802 THE BASAL GANGLIA OF THE CEREBRUM. 



points suggested by Broca have been marked in Fig. 260, which shows the different 

 parts of the brain according to A. Ecker. K t K 2 K 3 are points in the coronal 

 suture that can be felt through the scalp. K t is placed, in order to avoid the 

 longitudinal sinus, 15 mm. to one side of the median line. K 2 is the point of 

 intersection of the coronal suture and the temporal line. At K 3 the coronal 

 suture intersects the upper margin of the great wing of the sphenoid bone. Lj 

 and L 2 are situated in the lambdoid suture, the former 15 mm. to one side of the 

 highest point, and the latter in the middle of the posterior border of the parietal 

 bone. M corresponds to the highest point of the arch of the squamous suture. 

 If horizontal lines be drawn backward from the points Kj K 2 K 3 , the central fissure 

 C, which is so important in localization, is situated, in the adult, at its upper 

 extremity about 45 mm. and at its lower extremity about 30 mm. behind the 

 coronal suture. According to Merkel the lower extremity is almost 5 cm. verti- 

 cally above the inferior maxillary articulation. The bifurcation of the large 

 fossa of Sylvius is 4 or 5 mm. behind K 3 or, according to Merkel, from 4 to 4.5 cm. 

 above the middle of the malar arch. Its anterior branch is parallel with the 

 coronal suture, and its posterior branch passes through the point M. The parieto- 

 occipital fissure (po) is situated almost exactly in the lambdoid suture or, meas- 

 ured -with compasses, 6 cm. above the external occipital protuberance. The 

 frontal eminence forms the boundary between the first and second temporal con- 

 volutions. The parietal eminence covers the supramarginal gyrus. 



The corpus callosum contains commissural fibers from both hemispheres 

 (according to Mott and Schafer between the two corticomotor centers) , the angular 

 gyri and the occipital and temporal lobes. Division of this structure in the dog 

 causes no appreciable disturbance. In accordance with this fact almost total 

 destruction has been observed in man without the development of noteworthy 

 derangement of motility, coordination, sensibility, reflex activity, the special 

 senses, speech, or considerable impairment of intelligence. The posterior portion 

 of the anterior commissure serves for the connection of the two lingual gyri. 



THE BASAL GANGLIA OF THE CEREBRUM. THE MIDBRAIN. 

 FORCED MOVEMENTS. OTHER CEREBRAL FUNCTIONS. 



The striate body and the lenticular nucleus (Figs. 263, 264) have no 

 direct connection with the cerebral cortex, although fibers pass from 

 their connections to the cerebral peduncle and the medulla oblongata. 

 Their development in the animal kingdom keeps pace with that of the 

 cerebral cortex. The general muscular contractions on the opposite side 

 of the body observed on electrical stimulation are probably due to asso- 

 ciated irritation of adjacent cortico -muscular tracts. 



Gliky observed no movement on irritation of the striate body in the rabbit. 

 It, therefore, appears that the motor tracts in this animal do not traverse the 

 portion of the brain named, but pass by it. 



Destruction of the lenticular nucleus or the striate body gives rise, 

 according to earlier statements, to loss of voluntary movements on the 

 opposite side of the body, with or without preservation of sensibility; 

 although under such circumstances there is also associated injury of the 

 cortico -muscular tracts. Recently, after injuries transitory weakness of 

 the contralateral extremities (loss of muscular sense) has been observed, 

 with increased general irritability and fear, as well as rapid (transitory) 

 elevation of temperature. Irritation of the striate body is unattended 

 with pain. 



Pathological. In man every lesion in the anterior portion of the striate body 

 that is not too small causes contralateral paralysis, which is permanent if the 

 internal capsule is affected, but which may gradually disappear if the lenticular 

 and caudate nuclei are affected. Occasionally vascular dilatation occurs in con- 

 sequence of vasomotor paralysis if the posterior portion is affected, and is attended 

 with redness and slight elevation of temperature in the paralyzed extremities 

 (at least for a time) , swelling (edema) , sweating, alterations in pulse demonstrable 



