38 PKOFESSOR A. BIRMINGHAM. 



pharynx above commuuicates with the oral pharynx below. For 

 this opening the name i^haryncjeal isthmus (isthmus pharyngo- 

 nasalis of Luschka) is suggested. 



There is practically no part of the constrictors in the wall of 

 the naso-pharynx. The pharyngeal spine lies not on the roof, 

 but low down on the posterior wall of the naso-pharynx ; hence 

 the upper border of the superior constrictor lies just above the 

 level of the pharyngeal isthmus, for which it forms (with the 

 palato-pharyngeus) a kind of sphincter. 



The supra-tonsillar fossa is usually distinct as a variably 

 developed depression just above the tonsil. The plica triangu- 

 laris (His) — a thin triangular fold of mucous membrane, with its 

 base towards the tongue, which projects backwards from the 

 anterior palatine arch over the tonsil, to which it is generally 

 united in the adult — is rarely well marked in the adult or aged 

 body, although so distinct in the child. The crypts of the tonsil 

 communicate freely with one another within its substances (as 

 pointed out by Paterson and others). 



External relations of the tonsil. — The outer surface of the 

 tonsil is enclosed by a distinct fibrous capsule connected with 

 the pharyngeal aponeurosis, outside which lies the superior con- 

 strictor. This latter separates the tonsil in its upper three- 

 fourths from the styloglossus, and in its lower fourth from the 

 stylopharyngeus, with the glosso -pharyngeal nerve winding for- 

 wards over its upper border on its way to the base of the 

 tongue. The ascending palatine artery running upwards and 

 backwards between the styloglossus and stylo- pharyngeus and 

 the tonsillar artery (often a branch of the last) lie in close 

 relation to the outside of the tonsil, separated only by the 

 superior constrictor. The internal carotid, as usually described, 

 lies f to 1 inch behind and to the outer side of the tonsil. 



The (Esophagus. 



Both a diaphragmatic (Jonnesco) and an abdominal part of 

 the oesophagus have been described. The diaphragmatic portion, 

 said to be about half an inch in length (1-5 cm.), corresponds 

 to the portion of the tube which lies in the oesophageal orifice 

 (or canal) of the diaphragm. The long axis of this orifice is 



