of the gastrointestinal
tract for other conditions, because traction diverticula usually cause
no symptoms. Unless a very large esophagoscope be used, a traction
diverticulum may easily be overlooked in the mucosal folds. Careful
lateral search, however, will reveal the dilatation, and the localized
periesophageal fixation may be demonstrated. The subdiverticular
esophagus is readily followed, its lumen opening during inspiration
unless very close to the diaphragm, which is very rare. Perhaps most
cases will be discovered by the roentgenologist. It has been said that
traction diverticula are more readily demonstrated in the
roentgenologic examination, if the patient be placed with pelvis
elevated.

_Pulsion diverticulum of the esophagus_ is an acquired hernia of the
mucosa between the circular and oblique fibers of the inferior
constrictor muscle of the pharynx. A congenital anatomic basic factor
in etiology probably exists. The pouching develops in the middle part
of the posterior wall, between the orbicular and oblique fibers of the
cricopharyngeus muscle, at which point there is a gap, leaving the
mucosa supported only by a not very resistant fascia (Fig. 100). When
small, the sac is in the midline, but with increase in size, it
presents either to the right or the left side, commonly the latter.
The sac may be very small, or it may be sufficiently large to hold a
pint or more, and to cause the neck to bulge when filled. When large,
the pouch extends into the mediastinum. It will be seen that
anatomically the pulsion diverticulum has its origin in the pharynx;
the symptoms, however, are referable to the esophagus and the
subdiverticular esophagus is stenosed by compression of the pouch;
therefore, it is properly classified as an esophageal disease.

[FIG. 100.--Schema illustrative of the etiology of pressure
diverticula. O, oblique fibers of the cricopharyngeus attached to the
thyroid cartilage, T. The fundiform fibers, F, encircle the mouth of
the esophagus. Between the two sets of fibers is a gap in the support
of the esophageal wall, through which the wall herniates owing to the
pressure of food propelled by the oblique fibers, O, advance of the
bolus being resisted by spasmodic contraction of the orbicular fibers,
F.]

_Etiology_.--Pressure diverticula occur after middle life, and more
often in men than in women. The hasty swallowing of unmasticated food,
too large a bolus, defective or artificial teeth, flacc