THE TONGUE 353 



where it disappears under cover of the hyo-glossus muscle. 

 There it divides into two branches. The smaller of the two 

 extends forwards, upon the side of the tongue, and may be 

 traced as far as a point midway between the root and the tip. 

 The larger branch turns upwards, and is distributed to the 

 mucous membrane which invests the posterior third of the 

 dorsum linguae. It gives twigs to the vallate papillae, and 

 some fine filaments may be followed to the anterior surface 

 of the epiglottis. The glosso-pharyngeal nerve is a nerve of 

 taste and of common sensibility. 



The lingual and hypoglossal nerves are described on pages 

 182 and 196, and their terminal branches should now be 

 traced as far as is possible. 



The internal laryngeal nerve gives a few delicate filaments 

 to the glosso-epiglottic and pharyngo-epiglottic folds and the 

 mucous membrane of the pharyngeal aspect of the tongue. 



The arteria profunda linguae, should be followed to the tip 

 of the tongue, where it forms a small loop of anastomosis with 

 its fellow of the opposite side. 



Septum Linguae. The septum of the tongue can be seen 

 best in a transverse section through the organ. Such a 

 section will also display, in a measure, the transverse and 

 vertical muscular fibres. The septum is a median fibrous 

 partition. It is strongest posteriorly, where it is attached 

 to the hyoid bone. It does not reach the dorsum of the 

 tongue, being separated from it by the superior longitudinal 

 muscle. 



ENCEPHALON THE BRAIN. 



BEFORE the dissector commences the dissections of the brain 

 he must be familiar with its main features and with the 

 general arrangement of its parts. For this purpose he should 

 obtain the half of a brain which has been divided by a 

 median sagittal section, and from which the membranes have 

 been removed, or a cast of such a specimen, and examine it 

 from both its medial and its lateral sides (see Figs. 135, 136). 



The brain is that portion of the central nervous system 

 which lies in the cranial cavity, where it is surrounded by 

 three membranes, the dura mater, which has already been 

 examined (p. 99), and the arachnoid and the pia mater, which 



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