CONDUCTION IN THE MEDULLA OBLONGATA. 



889 



In the guinea-pig the pyramid path crosses into the dorsal column of the cord. 

 The excitation of each pyramid evokes movements chiefly in the contralateral 

 skeletal muscles, especially of the limbs, but to some extent also in the 

 homonymous. 1 Complete severance of both the pyramids does not, however, 

 produce even in so high a type as the dog any obvious permanent paralysis of 

 movement,- nor does it prevent in the dog excitation of the Rolandic cortex, 

 producing movement both on the crossed or uncrossed limbs. 3 The pyramidal 

 paths decussate in major part at the caudal end of the bulb. The decussation, 

 when examined by excitation, extends over a longer 4 area than anatomical 



c.r 



ar//?t. 



Fig. 361. — Transverse section of the medulla oblongata somewhat above the 

 middle of the olivary body, p.l.b, posterior longitudinal bundle ; n.t, 

 nucleus of funiculus teres ; n.XII, nucleus hypoglossi ; n.X, nucleus vagi ; 

 n'X. nucleus ambiguus ; s, fasciculus solitarius ; n.p, nucleus posterior 

 (cuneatus) ; f.r, formatio reticularis; t, trenia ; s.B, substantia Rolandi ; 

 a. V, ascending root of fifth ; c.r, corpus restiforme ; ar.int, internal arcuate 

 fibres ; X, issuing root of vagus ; n.l, nucleus lateralis ; n' , groups of large 

 cells, perhaps belonging to nucleus lateralis ; a-l.tr, antero-lateral ascending 

 tract ; n.d.o, nucleus dentatus oliva? ; acc.o, accessory olivary nucleus ; s.o, 

 siliqua oliva? ; h.o, hilum olivre ; p, pyramid ;/, fillet ; r, raphe ; n.ar, nucleus 

 of arcuate fibres ; ar.ext, external arcuate fibres. — Schafer (from a photo- 

 graph). Magnified 5 diameters. 



examination would lead one to suspect. Pyramidal fibres have been traced 5 into 

 the hypoglossal nucleus, but not into the other motor nuclei of this region, and 

 only into the contralateral hypoglossal. By some 6 a descending spino-cerebellar 



1 Wertheinier and Lepage, Arch, de physiol. norm, et path., Paris, 1897, tome ix. p. 163. 



2 Starlinger, Neurol. Centralbl., Leipzig, 1895, Bd. xiv. S. 390, and of. various papers 

 from Goltz's laboratory. 



3 Wertheinier and Lepage, Arch, dc physiol. norm, et path., Paris, 1896, tome viii. 



4 Balighian, Bcitr. z. Anat. u. Physiol. {Eckhard), Giessen, 1879, Bd. viii. ; Stall'any, 

 ibid., 1888, Bd. xii. ; Wertheinier and Lepage, Arch, de })hysiol. norm, et j>ath., Paris, 

 1897, tome ix. p. 168. 



5 Ronianow, Neurol. Cen/ralbl., Leipzig, 1898, Bd. xvii. S. 593. 



6 Biedl, ibid., 1895, Bd. xiv. ; A. Thomas, "II cerveletto," Florence, 1897. This is in 

 accord with the original statement by Marchi, 1888. 



