858 



THE NERVOUS SYSTEM 



nuclei. (2) Fibres which pass in both directions between the thalamus and the corpus striatum 

 (caudate nucleus especially). Those are more abundant anteriorly, and necessarily pass 

 through the internal capsule. (3) The ansa lenticularis, a usually distinct bundle, composed 

 largely of fibres passing between the thalamus and lenticular nucleus. It passes from the under 

 aspect of the anterior tubercle of the thalamus and curves below through tin; internal capsule 

 to the under surface of the lenticular nucleus, and there its fibres are distributed upwards I trough 

 its medullary lamina to the globus pallidus and put amen. Some enter the internal capsule 

 and reach the cortex, chiefly that of the temporal lobe. (4) Fibres connecting both nuclei (chiefly 

 the caudate) with the substantia nigra of the inesencephalon. These pass through the hypo- 

 thalamic region and along the cerebral peduncle. 



The claustrum is a triangular plate of grey substance which is embedded in the 

 white substance between the lenticular nucleus and the insula. Its inner surface is 

 concave, conforming to the convexity of the putamen. The sheet of white substance 

 intervening between it and the putamen is known as the external capsule. Its 

 outer surface shows ridges or projections in section which conform to the neighbour- 

 ing gyri of the insula, and it is spread through an area which quite closely corresponds 

 to that of the insula. Below and anteriorly it becomes continuous with the cortex 



Fio. 639. CORONAL SECTION OF TELENCEPHALON THROUGH THE ANTERIOR COMMISSURE, OPTIC 

 CHIASMA, AND TRUNK OF CORPUS CALLOSUM. (After Toldt, " Atlas of Human Anatomy," 

 Rebman, London and New York.) 



CAVDATB HECLBDS 

 (UEAU) 



IHTKRNAL CAPSI'I.B 

 (FROtfTAL I'OK- 

 TIOX) 



. 



:f /, 



aiofirs 



PALLl- 



DUS 



LENTI- 

 CULAR 

 XUCLE- 

 VS 



CAPSL'LE 

 CLAUSTRUM 



VENA TERMIXAI.1S 



IXTER VEXTRiri: 

 I.AK fDRAHEX 

 (MOSROI) 



AXTF.nmn PERFOR- 

 ATED SUBSTANCE 



LOKOITVD1HAI 



riasURB 



OOMfVS 



CALLOSUM 



AXTKRIOR 



ro/.'.vr or 



^ I.ATKIIM. 



rSKIRKLB 



I'/ioitrolfi 

 ri.vxrs of-- 



I. A TKItAL 

 YKXTKH-LK 



8BPTUM 



" I'f.'Ll.ri'fi-r.u 



ni.r.vxt< OF 



FORSIX 



LATERAL 



i i**niE 



-T;. r// , 



riTRr OF 



IXSTLA 



, OPTIC TRACT 



OPTIC 

 CHIASMA 



I\FERIOR COM-VISSTKE 



of the anterior perforated substance and with the lenticular nucleus at the region of 

 its junction with the latter. Above and posteriorly it gradually becomes thinner, 

 and finally disappears in the white substance about it. In origin it is thought to be 

 a detached portion of the cortical grey substance of the insula. 



The amygdaloid nucleus (nucleus amygdala*) is represented by the amygdaloid 

 tubercle, which has already been described in the extremity of the inferior cornu of 

 the lateral ventricle (figs. 61 4 and 637) . It is an almond-shaped mass of cells joined to 

 the tail of the caudate nucleus, continuous above with the putamen and anteriorly 

 with the cortex of the temporal lobe. 



Apparently the chief connection of the amygdaloid nucleus is with the anterior perforated 

 substance, and this by way of the stria terminalis oj the thalamus. The longitudinal fibres 

 coursing in this bundle for the most part arise in the nucleus. Thence they pass backwards in 

 the roof of the inferior cornu, then curve upwards and anteriorly just outside the pulvinar of 

 the thalamus, and run in the floor of the body of the lateral ventricle along the line of the 

 genu of the internal capsule, forming the boundary between the lhalamus and the caudate 

 nucleus (figs. 614 and 638). Upon reaching the anterior commissure, the fibres turn ventrally and 

 disperse, and are said to terminate in the anterior perforated substance. The amygdaloid 



