470 NERVOUS SYSTEM. 



the cranium, by a thin partition of dura mater; on other occa- 

 sions merely by a fold of the tunica arachnoidea: but at the in- 

 ferior part of this foramen it adheres so closely to the par va- 

 gum that the two look like but one nerve. 



Near its exit it is divided into two fasciculi. The internal 

 gives off one or two filaments, which, joining a branch of the 

 par vagum, forms the superior pharyngeal nerve; the internal 

 branch then descends, and bing divided into several branches, 

 they, successively, join the upper part of the par vagum. The 

 external fasciculus descends for two inches behind the internal 

 jugular vein, being placed first of all between it and the occipi- 

 tal artery, but subsequently between the vein and the sterno- 

 mastoid muscle. It then pierces this muscle about one-third of 

 the length of the latter from its superior extremity, and leaves 

 filaments in it which anastomose with some from the third cer- 

 vical nerve. In continuing its descent, it is re-enforced and 

 augmented considerably in volume, by branches from the second 

 and third cervical. Having reached the anterior margin of the 

 trapezius muscle, it then distributes itself to the latter, by inter- 

 nal and by external branches. 



SECT. X. NERVUS GLOSSO-PHARYNGEUS. 



The Glosso-Pharyngeal Nerve (Nervus Glosso-Pharyngeus,) 

 though commonly considered as distinct from the pneumogas- 

 tric, has so many connexions with it, both at its root, in its 

 course through the posterior foramen lacerum, and in its dis- 

 tribution, that it seems like a part or branch of the same. At 

 the base of the cranium in front of the pneumogastric, it forms, 

 according to some anatomists,* a ganglion of five or six lines 

 in length, the existence of which was denied by Bichat. From 

 this ganglion proceeds a filament,f which penetrates into the 

 tympanum and divides into two branches; one of them ascends 

 along the promontory, having detached a filament to the mem- 

 brane of the foramen rotundum: it then penetrates the petrous 



* Andersach and Huber. This ganglion is considered by some as commencing 

 before the nerve penetrates the foramen lacerum. 

 f Rosenmuller, Jacobson, Lobstein. 



