0 12 X 16 8 X 10 6 X 7
Length trachea, cm. 12.0 10.0 6.0 4.0
Length right bronchus 2.5 2.5 2.0 1.5
Length left bronchus 5.0 5.0 3.0 2.5
Length upper teeth to trachea 15.0 23.0 10.0 9.0
Length total to secondary bronchus 32.0 28.0 19.0 15.0

In considering the foregoing table it is to be remembered that in life
muscle tonus varies the lumen and on the whole renders it smaller. In
the selection of tubes it must be remembered that the full diameter of
the trachea is not available on account of the glottic aperture which
in the adult is a triangle measuring approximately 12 X 22 X 22 mm.
and permitting the passage of a tube not over 10 mm. in diameter
without risk of injury. Furthermore a tube which filled the trachea
would be too large to enter either main bronchus.

The normal movements of the trachea and bronchi are respiratory,
pulsatory, bechic, and deglutitory. The two former are rhythmic while
the two latter are intermittently noted during bronchoscopy. It is
readily observed that the bronchi elongate and expand during
inspiration while during expiration they shorten and contract. The
bronchoscopist must learn to work in spite of the fact that the
bronchi dilate, contract, elongate, shorten, kink, and are dinged and
pushed this way and that. It is this resiliency and movability that
make bronchoscopy possible. The inspiratory enlargement of lumen opens
up the forceps spaces, and the facile bronchoscopist avails himself of
the opportunity to seize the foreign body.

THE ESOPHAGUS

A few of the anatomical details must be kept especially in mind when
it is desired to introduce straight and rigid instruments down the
lumen of the gullet. First and most important is the fact that the
esophageal walls are exceedingly thin and delicate and require the
most careful manipulation. Because of this delicacy of the walls and
because the esophagus, being a constant passageway for bacteria from
the mouth to the stomach, is never sterile, surgical procedures are
associated with infective risks. For some other and not fully
understood reason, the esophagus is, surgically speaking, one of the
most intolerant of all human viscera. The anterior wall of the
esophagus is in a part of its course, in close relation to the
posterior wall of the trachea, and this portion is called the party
wall. It is this party w