s forward, passing
through the hiatus in the diaphragm anterior to and to the left of the
aorta. The lower third of the esophagus in addition to its anterior
curvature turns strongly to the left, so that an esophagoscope
inserted from the right angle of the mouth, when introduced into the
stomach, points in the direction of the anterior superior spine of the
left ileum.

It is necessary to keep this general course constantly in mind in all
cases of esophagoscopy, but particularly in those cases in which there
is marked dilatation of the esophagus following spasm at the diaphragm
level. In such cases the aid of this knowledge of direction will
greatly simplify the finding of the hiatus esophageus in the floor of
the dilatation.

The extrinsic or transmitted movements of the esophagus are
respiratory and pulsatory, and to a slight extent, bechic. The
respiratory movements consist in a dilatation or opening up of the
thoracic esophageal lumen during inspiration, due to the negative
intrathoracic pressure. The normal pulsatory movements are due to the
pulsatile pressure of the aorta, found at the 4th thoracic vertebra
(24 cm. from the upper teeth in the adult), and of the heart itself,
most markedly felt at the level of the 7th and 8th thoracic vertebrae
(about 30 cm. from the upper teeth in adults). As the distances of all
the narrowings vary with age, it is useful to frame and hang up for
reference a copy of the chart (Fig. 46).

The intrinsic movements of the esophagus are involuntary muscular
contractions, as in deglutition and regurgitation; spasmodic, the
latter usually having some pathologic cause; and tonic, as the normal
hiatal closure, in the author's opinion may be considered. Swallowing
may be involuntary or voluntary. The constrictors are anatomically not
considered part of esophagus proper. When the constrictors voluntarily
deliver the bolus past the cricopharyngeal fold, the involuntary or
peristaltic contractions of the esophageal mural musculature carry the
bolus on downward. There is no sphincter at the cardiac end of the
esophagus. The site of spasmodic stenosis in the lower third, the
so-called cardiospasm, was first demonstrated by the author to be
located at the hiatus esophageus and the spasmodic contractions are of
the specialized muscle fibers there encircling the esophagus, and
might be termed "phrenospasm," or "hiatal esophagismus." Regurgitation
of food from the stomach is normally prevented