CESOPHAGUS. (07w, I carry, and 9wytr, eat.)—Gr. olcrorplvoc; Fr. esophoge ; Ital. gola; Germ. Spciserare. The cesophagus is that portion of the alimentary canal vrhich intervenes between the inferior extremity of the .pharynx and the cardiac orifice of the stomach. It occupies the lower part of the cervical region, traverses the thorax, and enters the abdomen.
Direction.—The direction of the cesophagus is nearly vertical ; in the cervical region it deviates slightly to the left ; in the upper part of the thorax it inclines somewhat to the right, and in the lower part of the same region it is again directed to the left, so as to occupy the median line during. its passage through the diaphragm.
Dimensions.—The cesophagus is not of uni form diameter throughout its entire length. In the neck it is narrower than in any other region ; it consequently happens that a morsel of food too large to pass readily along the cesophagus, is usually arrested immediately after it has been transmitted from the pharynx. In its upper part the cesophagus is somewhat flattened and compressed in the antero-pos terior direction, but its inferior portion is more or less cylindrical, and presents the appearance of a rounded cord.
Relations.—The cesophagus has many im portant relations, which may be considered successively in the cervical, thomcic, and ab dominal regions. In the cervical region it corresponds anteriorly to the membranous part of the trachea, with which it is connected by some intervening cellular tissue : in the lower part of the neck where it deviates to the left it comes in contact anteriorly with the left sterno-thyroid muscle, the thyroid gland, the inferior thyroid artery, and the left recurrent nerve. Posteriorly it has the cervical vertebrx and the longus colli muscle, with which it is connected by means of loose cellular tissue, so that free movement of the cesophagus upon the spine is allowed during the process of deglutition. Laterally it is in relation with the thyroid body, with the common carotid arteries, and more externally with the vagi nerves and the internal jugular veins: In consequence of the cesophagus deviating slightly to the left in the lower part of the neck, its relations are somewhat different on the two sides. Thus the
left common carotid is in closer relation with the cesophagus than the right. The left recur rent nerve is anterior to the cesophagus, while the right is somewhat posterior.
The thoracic portion of the cesophagus is placed in the posterior mediastinum. It cor responds anteriorly to the tmchea, and imme diately below the bifurcation of the trachea to the left bronchus, which crosses it obliquely, to the arch of the aorta, to the left subclavian and carotid arteries, and to the base of the heart, from which it is separated by the pericardium. Posteriorly it has the spine, with which in the upper part of the chest it is in close contact ; but as it descends it becomes separated from the spine by cellular membrane, by the right intercostal arteries, by the vena azygos, and by the thoracic duct, which in the lower part of the chest is on the right of the cesophagus, but ascending it passes behind and above is placed on its left side. At the inferior part of the thorax, immediately before passing through the diaphragm, the cesophagus has behind it the thoracic aorta. Laterally it has on its left the aorta, and on the right side the pleum forming the right layer of the posterior mediastinum. It is accompanied by the two vagi nerves, one on each side, which send numerous filaments from one to the other, and thus form the plexus gulm ; at the lower part of the chest the left vagus nerve becomes somewhat anterior, and the right posterior. This portion of the cesophagus is surrounded by a considerable quantity of loose cellular tissue and by severa lymphatic glands.
The abdominal portion of the cesophagus very short, and has no relations of importanc: After passing through the diaphragm it is vered both anteriorly and posteriorly by th peritoneum. It also comes into contact ant riorly with the left lobe of the liver. Witho depressing the stomach and elevating the chi phragrn this portion of the cesophag-us cam], be seen, and, in fact, can scarcely be said t exist.