786 



NEUROLOGY 



projection of the superficial transverse fibers, and thus give rise to the eminences 

 on the anterior surface. Some of these fibers end in, or give off collateral to, the; 

 nuclei pontis. An important pathway is thus formed between the cerebral cortex 

 and the cerebellum, the first neuron having its cell body in the cortex and sending 

 its axon through the internal capsule and cerebral peduncle to form synapses either 

 by terminals or collaterals with cell bodies situated in the nuclei pontis. Axons 

 from these cells form the transverse fibers which pass through the middle peduncle 

 into the cerebellum. Others after decussating, terminate either directly or indi- 

 rectly in the motor nuclei of the trigeminal, abducent, facial, and hypoglossal 

 nerves; but most of them are carried through the pons, and at its lower surface 

 are collected into the pyramids of the medulla. The fibers which end in the motor 

 nuclei of the cranial nerves are derived from the cells of the cerebral cortex, and 

 bear the same relation to the motor cells of the cranial nerves that the cerebro- 



Ant. med, 

 velum 



Superior peduncle 



Mesencephalic root V. 

 Nn. mes. root 



Med. long, fas 



Lateral lemniscus 



Formatio reticularis-j, 



Fourth ventricle 



Medial 

 lemniscus 



Transverse 

 fibers 



Cerebrospinal 

 fasciculi 



Trigemi 



Rapfie 

 FIG. 701. Coronal section of the pons, at its upper part. 



spinal fibers bear to the motor cells in the anterior column of the medulla spinalis. 

 Probably none of the collaterals or terminals of the cerebrospinal and cerebro- 

 bulbar fibers end directly in the motor nuclei of the spinal and cranial nerves, one or 

 more association neurons are probably interpolated in the pathway. 



The nuclei pontis are serially continuous with the arcuate nuclei in the medulla, 

 and consist of small groups of multipolar nerve cells which are scattered between 

 the bundles of transverse fibers. 



The dorsal or tegmental part of the pons is chiefly composed of an upward con- 

 tinuation of the reticular formation and gray substance of the medulla oblongata. 

 It consists of transverse and longitudinal fibers and also contains important gray 

 nuclei, and is subdivided by a median raphe, which, however, does not extend into 

 the basilar part, being obliterated by the transverse fibers. The transverse fibers 

 in the lower part of the pons are collected into a distinct strand, named the 



