430 



PHYSIOLOGY 



(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. 



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

 cells, known as the outer line of Baillarger. 



(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. 



m 



Tangential layer. 



Outer line of Bail- 

 larger. 



c. Inner line of Bail- 

 larger. 



'L 



FIG. 221. Motor leg area. 



(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. 222). 



A careful study of the distology of the different parts of the cortex in 

 man enables us to distinguish certain types of structure characteristic of 

 various regions of the grey matter. In attempting by such means an 

 histological localisation of functions we have to take into account : 

 (a) The thickness of the cortex. 



