80 



LECTURES ON THE CENTRAL NERVOUS SYSTEM. 



External to the corpus striatum lies the cortex of the island 

 of Reil. In the narrow band of white substance which lies be- 

 tween the ganglion and the cortex that is to say, in the exter- 

 nal capsule is placed an elongated collection of ganglion-cells, 

 -the claustrum, which is anatomically somewhat different 

 from the neighboring cortex. 



Cauclad of the nucleus caudatus the horizontal section 

 (Fig. 44) passes through the thalamus, the inter-brain. In 

 front of this the pillars of the fornix ascend from below ; the 



FIG. 47. 



Diagram of the internal capsule. The situation of most of the tracts of fibres which 



compose it is indicated by the names. 



Extremitiiten innt. BnJin, Motor tract to the extremities. 



fasern aus Nucleus Caudatua, Fibres from nucleus caudatns. 



Fuae.rn aus N. lentifttrmis, Fibres from nucleus lentiformis. 



Frontale Briickenhnlin, Anterior cortical tract to the pons. 



Opticwifasern, Optic fibres. Sensorisctie Faaern, Sensory fibres. 



Wnhkranz zum Thalamus, Coronal fibres to the thalamus. 



Temporo-occijritale Brudienbahn, Posterior cortical tract to the pons. 



commissura media, a thin band of gray matter, extends from 

 one thalamus to the other. External to the thalamus passes the 

 posterior branch of the internal capsule. The point where the 

 hyo branches meet is called the knee (genii). Impress this 

 peculiar angular form of the inner capsule well upon your 

 memory. The relation of the different coronal bundles to the 

 two angles is particularly important and very nearly constant. 

 In the posterior branch, not far from the knee, lie the fibres 

 from the motor zone to the extremities (pyramidal tract) ; just 



