200 TOPOGRAPHICAL ANATOMY OF THE 



Dissection. — By a median incision separate the halves of what 

 remains of the cerebrum. r)f one lialf make a series of horizontal 

 sections about four or five millimetres thick. The other half should be 

 cut into similar slices by vertical transverse incisions. In making these 

 sections it is well to use a long, broad-bladed knife or a razor. 



The corpus striatum, etc. — The so-called basal ganglia of the 

 cerebral hemisphere consist of masses of grey matter separated by 

 intervening strata of white matter. The ganglia are the caudate and 

 lentiform nuclei of the corpus striatum, the claustrum and the amyg- 

 daloid nucleus. 



A partial examination of the caudate ^ nucleus (nucleus caudatus) 

 was made after the lateral ventricle had been opened (page 189). The 

 nucleus consists of a mass of grey matter of curved, pear-shaped form, 

 with a head (caput nuclei caudati) that is thick and forms a projection 

 in the anterior part of the ventricle. From the head the nucleus 

 tapers somewhat rapidly to a tail (cauda nuclei caudati) that follows 

 the inferior cornu of the ventricle to end in the amygdaloid - nucleus 

 (nucleus amygdalse) in the roof of the extremity of the cornu. From 

 what has been seen, and from the sections now under examination, it 

 is manifest that the caudate nucleus may be described as having two 

 surfaces. A free ventricular surface is covered by the ependyma of the 

 ventricle. A deeper face is embedded in the substance of the cerebral 

 hemisphere, and is mainly in contact with the internal capsule. 



The lentiform nucleus^ (nucleus lentiformis) is an irregularly lens- 

 shaped mass of grey matter placed lateral and ventral to the caudate 

 nucleus and the thalamus. Smaller than the caudate nucleus, it is 

 connected with it by strands of grey matter that cross the intervening 

 white stratum. In addition, the two nuclei are continuous with each 

 other and with the grey matter of the surface of the hemisphere at the 

 olfactory tubercle. 



The claustrwrii^ is a thin layer of grey matter lateral to the corpus 

 striatum and very nearly co-extensive with the insula, that is, with the 

 convolutions hidden in the Sylvian fissure. 



The term internal capsule (capsula interna) is applied to the white 

 matter separating the caudate nucleus and the thalamus on the one side 

 from the lentiform nucleus on the other. The continuity of the 

 capsule is much interfered with anteriorly by the grey strands that 

 cross from one nucleus to the other. In horizontal sections, the 

 capsule is bent opposite the stria terminalis at what is known as 



1 Cauda [L.], a tail. 



2 dfivy8d\oeidT)s (amygdalceides) [Gr.], like the almond. 



2 Lens [L.], a lentil, lens. Forma [L.], form. Nucleus [L.], a kernel, a nut. 

 * Claustra [L.], a barrier, a barricade, a bulwark. 



