408 



BIOLOGICAL PHYSICS 



motor areas, and therefore issue as proper cerebro-spinal 

 neurons, with their nerve terminal expansions situated at 

 various levels, from the cephalic base to the posterior 

 extremity of the spinal cord. 



The peculiar local distribution and textural arrangement 

 and relationships of the grey and white substances of the 



FIG. 131. DIFFERENT VIEWS OF A PORTION OF THE SPINAL CORD FROM 



THE CERVICAL REGION WITH THE ROOTS OF THE NERVES. Slightly 



enlarged. (Allen Thomson.) 



In A, the anterior surface of the specimen is shown, the anterior nerve-root of the 

 right side having been divided ; in B, a view of the right side is given ; in C, the 

 upper surface is shown ; in D, the nerve roots and ganglion are shown from below, 

 i, the anterior median fissure ; 2, posterior median fissure ; 3, antero-lateral im- 

 pression, over which the bundles of the anterior nerve-root are seen to spread 

 (this impression is too distinct in the figure) ; 4, postero-lateral groove into which 

 the bundles of the posterior root are seen to sink ; 5, anterior root ; 5', in A, the 

 anterior root divided and turned upwards ; 6, the posterior root, the fibres of which 

 pass into the ganglion, 6' ; 7, the united or compound nerve ; 7', the posterior 

 primary branch, seen in A and D to be derived in part from the anterior and in 

 part from the posterior root. 



brain and cord respectively undergo great changes both 

 within and without the skull, these relationships, in regard 

 to peripheral and central, or superficial and deep layering, 

 undergoing a complete textural metastasis on the elimi- 

 nation of the purely mental structural elements, whereby, 

 after passing through the medulla oblongata, the grey 

 matter assumes a united bicrescentic (Fig. 131), or H 

 shape, surrounded by the white matter, in well-defined 



