486 



PHYSIOLOGY 



the grey matter. In addition bands of tangential fibres are seen 

 running parallel to the surface in certain situations, viz. : 



(a) A layer of very fine fibres just under the surface of the cortex. 

 This layer is especially marked in the hippocampal convolution and 

 is but slightly developed in other regions of the cortex. 



(1) Molecular or outer 

 fibre lamina. 

 0.34 mm. 



(2) Pyramidal or outer 

 cell lamina. 

 0.90 mm. 



(3) Granular layer or 

 middle cell lamina. 

 0.22 mm. 



(4) Inner fibre lamina. 

 0.22 mm. 



(5) Polymorphic or inner 

 cell lamina. 

 0.31 mm. 



a. Tangential layer. 



6. Outer line of Bail- 

 larger. 



c. Inner line of Bail- 

 larger. 



FIG. 220. Motor leg area. 



(6) A layer between the molecular layer and the layer of pyramidal 

 cells, known as the outer line of Baillarger. 



(c) Internal to the granule layer is another zone of fibres, the 

 inner line of Baillarger, giving its name to the inner fibre lamina. 



(d) In the part of the occipital cortex, distinguished as the visuo- 

 sensory area, which receives fibres of the optic radiations, a special 

 layer of tangential fibres is observed running through the middle of the 

 granular layer and dividing it into two parts. This is known as the 

 line of Gennari (Fig. 221 A). 



