30 THE (ESOPHAGUS. 



The muscular coat of the oesophagus is next in thickness to 

 that of the pharynx, and thicker than that of any other portion 

 of the alimentary canal. 



The internal coat of the oesophagus, resembling that of the 

 fauces, is soft and spongy. It is covered with a very delicate 

 cuticle, which Haller supposed to be too tender to confine the 

 matter of variolous pustules, as he had never found these 

 extending into the oesophagus. It is very vascular, and abounds 

 with the orifices of mucous follicles, from which is constantly 

 poured out the mucus that is spread over this surface. When 

 the oesophagus is not distended, many longitudinal plaits are 

 found in this membrane by the contraction of the circular or 

 transverse fibres exterior to it. These plaits are calculated to 

 admit readily of the distension which is requisite in deglutition. 

 This tunic is continued from the lining membrane of the pha- 

 rynx above, and terminates below in the villous coat of the 

 stomach ; from which, however, it is very different. 



The cuticle terminates by an irregularly fringed or fes- 

 tooned border at the cardiac orifice, where the oesophagus ter- 

 minates, and is insensibly lost upon the mucous membrane of 

 the stomach. The mucous membrane of the oesophagus, like 

 that of the rectum (and unlike that of any other portion of the 

 alimentary canal,) is united by a very loose cellular tissue to 

 the inner face of the circular stratum of fibres, so that it may 

 be withdrawn as a cylindrical tube from the muscular sheath in 

 which it is contained. 



Experimenters upon living animals have asserted that they 

 have seen the muscular coat, force by its contraction the mu- 

 cous membrane downwards into the stomach, so as to cause it to 

 form a circular tumor, much like that of the mucous membrane 

 of the rectum in prolapsus ani. 



The blood-vessels of the oesophagus come from the aorta 

 and those which are in the vicinity. The nerves are derived 

 from the eighth pair. The lymphatic vessels are very abun- 

 dant. 



In the neck the oesophagus inclines rather to the left of the 

 middle line. As it proceeds down the back between the lamina 



