esophagus

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esophagus

(ĭsŏf`əgəs), portion of the digestive tube that conducts food from the mouth to the stomach. When food is swallowed it passes from the pharynxpharynx
, area of the gastrointestinal and respiratory tracts which lies between the mouth and the esophagus. In humans, the pharynx is a cone-shaped tube about 4 1-2 in. (11.43 cm) long.
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 into the esophagus, initiating rhythmic contractions (peristalsis) of the esophageal wall, which propel the food along toward the stomach. The walls of the esophagus are lined with mucous glands that continue the lubrication of the food as it is conducted to the stomach. The human esophagus is about 10 in. (25 cm) long and 1 in. (2.5 cm) in diameter. See digestive systemdigestive system,
in the animal kingdom, a group of organs functioning in digestion and assimilation of food and elimination of wastes. Virtually all animals have a digestive system. In the vertebrates (phylum Chordata, subphylum Vertebrata) the digestive system is very complex.
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Esophagus

A section of the alimentary canal that is interposed between the pharynx and the stomach. Because of divergent specializations in the various vertebrates, the esophagus cannot be described in general terms and is not always distinguishable.

In humans it is a tube running the full length of the neck and the thorax, held in its position ventral to the vertebral centra by a tunica adventitia of loose connective tissue. It has an inner lining of folded mucous membrane with an exceptionally thick lamina propria, a submucosa of elastic and collagenous connective tissue, and two layers of muscle. The musculature is striated in the anterior third of its length, unstriated in the posterior third, and variably intermixed in the middle. It is supplied with autonomic nerve fibers.

Although normally collapsed, the human esophagus is capable of considerable distension during the rapid passage of swallowed material, under which condition the folds of mucous membrane and lamina propria are temporarily smoothed out. Numerous microscopic esophageal glands open into the lumen, extending their compound tubules out into the submucosa.

In humans the transition from the esophagus to the stomach occurs quite abruptly at the diaphragm. The pharynx narrows posteriorly like a funnel and the foregut may thereupon enlarge, but much of what appears to be stomach may have an esophageal character histologically. See Digestive system

Esophagus

 

the part of the alimentary canal of animals and man through which food passes. In invertebrates, the esophagus begins at the mouth opening or pharynx, extending in some animals to the beginning of the midgut or glandular stomach and in others to the masticatory stomach. In some flatworms and annelids, the esophagus is a tube connecting the pharynx to the midgut. Among mollusks, the esophagus is well developed only in gastropods and cephalopods, forming in many of these mollusks an ingluvies (crop). In arachnids and insects, the esophagus begins at the pharynx, and in crustaceans and myriapods, at the mouth opening. In higher crustaceans, king crabs, and most insects, the posterior section becomes the masticatory stomach, in which food is ground up. In echinoderms, the esophagus connects the mouth opening to the midgut; in most vertebrates, it connects the pharynx to the stomach. The length of the esophagus varies with the length of the cervical and thoracic parts of the trunk. In birds the esophagus is very long and forms the crop.

In man, the esophagus is a muscular tube about 25 cm long. It enters the abdominal cavity through the esophageal opening of the diaphragm and reaches the cardia. The esophagus narrows in three places: where it leaves the pharynx, where the trachea becomes divided into bronchi, and where the esophagus passes through the diaphragm. The walls of the esophagus consist of a layer of areolar tissue, an underlying muscular layer of external longitudinal and internal circular fibers, and a submucous layer and mucous membrane; the glands are situated in the submucous layer and the mucous membrane. The esophagus is innervated by the sympathetic, vagus, and cerebrospinal nerves. It is supplied with blood through the arterial branches of the inferior thyroid and subclavian arteries, thoracic aorta, and left gastric artery. The muscles of the esophagus contract reflexly during every swallowing movement. The contractions are in the form of waves originating in the upper part of the esophagus and extending along the entire length. The muscles arranged in rings contract successively, causing the bolus to move downward. Solid food passes through the esophagus in eight to nine sec on the average, and liquid food in one to two sec.

Diseases of the esophagus, which may be congenital or acquired, include such anomalies as atresia, congenital stenosis, and cysts; esophageal atony and paralysis; achalasia; diverticulum; hernia of the esophageal opening of the diaphragm; and esophagitis (inflammatory lesions), which may be acute, subacute, or chronic. Peptic esophagitis (reflux esophagitis) is caused by the repeated effects of active gastric juice, bile, or intestinal or pancreatic juice on the esophageal mucosa. Other esophageal irregularities include tuberculosis, syphilis, mycotic lesions, allergic and drug-induced lesions, and the presence of foreign bodies, in addition to injuries, burns, stenosis, benign and malignant tumors, and varicosity. Among the methods used to diagnose esophageal diseases are auscultation, roentgenologic and radio-isotopic examinations, esophagoscopy, biopsy and cytologic examination, and blind bougienage. Treatment, whether dietetic, medicamentous, or surgical, depends on the nature of the disease.

REFERENCES

Vasilenko, V. Kh., A. L. Grebenev, and M. M. Sal’man. Bolezni pishchevoda. Moscow, 1971.
Gastroenterology, 2nd ed., vol. 1. Edited by H. Bockus. Philadelphia-London, 1963.

esophagus

[ə′säf·ə·gəs]
(anatomy)
The tubular portion of the alimentary canal interposed between the pharynx and the stomach. Also known as gullet.

oesophagus

(US), esophagus
the part of the alimentary canal between the pharynx and the stomach; gullet
References in periodicals archive ?
Vascular and lymphatic properties of the superficial and deep lamina propria in Barrett esophagus.
In patients who have the findings of Barrett esophagus but no evidence of dysplasia, an upper endoscopy and biopsy should be repeated in one year to confirm negative dysplasia (Fig.
The treatment goals of patients with Barrett esophagus are to eliminate the symptoms of GERD and prevent GERD complications.
There have recently been attempts to reverse the changes of Barrett esophagus by endoscopically applying ablative therapies.
26) It allows for the detection and biopsy of possible Barrett esophagus (which would not be seen on x-ray studies).
Barrett esophagus is due to GERD and the replacement of squamous epithelium with a specialized columnar epithelium.
Preoperative prevalence of Barrett esophagus in esophageal adenocarcinoma: a systematic review.
9-12) Nongoblet columnar epithelium in the distal esophagus also shows DNA content abnormalities at rates comparable to those of esophageal goblet cells, indicating that esophageal cardiac-type epithelium from patients with Barrett esophagus may already be "intestinalized," despite the absence of morphologic goblet cell differentiation.
Problems related to the evaluation and diagnosis of Barrett esophagus may be the purview of either gastro-enterologists or pathologists.
30) However, the relative contributions of Barrett esophagus and H pylori infection to overall cancer risk are probably unequal: the risk of dysplasia and cancer is highest among patients with long-segment Barrett esophagus, but it is substantially less among patients with either short-segment Barrett esophagus or intestinal metaplasia limited to the cardia.
Srivastava et al (32) evaluated mucosal biopsy samples from 20 patients with Barrett esophagus and 20 patients with intestinal metaplasia of the gastric cardia; they found that intestinal metaplasia subjacent to squamous epithelium, intestinal metaplasia confined to the superficial mucosa, and presence of esophageal glands or ducts were only seen in samples from patients with Barrett esophagus (with sensitivity of 57%, 40%, and 30%, respectively).
In summary, the major points to consider when evaluating nondysplastic mucosal biopsy samples from patients with suspected Barrett esophagus are as follows.