350 CLINICAL APPLIED ANATOMY. 



oesophagus it is possible that some of these diverticula really arise 

 in the pharynx and are due to defective closure of pharyngeal 

 clefts. 



Traction diverticula are usually found on the anterior wall of 

 the oesophagus, near the tracheal bifurcation. They are 

 attributed to the contraction of inflamed and adherent bronchial 

 glands. Inflammatory adhesion of the oesophagus to the right 

 lung has been known to have the same effect. (Esophageal 

 diverticula are prone to ulceration, and thus communications 

 may be established between the oesophagus on the one hand and 

 the trachea, bronchi, pleura, pericardium or mediastinal spaces 

 on the other. 



A perioesophageal abscess lies in the surrounding mediastinal 

 tissue which is continuous above with the retropharyngeal space. 

 The abscess may arise in connexion with caries of the vertebrae, 

 suppurating lymph glands or inflammations and perforations of 

 the oesophagus itself. The natural tendency of the abscess is 

 to open into the oesophagus or pharynx, but it sometimes 

 perforates the trachea or may be guided by the connective tissue 

 planes towards the contiguous pleural sacs. The mediastinal 

 abscess of caries often presents posteriorly, following the con- 

 nective tissue sheaths of the posterior branches of the intercostal 

 arteries. These sheaths are continuous with the mediastinal 

 tissues surrounding the aorta. Eetropharyngeal abscesses some- 

 times track through the thorax into the abdomen. By pressure 

 of mediastinal abscesses on the vagus or air tubes a dangerous 

 form of paroxysmal dyspnoea may be induced. 



There are three places where the oesophagus is somewhat 

 constricted and at which malignant disease is most likely to 

 commence. The first place is quite at the commencement, oppo- 

 site the cricoid cartilage and six inches from the incisor teeth. 

 The second place is supposed to indicate the level at which the 

 lung bud originally arose from the gullet ; it is a short distance 

 above the point where the left bronchus crosses the latter and 

 lies about nine inches from the incisors. The third constriction 

 is at the oesophageal opening of the diaphragm, at least fifteen 



