NERVE-CELLS. 



215 



The portions of the gray matter which approach the surface 

 of the cord anteriorly and posteriorly are called the anterior 

 (or ventral) and posterior (or dorsal) horns or cornua ; the 

 anterior horns are broader and shorter ; the posterior longer 

 and narrower. 



From these horns at intervals proceed the posterior (sensory) 

 and anterior (motor) roots of the spinal nerves. 



Cross-section of the spinal cord of a newborn child, showing the distribution within 

 the gray matter of the collaterals from the neurites of the white matter (R. y 

 Cajal ). a, anterior fissure ; B, pericellular branches of the collaterals from the 

 anterior column ; C, collaterals of the anterior commissure ; D, posterior bundle 

 of collaterals in the posterior commissure ; E, middle bundle of the posterior 

 commissure ; /, anterior bundle ; G, collaterals from the posterior column ; H, 

 senso-motory collaterals from the posterior column ; I, pericellular terminations 

 of collateral's in the posterior horn ; J, collateral terminations in the column of 

 Clarke. 



The nerve-cells of the cord (Fig. 76) are arranged in definite 

 longitudinal series or columns, as follows : (a) in the anterior 

 horn are numerous very large stellate multipolar motor cells ; 



