174 NORMAL HISTOLOGY AND ORGANOGRAPHY. 



description the tongue may be divided into body, 

 base, inferior surface, and dorsum. 



Body. This is chiefly made up of striped muscle 

 which may be divided into intrinsic and extrinsic. 

 A median septum divides it into two symmetrical 

 lateral halves. Connective -tissue elements, nerves, 

 the body of glands, and blood-vessels interlace 

 freely with the muscle. The musculature is best 

 studied in a beef's tongue that has been boiled, and 

 is a subject that belongs to gross anatomy. In any 

 section of the tongue, muscle fibers will be seen both 

 in cross section and in longitudinal section. 



Base. This is the posterior wide end of the tongue 

 that is attached to the hyoid bone. It is covered 

 with a smooth mucous membrane, beneath which is 

 a rich supply of lymphoid tissue. The latter con- 

 stitutes the lingual tonsil. Mucous glands are abun- 

 dant. 



Inferior Surface. This is covered with smooth 

 mucous membrane on which open many mucous and 

 serous glands. The surface is divided into two 

 halves by a fibrous septum which passes to the floor 

 of the mouth and is known as the lingual frenum. 

 When this is abnormally short the person is said to be 

 tongue-tied, and speech is impaired. 



The Dorsum. This surface is convex both from 

 before backward and from side to side. A median 

 depression, or sulcus, divides it into lateral halves. 

 The sulcus apex points backward to the foramen 

 cecum just in front of the base. This cecum is a 

 blind pocket that marks the origin of the middle 

 portion of the thyroid gland, and is the remnant of 



