106 Anatomy of the Nervous System 



caudatiis and nucleus lentijormis sen lenticularis) is not really 

 the fundamental one in the corpus striatum, however, the 

 lentiform nucleus consisting of two parts, the lateral putamen 

 and the medial globus pallidus, of which the putamen is much 

 more closely related to the caudate nucleus than to the 

 globus pallidus. The putamen and caudate nucleus together 

 form the neostriatum, the globus pallidus is the palaeo striatum, 

 being much older both phylogenetically and ontogenetically, 

 and the amygdala is called the archi striatum according to this 

 terminology. 



The caudate nucleus, in animals where it is distinct, has 

 a large anterior portion or head {caput) and a greatly elongated 

 tail {cauda) which runs back from the caput dorso-medial to 

 the internal capsule and curves ventrally in the posterior part 

 of the hemisphere. Finally, it turns anteriorly again and 

 ends ventral to the globus pallidus in close topographical 

 relation with the amygdala. In the rat, the bundles of the 

 internal capsule come together posteriorly into a compact 

 mass separating the corpus striatum from the thalamus, but 

 even here there is no definite separation of a caudate nucleus. 

 Ordinary cell stains likewise show no distinction, so the 

 caudate nucleus may be considered to be represented by a 

 considerable anterior portion and a decreasing dorsal, 

 posterior, and postero-ventro-medial portion of the common 

 mass (neostriatum) formed by it and the putamen. At the 

 anterior end of this mass, a large and distinct nucleus projects 

 from it antero-medially under the lateral ventricle into the 

 region of the septum. This nucleus accumhens septi (collictdus 

 striatiy is found in nearly all mammals, as well as in lower 

 vertebrates, but has not yet been recognized in man. The 

 caudate nucleus is made up of two parts which are distinct 

 in the embryo but are indistinguishable in the adult. The 

 medio-ventral portion of the head of the caudate belongs to 

 the olfactory system along with the nucleus accumbens, as 



^Nucleus parolfactorius lateralis of Johnston. 



