THE BRAIN 



it thickens considerably, and at the base of the brain it 

 comes to the surface, at the substantia perforata anterior, 

 and becomes continuous with the grey matter of the cerebral 

 cortex. Its extent corresponds very nearly with the area 

 occupied by the insula, and its lateral surface shows ridges 

 and depressions corresponding to the insular gyri and sulci. 



Capsula Interna. This term is applied to the broad band 

 of white matter which intervenes between the lentiform 

 nucleus laterally, and the thalamus, stria terminalis, and 

 caudate nucleus on the medial side. Anteriorly it is much 



Fibres of medullary laminae CorQna radiata 

 Upper limit of int. capsule 

 Area in relation | 



to putamen 

 Frontal fibres of 

 corona radiata 



Area in relation to globus pallidus 



f* Basis pedunculi 



/jjt Lateral 

 j\ gtniculate body 



t~ Optic radiations 



.A Medial geni- 

 V . culate body 



Olfactory bulb / / > 



Anterior commissure / / 

 Optic tract S / 

 Corpus mamillare / 

 Oculo-motor nerve -- / 

 Pyramidal fibres / 

 Cut surface of pons 



Pyramid 

 Oliv 



Trochlear nerve 



Lateral lemniscus 

 Medial lemniscus 

 Brachium pontis 



FIG. 218. Dissection of Internal Capsule and Pyramidal Fibres. 



broken up, by the connecting bands of grey matter which 

 pass between the head of the caudate nucleus and the 

 anterior part of the putamen of the lentiform nucleus (Fig. 

 215), but more posteriorly it forms a solid white mass of 

 nerve fibres. When seen in horizontal section, the internal 

 capsule is bent upon itself opposite the interval between the 

 caudate nucleus and the thalamus (Fig. 216). This bend, 

 which points medially, is called the genu. About one-third 

 of the internal capsule lies anterior to the genu, and this 

 part is called the anterior limb ; the remaining two-thirds, 

 which lie posterior to the genu, constitute the posterior limb. 



Connections of the Internal Capsule. The internal capsule 

 is directly continuous below with the basis of the cerebral 



