472 



THE BRAIN 



posterior divisions of the lentiform portion of the capsule. 

 Through the anterior division, which lies between the lentiform 

 and caudate nuclei, pass the fibres of the anterior peduncle 

 of the thalamus, and fronto-pontine fibres which associate the 

 cells of the frontal part of the cortex of the hemisphere with 

 the nerve cells of the ventral part of the pons. The genu 

 consists of fibres which convey motor impulses from the 

 motor area of the cortex of the hemisphere to the nuclei of 

 the nerves which supply the muscles of the face and tongue 

 of the opposite side. The posterior division of the lentiform 



Fibres of medullary laminae oroi 

 Upper limit of int. capsule 

 Area in relation | 



to putamen 

 Frontal fibres of 

 corona radiata 



Area in relation to globus pallidus 



Basis peclunculi 



jk Lateral 

 Afe geniculate body 

 ,-'^V Optic radiations 



Medial geni- 

 culate body 



Olfactory bulb 

 Anterior commissure . 



Optic tract .ft 



Corpus mamillare / / , 



Oculo-motor nerve / / 



Pyramidal fibres / 



Cut surface of pons / 



Pyramid 



Olive 



VVl 



Trochlear nerv< 



Lateral lemniscus 

 dial lemniscus 

 Brr.chium pontis 



flr 



FIG. 190. Dissection of Internal Capsule and Pyramidal Fibres. 



portion of the capsule, which lies between the lentiform 

 nucleus and the thalamus, is separable into (i) an anterior 

 two -thirds, which consists principally of fibres conveying 

 motor impulses to the nuclei of the nerves which supply 

 the muscles of the upper limb, trunk, and lower limb of 

 the opposite side, in that order from before backwards, 

 together with some sensory fibres ; and (2) a posterior third, 

 which contains sensory fibres, that is, fibres conveying ordinary 

 sensory impulses to the cortex of the hemisphere. The 

 majority, if not all, of the sensory fibres spring from the 

 thalamus, and they pass to the parietal, occipital, and temporal 

 lobes. The fibres which spring from the posterior part 

 of the thalamus and pass through the posterior or retro- 



