504 



THE NEKVOUS SYSTEM 



On either side of the third ventricle, dorso-lateral from the red 

 nucleus, is the large ovoid group of nuclei which collectively form 

 the optic tlialamus. The group of thalamic nuclei include the 



FIG. 391. A SECTION OF THE HUMAN BRAIN STEM, AT THE MID-LEVEL OF THE RED 



NUCLEUS. 



Cm, mammillary body; Cop. posterior commissure; Csth, subthalamic body of Luys; 

 FeQa, efferent fibres from the roof of the mesencephalon ; fp, perforating fibres of the 

 crusta ; frtf, Meynert's bundle ; Gem, ectomarnmillary ganglion ; Gb, ganglion habenulse ; 

 Glp, pineal gland ; glp, globus pallidus ; ///, oculomotor nerve ; ImL lateral medullary 

 layer of the thalamus; Narc, arcuate nucleus of the thalamus; Nc, caudate nucleus; 

 Ncop, nucleus of the posterior commissure; Nl, centre median of Luys; Nlve, external 

 latero- ventral nucleus of the thalamus; Ntg, red nucleus; Ntgd, dorsal portion of same; 

 Pcm, peduncle of the mammillary body; Pp, crusta; Pu, putamen; Pul. pulvinar; Stri, 

 intermediate layer ; Til, optic tract ; Tpt, transverse tract of the peduncle ; Tri, inter- 

 crural trigone ; VIII, third ventricle ; VS, bundle of Vicq d'Azyr. Weigert's stain, 

 x If. (After Marburg.) 



" centre median" or nucleus of Luys, a small oval cell group lying 

 just dorso-lateral from the red nucleus, and separated from it 

 by a narrow interval of white matter; the lateral cell mass or 

 lateral nucleus ; a ventral group of cells ; a small anterior nucleus ; 

 a dorsal cell group ; a large rounded posterior extremity, the pul- 

 vinar ; together with several nuclei of minor importance.* The 



* The limited space at our disposal, and the indeterminate state of our pres- 

 ent knowledge of the relations of these several cell groups to the fibre paths of 

 the brain, does not warrant a detailed description of the subdivisions of the 

 optic thalamus. For its minute structure, so far as it is at present known, the 

 reader is referred to the excellent text-books of Barker and Obersteiner, and to 

 the works of Nissl, von Monakow, and Marburg. 



