The esophagus (Figure 20–1) is
a muscular tube that serves as a conduit for the passage of food
and fluids from the pharynx to the stomach. It originates at the
level of the sixth cervical vertebra, posterior to the cricoid cartilage.
In the thorax, the esophagus passes behind the aortic arch and the
left main stem bronchus, enters the abdomen through the esophageal
hiatus of the diaphragm, and terminates in the fundus of the stomach.
Its muscle fibers originate from the cricoid cartilage and pharynx above
and interdigitate with those of the stomach below. About 2–4
cm of esophagus are normally below the diaphragm. The junction between
the esophagus and stomach is maintained in its normal intra-abdominal
position by the reflection of the peritoneum onto the stomach and of
the phrenoesophageal ligament onto the esophagus. The latter is
a fibroelastic membrane that lies beneath the peritoneum, on the
inferior surface of the diaphragm. When it reaches the esophageal
hiatus, the ligament is reflected in an orad direction onto the lower
esophagus, where it inserts into the circular muscle layer above
the gastroesophageal sphincter, 2–4 cm above the diaphragm.
Anatomy of the esophagus.
Three anatomic areas of narrowing occur in the esophagus: (1)
at the level of the cricoid cartilage (pharyngoesophageal or upper
esophageal sphincter); (2) in the mid thorax, from compression by
the aortic arch and the left main stem bronchus; and (3) at the
level of the esophageal hiatus of the diaphragm (gastroesophageal
or lower esophageal sphincter).
In the adult, the distance as measured from the upper incisor
teeth to the cricopharyngeus muscle is 15–20 cm; to the
aortic arch, 20–25 cm; to the inferior pulmonary vein,
30–35 cm; and to the gastroesophageal junction, approximately
The musculature of the pharynx and upper third of the esophagus
is skeletal in type (striated muscle); the remainder is smooth muscle.
Physiologically, the entire organ behaves as a single functioning
unit, so that no distinction can be made between the upper and lower esophagus
from the standpoint of propulsive activity. As in the intestinal
tract, the muscle fibers are arranged into inner circular and outer
longitudinal layers. The arterial supply to the esophagus is quite consistent.
The upper end is supplied by branches from the inferior thyroid
arteries. The thoracic portion receives blood from the bronchial
arteries and from esophageal branches originating directly from
the aorta. The intercostal arteries may also contribute. The diaphragmatic and
abdominal segments are nourished by the left inferior phrenic artery
and by the esophageal branches of the left gastric artery.
The venous drainage is more complex and variable. The most important
veins are those that drain the lower esophagus. Blood from this
region passes into the esophageal branches of the coronary vein,
a tributary of the ...