74 PSYCHOBIOLOGY 



'spinal ganglion'. Some of these fibers (somatic fibers) run in the 

 nerve and its branches directly to endings in striped muscles. Others 

 (visceral or splanchnic fibers) leave the nerve beyond the spinal ganglion 

 and run over the white rami communicantes to the ganglia of the 

 sympathetic chain (the lateral ganglia). Certain of the splanchnic fibers 

 arborize each around a number of cells in the sympathetic ganglia; others 

 run through these ganglia to the collateral ganglia, arborizing in the 

 same way there. The axons from lateral and collateral ganglia run to 

 the smooth muscle tissue or to glands. Thus, the current leaving the 

 spinal cord over a single splanchnic fiber is distributed finally to a 



FlG. 62. End-plates (motor nerve endings) in striped muscle of a rat. Magnified 

 170 diameters. (Szymonowicz, Histologic.) 



number of axons. Many of the axons from the lateral ganglia return 

 to the spinal nerve over the gray rami [Figs. 76, 77 and 78]. 



What has been said about spinal afferent neurons applies in general 

 to the efferent neurons of the cranial nerves, whose cells lie in the nuclei 

 of the medulla, pons and mid-brain. 



As the fiber approaches its termination in voluntary (striated) muscle, 

 it branches repeatedly, each fiber thus coming into relation to a number 

 of muscle fibers. When a branch reaches a muscle fiber, the medullary 

 sheath ceases abruptly, the neurilemma becomes continuous with the 

 sareolemma beneath which the fiber branch terminates in the end plate, 



