SPINAL NERVES. 



441 



n 



the 



per- 



Fi S- 284 - 



lieved to extend 

 pheral direction. 



8. The ganglion-fibres thus 

 arising, which frequently arch 

 round, or embrace the cells 

 with several circular turns, are 

 at first fine, or 5 oV o to -g^v of 

 an inch ; but increase up to 

 Woo, s oVo, and even to 3TF Vtf 

 of an inch, while still with- 

 in the ganglion, thus becom- 

 ing thick fibres. The special 

 sheaths of the pale processes 

 are, however, continued over 

 the fibre only till it leaves the 

 ganglion, when the common 

 perineurium takes their place. 



It is clear that the subdivisions of the trunks of the spinal nerves 

 formed as already explained, will contain motor, sensory, and gan- 



Fig. 285. 



From the Gasserian ganglion of an adult, a, a. 

 Ganglion cells with their nucleus, nucleated cap- 

 sule, and pigment. t. Tubular fibres running 

 among the cells in contact with their capsule, g. 

 Gelatinous (Remak's) fibres also in contact with 

 the ganglion-cells. (Magnified 320 diameters.) 



Connection between nerve-fibres and nerve-cells ; from the roots of a spinal nerve of the ray. A. 

 A nerve-cell escaped by pressure from the capsule formed around it, by the dilated sheath of the 

 nerve-tubule ; it shows also the gradual disappearance of the outer portion of the substance of the 

 nerves as it comes into relation with the cells. B. A nerve-cell inclosed within a dilated portion of 

 the neurilemma of a nerve; part of the granular material of the cell is continuous with the axis- 

 fibre of the nerve in the course of which it is inserted. 



glionic nerve-fibres. The coarse fibres are finally sent to the mus- 

 cles, and the finer are given off in the cutaneous nerves, and those 

 of other sensitive parts. The ultimate distribution of the ganglionic 

 fibres has not been anatomically settled. They are, however, pro- 

 bably mostly given off in the vascular nerves of the extremities, 

 glands, and skin. 



The proportion of the coarse to the fine fibres in the main trunks 

 of the spinal nerves, is as 10 to 11; while in the muscular nerves it 



