264 THE RHOMBENCEPHALON. 



the fourth ventricle between the brachia conjunctiva. It is 

 composed of longitudinal and transverse fibers. One distinct 

 bundle, derived from the spinal cord, passes through it to the worm. 

 This is the anterior ascending cerebello-spinal tract (Hoche). 

 The decussating root-fibers of the fourth nerve (trochlear) course 

 transversely through it and also the commissural fibers between 

 Bechterew's nuclei. 



Brachium Pontis (Middle Peduncle, Figs. 44, 78, 81 and 91). 

 The brachium pontis comes from the pons, of which it forms the 

 anterior and middle transverse fibers. It enters into the med- 

 ullary body of the cerebellum lateral to both the brachium con- 

 junctivum and the restiform body. According to Klimoff fibers 

 running to the cerebellum make up the entire brachium pontis. 

 These are axones of the nucleus pontis, chiefly the opposite one. 

 Most of them run to the cortex of the cerebellar hemisphere; a 

 small number runs to the vermis cerebelli. They form a seg- 

 ment in the indirect motor path contained, above the pons, in 

 the medial and lateral fifths and the intermediate bundle of the 

 basis pedunculi. In the cerebellar end of the brachium pontis 

 we may include the acustico-cerebellar tract. The latter is largely 

 a descending tract but may contain some ascending vestibular 

 fibers. It rises hi the cerebellar nuclei, and probably in the gan- 

 glionar layer of the cortex; it terminates in the nucleus of Deiters. 

 The principle origin of the acustico-cerebellar tract is in the oppo- 

 site nucleus fastigii and nucleus globosus. It forms a part of the 

 descending limb of the arc of equilibrium. By far the greater 

 number of fibers in the brachium pontis, whether efferent or affer- 

 ent, are crossed fibers. 



Possibly there are in the brachium pontis axones of Purkinje's cells which 

 terminate in the nuclei pontis on both sides and in the nuclei of the reticular 

 formation. 



The corpus restiforme (inferior peduncle) (Figs. 44, 78, 81 

 and 91) can be traced both to and from the upper part of the 

 hemisphere and worm. Inferiorly, it is the restiform body of 

 the medulla oblongata. The bundles of component fibers are 

 very numerous: (i) The posterior cerebello-spinal fasciculus (direct 

 cerebellar tract), whose origin is in the dorsal nucleus of the cord 



