THE MEDIASTINUM. 



angle between the innominate and left carotid arteries. The esophagus runs behind the trachea 

 and is displaced somewhat to the left (Fig. 54). 



The angle of the tracheal bifurcation is filled by a varying number (twenty to thirty) of 

 lymphatic glands which follow the bronchi as far as the hilus of the lung and are usually markedly 

 pigmented. They frequently become diseased (particularly in tuberculosis), producing swellings, 

 unusually firm adhesions, and perforation with the escape of pus into the trachea and the bronchi 

 (Fig. 54). Some of these same lymphatic glands are in relation anteriorly with the posterior 

 portion of the pericardium which is not covered by the mediastinal pleura, and their diseases 

 may consequently extend to the pericardium. These lymphatic glands are also of practical 

 importance on account of their relation to the esophagus (see below, Plate 8, and Fig. 54). 



The trachea is more or less movable in the loose connective tissue of the mediastinum, 

 although its walls are rather rigid from the presence of the tracheal rings. It may be pushed 

 to one side by mediastinal tumors, or even absolutely occluded, particularly when the tumor 

 compresses the trachea against the vertebral column. 



The Esophagus [lies partly in the neck, partly in the thorax; in the neck it begins at the 

 level of the cricoid cartilage in front of the sixth cervical vertebra. ED.]. Upon entering the 

 thorax the esophagus is behind and somewhat to the left of the trachea (Plates 10 and n, and 

 Fig. 54) and is attached to the vertebral column by loose connective tissue. The esophagus 

 crosses the tracheal bifurcation behind the origin of the left bronchus, in which position it is 

 situated to the right side of the aorta where the aortic arch ends and the thoracic aorta com- 

 mences. It descends along the right side of the aorta, covered by the right mediastinal pleura, 

 passes in front of the aorta, and, after going through the esophageal opening (in front and some- 

 what to the left of the aortic opening), ends in the cardiac extremity of the stomach three centi- 

 meters below the diaphragm (see Fig. 54). The esophagus may consequently be exposed 

 within the mediastinum from the right pleural cavity above and from the left pleural cavity below; 

 in the latter situation it is in front of the aorta. This is also the portion of the esophagus which 

 is covered anteriorly by the pericardium (Fig. 51). 



The esophagus possesses three narrow portions: (i) At the cricoid cartilage, in the neck, 

 where the contraction of the inferior constrictor of the pharynx may offer a definite resistance 

 to the passage of a sound; (2) at the level of the tracheal bifurcation; (3) at the esophageal open- 

 ing in the diaphragm. The first narrowing is about 15 centimeters from the incisor teeth; at 

 the second narrow portion, which is about 25 centimeters from the incisor teeth, the esophagus 

 is in relation anteriorly with numerous lymphatic glands (bronchial glands, see Fig. 54). The 

 distance between the third narrowing and the incisor teeth is about 40 centimeters, and it is 

 most frequently the seat of stricture (in carcinoma of the cardia). In addition to these con- 

 strictions, there are others which have recently claimed the attention of anatomists, but it remains 

 to be seen whether they are of any practical importance. [The average length of the esophagus 

 in the adult is 10 inches (25 centimeters); the distance from the incisor teeth to its commence- 

 ment is 6 inches; to the point or level where it is crossed by the left bronchus, 9 inches; to the 

 esophageal opening of the diaphragm, 14 to 15 inches; to the cardiac orifice of the stomach, 16 

 inches. Stiles, in Cunningham's "Anatomy."] 



Foreign bodies which have entered the esophagus or pharyngeal ulcerations (carcinoma) 



