Henry Gray (18251861). Anatomy of the Human Body. 1918.
The further subdivisions of the bronchi will be considered with the anatomy of the lung.
FIG. 962 Bronchi and bronchioles. The lungs have been widely separated and tissue cut away to expose the air-tubes. (Testut.) (See enlarged image)
If a transverse section be made across the trachea a short distance above its point of bifurcation, and a birds-eye view taken of its interior (Fig. 963), the septum placed at the bottom of the trachea and separating the two bronchi will be seen to occupy the left of the median line, and the right bronchus appears to be a more direct continuation of the trachea than the left, so that any solid body dropping into the trachea would naturally be directed toward the right bronchus. This tendency is aided by the larger diameter of the right tube as compared with its fellow. This fact serves to explain why a foreign body in the trachea more frequently falls into the right bronchus. 1
FIG. 963 Transverse section of the trachea, just above its bifurcation, with a birds-eye view of the interior. (See enlarged image)
Structure (Fig. 964).The trachea and extrapulmonary bronchi are composed of imperfect rings of hyaline cartilage, fibrous tissue, muscular fibers, mucous membrane, and glands.
The cartilages of the trachea vary from sixteen to twenty in number: each forms an imperfect ring, which occupies the anterior two-thirds or so of the circumference of the trachea, being deficient behind, where the tube is completed by fibrous tissue and unstriped muscular fibers. The cartilages are placed horizontally above each other, separated by narrow intervals. They measure about 4 mm. in depth and 1 mm. in thickness. Their outer surfaces are flattened in a vertical direction, but the internal are convex, the cartilages being thicker in the middle than
Note 1. Reigel asserts that the entry of a foreign body into the left bronchus is by no means so infrequent as is generally supposed. See also Med.-Chi. Trans., lxxi, 121. [back]