ANATOMY AND SUBDIVISION OF NERVOUS SYSTEM 117 



A 



a 



I fblliunt .Thalama 



r-^r-^K^J \ I 



Mamtfhalai 



Centillium 



Myelencepholal 



Fig. 47. Reconstruction of the brain of a 6.9 mm. human embryo 

 (about four weeks old): A, Lateral view; B, in median sagittal section; 

 Ceph.flex., cephalic flexure. (After His, from Prentiss' Embryology.) 



Hypophysis (anterior lobe) - - 



Ventro-lateral plate 

 Dorso-lateral plate--- 



] 



Fig. 48. Diagram of the inner surface of the human brain, based on a 

 specimen of about the same age as shown in Fig. 47. The shaded area is 

 the ventro-lateral plate of the neural tube, giving rise to the motor centers. 

 Its upper boundary is marked by a groove on the ventricular surface, the 

 sulcus limitans, which separates the ventro-lateral plate from a dorso- 

 lateral plate (unshaded), which gives rise to the sensory centers and chief 

 correlation centers. (After His, from Morris' Anatomy.) 



