PROJECTION FIBERS. 231 



the peduncle the hip fibers are medial and the toe fibers lateral. 

 Fibers which innervate the muscles of the thigh, leg and small 

 toes have this same relative position and order between the hip 

 and great toe fibers both in their cortical origin and in their course 

 through the internal capsule and basis pedunculi. 



There are other corticifugal fibers in the internal capsule, viz., 

 some within the occipito-thalamic and temporo-thalamic radia- 

 tions (Figs. 70 and 71) and others running from the special and 

 common sensory areas of the cortex; but these fibers are prob- 

 ably reflex- in function and do not properly belong to the pro- 

 jection group. 



Several bundles of descending fibers are found in the tegmentum, 

 namely, the anterior longitudinal bundle, which is reflex in func- 

 tion, the rubro-spinal tract from the red nucleus, a small part 

 of the brachium conjunctivum of the cerebellum, the descending 

 root of the trigeminal nerve, the olivary bundle, and certain other 

 fibers in the formatio reticularis. With these exceptions the 

 tegmentum is ascending in direction and sensory in function. 



Destruction by clot or tumor, or otherwise, of any of the above 

 divisions of the pyramidal tract causes upper segment paralysis 

 of the particular muscles innervated through that tract, the muscles 

 being spastic and the reflexes increased. 



SENSORY OR CORTICIPETAL PROJECTION FIBERS. 



The sensory or corticipetal projection fibers of the tegmentum 

 comprise the medial, superior and lateral fillets; the- spino-thala- 

 mic tract; the brachium conjunctivum of the cerebellum; a part 

 of the medial longitudinal bundle; and certain other ascending 

 fibers of the formatio reticularis. Excepting a small number 

 of fibers, all these bundles terminate in the basal ganglia; but 

 the paths of conduction are continued through the internal cap- 

 sule. The medial fillet carries impressions of the tactile and the 

 muscular senses; the spino-thalamic tract conducts tactile, pain 

 and temperature impulses; while all varieties of common sensory 

 impulses are carried by the brachium conjunctivum cerebelli. 

 Chiefly through these three tracts, common sensory impressions 



