ioo8 



HUMAN ANATOMY. 



intervening nerve-fibres, a small amount of connective tissue prolonged from the 

 endoneurium of the nerve-bundles and accompanying the blood-vessels being also 



FIG. 852. 



Posterior root (sensory) 



Spinal cord 



Spinal ganglion 



FIG. 853. 

 Nerve-fibres, cut transversely 



Nerve-cell 



Anterior division 

 Section of spinal tierve, showiiiK its roots, ganglion, CO mmon trunk ami primary divisions. X 10. 



present. The chief ganglion -cells are from .o6o-.o8o nun. in diameter, but some 

 measure as much as .170 mm. and others as little as .025 mm. In sections 



(Fig. 853) they usually appear round or oval, 

 since only exceptionally are their processes to 

 be seen. Each cell is enclosed by a richly 

 nucleated fn/>sn/<- which is continuous with the 

 sheath of the nerve-tibiv>. M.st of the many 

 other oval nuclei that are conspicuous in sections 

 of the ^aiiijia belong to tin- neurilemma of the 

 fibres and. hence, are seen as chains ex 

 tending in different planes. Although many 

 of the nerve-cells within the spinal ganglia are 

 the cell bodies of the senary neurones, whose 

 processes course as medullated fibres within 

 the spinal nerves, many more are small cells, 

 \\lue axoiu-s never acquire, a medullary coat 

 and, dividing into peripheral and central 

 branches, run within the trunks and posterior 

 loots of the nerves as nonmedullated fibres. 

 i largely on the behavior of their axones, 

 D<HMel' has described eleven types of cells 

 within the ganglia. Hanson regards the "large" and "small" cells, whose axones 

 :ie meduliated and nonmedullated fibres respectively, as an important grouping, 



I Der I'.au ilt-r S|>nial^.m^li<-n, Ji-n.i, 1908. Dogiel describes eleven varieties of nerve-cells. 







mi. shf>\viiiK lid . 



surrounded In nu> Icau-d capsules, x 300. 



