PHYSIOLOGICAL TOPOGRAPHY OF SURFACE OF CEREBRUM. 



793 



of the medulla (Fig. 261), and thence in the pyramidal tracts of the 

 spinal cord. It is obvious that lesions of these tracts at any point in 

 their course must have the same effect, namely hemiplegia. In the 

 progress of the degenerative process the paralyzed muscles may exhibit a 

 certain degree of spastic rigidity and an increase of irritability to mechan- 

 ical stimulation (tendon-reflexes), which must be considered as an irrita- 

 tive degeneration phenomenon. Later on, degenerative changes are ob- 

 served in the ganglion-cells of the anterior horn and in consequence of 

 these, atrophy and disappearance of the related muscles. 



cm 



02 



FIG. 260. The Cerebrum with the Principal Convolutions and Sulci (after A. Ecker) in its Longitudinal Rela- 

 tion to the Skull: S, the Sylvian fissure, with its vertical ascending short anterior limb and its horizontal pos- 

 terior longer limb; C, the central fissure or sulcus, or fissure of Rolando; A anterior, B posterior central 

 convolution ; Fj superior, F 2 middle, F 3 inferior frontal convolution; f i superior, f 2 middle, f 3 vertical 

 frontal fissure (precentral sulcus); P,, superior parietal lobule; P 2 , inferior parietal lobule, with P 2 indicating 

 the supramarginal gyrus and P.., 1 angular gyrus; ip, interparietal" sulcus; cm, extremity of the callosomargi- 

 nal sulcus; O t first, O 2 second, O 3 third occipital convolution; po, parieto-occipital fissure; o, transverse 

 occipital sulcus; o 2 , inferior longitudinal sulcus; T, first, T 2 second, T 3 third temporal convolution; t t first, 

 t 2 second temporal fissure; K lf K 2 , K s , points in the sagittal suture; L,, L 2 , points in the lambdoid suture. 



The muscular atrophy is not always proportionate to the intensity of the 

 paralysis. Perhaps special trophic fibers, separated from the motor fibers, and 

 situated nearer the sensory fibers, pass from the cerebrum downward through 

 the internal capsule. The tract for the seventh, eleventh, and twelfth cerebral 

 nerves is situated in the genu of the internal capsule. The tracts for the rotation 

 of the eyes, the muscles of the trunk and the nape of the neck are situated on either 

 side in the internal capsule for both sides of the body. 



According to observations of Flechsig and Hoesel it appears that the motor 

 area is at the same time the sensory center for the muscle-sense and innervational 



