NERVUS ACCESSOR1US. 469 



ceed downwards and backwards, two filaments, which join the 

 phrenic nerve; also, one to the lower part of the omo-hyoid 

 muscle ; and three or more, which are divided and distributed 

 upon the sterno-hyoid and thyroid muscles, and upon the mus- 

 cles of the larynx. Meckel states, that some of these ramifica- 

 tions, on the left side principally, penetrate to the thorax, and 

 reach the pericardium. 



The hypoglossal nerve, having sent off the ramus descend- 

 ens, reaches the external face of the hyo-glossus muscle, and is 

 there concealed by the mylo-hyoideus, where it gives filaments 

 to the muscles of the larynx, to the hyp-glossus, genio-hyoideus, 

 and genio-hyo-glossus. These filaments anastomose frequently 

 with e<ach other, and in two or three places at the anterior part 

 of the tongue with the lingual branch of the nervus trigeminus. 

 After these branches are given off, the trunk of the hypo-glossal 

 nerve penetrates into the substance of the genio-hyo-glossus 

 muscle, and extends itself near its fellow, and not far from the 

 middle line of the tongue to tKe point of the latter. It first dis- 

 tributes filaments near the posterior part of the tongue, and 

 then, successively, as far as its anterior extremity. They can- 

 not be traced to the papilla, but are lost upon the muscular 

 structure. 



It is a general opinion among anatomists that the hypo-glos- 

 sal nerve is only intended to excite the muscular movements 

 of the tongue. The opinion is founded upon the circumstance 

 of its filaments not reaching the papillae, whereas those of the 

 lingual branch of the trigeminus do. Colombo narrates a case, 

 in which there was a congenital privation of taste, where the 

 lingual branch of the trigeminus was distributed upon the occi- 

 put instead of upon the tongue, which goes far to prove the dif- 

 ference of function in the two nerves. 



SECT. IX. NERVUS ACCESSORIUS. 



The Accessory Nerve, (Nervv-s Accessorins, Willisii,) having 

 arisen, as described from the cervical medulla and the medulla 

 oblongata, is directed, outwards to the posterior foramen lace- 

 rum, in company with the pneumogastric or par vagum. Some- 

 times it is separated from it in its passage through the base of 



VOL. II. 41 



