120 Neurological Technique 



V. N. Trigeminus, the largest of the nervi cerebrales, enters 

 the pons on its lateral aspect, passing through the anterior 

 portion of the brachium pontis. Note that it has two roots, 

 a smaller motor (portio minor) and a large sensory root (portio 

 major). The fibers of the portio major have their origin in the 

 large ganglion semilunare (Gasserian ganglion), which, in the 

 removal of the brain, was left in its position at the base of the 

 cranium (impressio trigemini of the os temporale). 



VI. N. Abducens, leaves the medulla oblongata nearer the 

 middle line and just under the posterior border of the pons. 



VII. N. Facialis, leaves the medulla from its lateral aspect, 

 at about the same level as the abducens. Occasionally a portion 

 of the N. facialis (N. intermedius) passes through the posterior 

 border of the pons. 



VIII. N. Acusticus, enters the medulla on its extreme lateral 

 aspect, a part of it passing around the corpus restiforme to the 

 dorsal aspect. It has two roots, radix cochlearis and radix 

 vestibularis. 



IX. N. Glossopharyngeus, also enters the medulla on its 

 lateral aspect and between the oliva and corpus restiforme. 



X. N. Vagus, larger than the glossopharyngeus, and enters 

 the medulla in the same line and so near to the glossopharyn- 

 geus as to often make the two appear as the fila of one nerve. 



XI. Accessorius, arises from the medulla oblongata and the 

 adjoining portion of the medulla spinalis by a series of rootlets. 

 These join to form the common trunk which runs parallel to the 

 medulla oblongata up to the level of the vagus, where it turns 

 outward parallel with that nerve. 



XII. N. Hypoglossus, arises nearer the mid-line. It also is 

 formed by a series of rootlets (fila radicularia) which leave the 

 medulla oblongata between the oliva and pyramis. In its 

 origin it closely resembles the motor root (radix anterior) of a 

 spinal nerve. 



Observe that, exclusive of the 1st and Ild, the nervi 

 cerebrales enter or leave the encephalon along two parallel lines, 

 a lateral line and a ventro-lateral line. The Illd, Vlth, and 



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