DIVEETICULA OF THE (ESOPHAGUS. 349 



point of the knife is plunged almost directly outwards. The 

 vessel which in point of fact lies closest to the tonsil is the main 

 trunk of the facial artery, and in cases where external pressure 

 is applied just below the angle of the mandible, to push the 

 tonsil inwards during the operation of tonsillotomy or ton- 

 sillectomy, this artery may possibly be in some degree of danger. 

 The actual vessels from which blood flows after tonsillotomy are 

 the tonsillar branches of the ascending pharyngeal, of the facial, 

 of the dorsalis linguae, and sometimes branches from the internal 

 maxillary. 



In order to engage the tonsil satisfactorily in the ring of a 

 guillotine, it is well to remember that the front portion of the 

 organ is overlapped to a certain extent by the anterior pillar of 

 the fauces, containing the palato-glossus muscle, and therefore 

 the posterior portion of the tonsil should be first caught by the 

 instrument. 



DISEASES OF THE (ESOPHAGUS. 



Malformations and Diverticula of the (Esophagus. A com- 

 plete interruption of the oesophagus a short distance above the 

 bifurcation of the trachea may be met with. The upper end of 

 its lower segment then opens into the trachea. This malforma- 

 tion does not, as was once supposed, indicate a failure of the 

 buccal invagination of epiblast to fuse with the fore-gut, but is 

 probably due to obliteration of part of the gullet by traction of 

 the outgrowing lung bud, which springs from the alimentary 

 tract in this situation. Congenital strictures may occur in the 

 same situation and are due to the same cause. 



Pressure pouches occur in the mid-line posteriorly at the junc- 

 tion of the oesophagus and pharynx. These diver ticula are at 

 first lodged in the retro-pharyngeal space but later present them- 

 selves at the left side of the neck. The part of the oesophagus 

 from which ihey arise is weakened owing to the divergence of 

 the longitudinal muscular fibres towards the front in the form 

 of two lateral bands which become attached to the back of the 

 cricoid cartilage. Although known as pressure pouches of the 



