1 82 NORMAL HISTOLOGY AND ORGANOGRAPHY. 



opposite the root of the tongue and between the 

 anterior and posterior palatine arches. This lymph- 

 oid tissue is covered with the oral mucous mem- 

 brane, beset with many depressions or pits known 

 as crypts. It is along these crypts that bacteria 

 may enter the tonsil, producing an inflammation of 

 that organ known as tonsillitis. 



Longitudinal muscle 

 layer. 



Fig. 133. Cross section of the esophagus. 



ESOPHAGUS. 



The esophagus is the part of the alimentary canal 

 that intervenes between the pharynx and the stom- 

 ach, and is a very muscular tube about ten inches 

 in length. Its upper end is opposite the lower bor- 

 der of the crycoid cartilage and the sixth cervical 

 vertebra. The lower end or cardiac orifice is oppo- 



