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TEXT-BOOK OF PHYSIOLOGY 



AMYGDAIA 



lection of gray and white matter and receives its name from the fact that it 



presents on cross-section a striated appearance. The larger portion of this 



body is embedded in the cerebral white matter, while the smaller portion 



projects into the anterior part of the lateral ventricle. A dissection of this 



nucleus shows that it is subdivided by a band of white matter into two 



smaller nuclei, viz. : the caudate and the lenticular nuclei. 



i. The caudate nucleus is a pyriform body which corresponds with the 



intra-ventricular portion of the corpus striatum. It consists of a head, 



an arching body and a tail. The head, which is thick and large, projects 



into the anterior cornu of the ventri- 

 cle; the body arches across the ven- 

 tricle from before backward and 



/M^^^ **"*%. from within outward, while the tail 



is directed downward and forward 

 to become associated with the collec- 



m t - 1 -'" m tion of gray matter situated beneath 



the lenticular nucleus and known as 

 ^/ the amygdaline nucleus. Anteriorly, 



^^^ the caudate nucleus is united with 



the lenticular nucleus by a narrow 

 bridge of gray matter, partially sub- 

 divided by small bands or strands of 

 nerve-fibers passing through it. 

 2. The lenticular nucleus is an irregularly 

 triangular pyramidal- shaped body 

 and corresponds with the extra-ven- 

 tricular portion of the corpus stria- 

 tum, the portion embedded in the 

 cerebral white matter. The apical 

 extremity of the nucleus is directed 

 toward the median line while its 

 _^ convex base is directed toward and 



runs almost parallel with the gray 

 FIG 2 4 o.-Two VIEWS OF A MODEL matter of the Island of ReiL The 



OF THE STRIATUM. A, Lateral aspect ; B, , , , ,. r 



mesial aspect. (Spitzka) general appearance and relation of 



these nuclei, are shown in Figs. 240 



and 241. A horizontal section of the lenticular nucleus shows that it is 

 divided by two lamina of white matter into three portions. The two in- 

 ner, from their pale yellow color, form the globus pallidus, the outer, 

 somewhat darker in color, is termed the putamen. External to the len- 

 ticular nucleus is a thin stratum of gray matter, arranged more or less 

 vertically, and placed between the outer surface of the lenticular nucleus 

 and the cortex of the Island of Reil, and known as the claustrum. 

 The optic thalamus is an oblong mass of gray matter situated between 

 the sensor, afferent pathway and the cortex of the cerebrum. The anterior 

 and posterior extremities of each thalamus present enlargements known 

 respectively as the anterior tubercle and the posterior tubercle or pulmnar. 

 The mesial surface of the thalamus forms the lateral wall of the third ventri- 

 cle and is covered by epithelium resting on a thin layer of ependyma. 



A transection of the thalamus shows that it is not only covered externally 



--AMYGDALA 



