(ESOPHAGUS. 507 



The shape of the cavity of the pharynx is oblong and cylin- 

 drical, being somewhat larger at its superior end] at the latter 

 place, where it is attached to the petrous bone, it presents a 

 deep corner, which gives it a square appearance there, and has 

 a collection of muciparous follicles somewhat like the tonsil 

 gland. Anteriorly, and above, it is continuous with the Eusta- 

 chian tubes, and with the posterior nares; just below this, with 

 the fauces and mouth, and below the root of the tongue with 

 the cavity of the glottis or larynx. At its lower extremity, 

 where it terminates in the oesophagus, it is so contracted as to 

 suit the size of the latter cavity. 



SECT. II. OP THE (ESOPHAGUS. 



The ossophagus is the tube just i-n front of the spine and be- 

 hind the trachea, which conducts food from the pharynx into 

 the stomach. When inflated it is of a cylindrical shape, about 

 ten or twelve lines in diameter : it is nine or ten inches long, 

 and gradually increases in its size from above downwards: in 

 its state of repose it is flattened from before backwards. Its 

 descent is not entirely vertical, but at the lower part of the 

 neck it inclines somewhat to the left of the middle line, and is, 

 therefore, rather to the left side of the trachea than behind it. 

 It passes down the thorax in the posterior mediastinum, being 

 bounded on its left side by the aorta, and on the right by the 

 vena azygos. It keeps during the early part of its course in 

 this cavity, in front of the middle line of the spine; but lower 

 down it inclines again slightly to the left side, in front of the 

 aorta, in order to reach the cesophageal orifice of the diaphragm, 

 through which it penetrates into the abdomen. In all this pas- 

 sage the oesophagus is united to adjacent parts by a loose cel- 

 lular tissue. 



The oesophagus is composed of three coats: the muscular; 

 the cellular or nervous; and the mucous. 



The muscular coat is the external, and very strong. It con- 

 sists in two well marked lamina? of muscular fibres. The most 

 exterior is the thickest, and goes, longitudinally, from one end 

 to the other of the tube; commencing, according to J. F. 

 Meckel, by three fasciculi above; one of which arises, tendi- 



