Fig. 7. Arrangement of Fibres in the Internal Capsule. 



All the fibres from one hemisphere pass together through the Cms at the 

 Base of the Brain. In their course from the Cortex to the Crus these fibres pass 

 between the large Basal Ganglia (Thalamic, Caudate and Lenticular Nuclei), as 

 shewn in the figure. Leaving the outermost and external capsules out of con- 

 sideration these fibres have but one course open to them, viz : between the Caudate 

 and Lenticular Nuclei and between the Thalamic and Lenticular Nuclei. This is 

 the Internal Capsule with its Anterior and Posterior limbs and an intervening bend 

 (genu). The arrangement of the fibres in the Internal Capsule is as follows: — 

 The pyramidal tract, the path of voluntary movements, occupies the anterior 

 Vards of the posterior limb in such a manner that the Facial and Hypoglossal 

 Fibres lie in the genu, next in order come the fibres to the upper Limb and 

 lastly those to the lower limb. In the posterior Vs^d of the posterior limb of the 

 internal capsule lies the great sensory path for "Common sensibility" and the 

 occipito-temporal cortico-pontic tract which passes from the occipital and temporal 

 lobes to the Pons. Furtliermore, fibres pass to and from the Cortex and Thalamus. 

 Close behind the posterior limb is the so-called "Carrefour sensitif" (Charcot's 

 Sensory Tract), through which the paths of the higher senses (Olfactory excepted) 

 pass. In the figure, only the fibres connected with the Optic Nerve are depicted 

 in their passage from this point to the Occipital Lobe. 



Disease of this "Carrefour" produces mixed Hemianaesthesia i. e. patients 

 feel, taste and hear less definitely or not at all on the opposite side, and do not 

 see with the Xasal half of the Eye on the same side and Temporal half of the 

 opposite eye, whereas disease of the posterior part of the posterior limb of the 

 Internal Capsule produces motor paralysis of the opposite side. 



The Anterior Limb contains chiefly fibres derived from the Frontal Lobe 

 and Caudate Nucleus; their course and function is unknown. The Caudate Nucleus 

 and its tail curl over the Internal Capsule to terminate by blending with the 

 Hippocampal Convolution and the Amygdaloid Nucleus; so that in this section 

 the Caudate Nucleus has twice been cut — at its body internal to the anterior horn 

 of the lateral Ventricle and at its tail near the descending horn. 



The lateral and 3rd ventricles communicate through the Foramina of 

 Monro. The pillars of the fornix are cut near their point of junction. The 

 posterior horn of the lateral ventricle is cut at the point where the inferior 

 horn begins. 



The white fibres of the Corona Radiata between the Cortex and the Corpus 

 Striatum is called the Centrum Semi-Ovale of ViCQ dAzyr. Ziehen. 



