602 



THE NERVOUS SYSTEM 



sules, and pass down to the crus. In the internal capsule the fibers which 

 pass to the pyramidal tracts of the spinal cord occupy that part known as 

 the knee (genu) and the anterior two-thirds of the posterior limbs of the cap- 

 sule, figure 404. In this district the fibers for the face, arm, and leg are in 

 this relation: those for the face and tongue are just at the knee, and below or 

 behind them come first the fibers for the arm and then those for the leg. 



CALIOSUM 



TEMPORO-PONTINE 

 TRACT 



LOBt 



FIG. 403. Diagram of Certain Connections of the Frontal, Temporal, and Occipital 

 Lobes. Founded on the observations of Flechsig, Ferrier, and Turner. (Cunningham.) 



The more accurately known arrangements of these fibers in the monkey's 

 brain, named in order, from above down, are those for the eye, head, tongue, 

 mouth, shoulder, elbow, digits, abdomen, hip, knee, digits. These fibers 

 come for the most part from the portion of the cortex in front of the fissure of 

 Rolando, chiefly from the precentral gyrus, hence called the Rolandic area. 

 Those fibers, passing between the occipital lobe and the thalamus and 

 superior corpora quadrigemina, are concerned with vision, and are called 

 fibers of the optic radiation. In like manner, from the inferior corpora 

 quadrigemina and the internal geniculate bodies, fibers which make up the 

 auditory radiation pass to the auditory center in the superior temporal gyrus. 



