Trachea
or WINDPIPE, the tube extending from the larynx, or organ of the voice, and from the level of the fifth cervical vertebra to the third dorsal vertebra, at which latter point the trachea bifurcates or divides into two main bronchi or divisions, one supplying each lung with air tubes. The average length of the trachea is 4½ inches and its diameter about three-fourths of an inch. the latter measurement being greater in males than in females. The trachea consists of fibrous membranes united by elastic cartilaginous rings, rendering the tube flexible and patent. The cartilages are circular but imperfect rings, each being joined posteriorly by fibrous membrane. They vary from 16 to 20 in number. The muscular fibres of the trachea are of longitudinal and transverse arrangement. The trachea is lined with which is ciliated. The trachea receives mucous membrane, the epithelium of blood from the inferior thyroid arteries, and nerves from the pneumogastric and recurrent trunks, and also from the sympathetic system. The right bronchus, or is wider and shorter than the left. It one of the main divisions of the trachea, enters the lung opposite the fourth dorsal vertebra. The left bronchus is smaller and more oblique than the right and enters the left lung at the level of the fifth dorsal vertebra.
Diseases and Injuries of the Trachea.
The trachea is liable to inflammation and its products, and frequently suffers from extension of disease from the larynx.
Acute inflammation may occur as an idiopathic affection, or a symptom of other disease, as smallpox, measles, typhus, tuberculosis, croup, etc. The symptoms are pain in the windpipe from the top of the sternum, expectoration of mucus, sometimes in regular rings, and a peculiar brazen-like cough. When confined to the larynx there is no hoarseness. Chronic inflammation usually accompanies follicular pharyngo-laryngitis, tuberculosis, and syphilis. Constriction of the trachea may be produced by aneurismal or other tumors pressing externally on the trachea; or the symptoms