352 



THE PERIPHERAL NERVOUS SYSTEM 



greater part of, the dorsal funiculi. Peripheral processes of the ganglion cells 

 join the ventral root fibers in the trunk of the nerve (Fig. 342). At 10 mm. (Fig. 

 341) the dorsal root fibers have elongated and the cellular bridges of the ganglion 

 crest between the spinal ganglion have begun to disappear. In transverse sec- 

 tions at this stage (Figs. 307 and 342) the different parts of a spinal nerve may be 

 seen. The trunk of the nerve just ventral to the union of the dorsal and ventral 



Ophthal. dio. 

 Sup.max.div.- 

 N.ma st/c a toriu S. 

 Inf.max.div: 



ix-x-y/ gang, crest. 



D.I 



FIG. 340. Reconstruction of a 6.9 mm. embryo showing the development of the dorsal root fibers from 

 the spinal and cerebral ganglia (Streeter). X 16.7. 



roots gives off laterally the dorsal, or posterior ramus, the fibers of which supply 

 the dorsal muscles. The ventral ramus continuing gives off mesially the ramus 

 communicans to the sympathetic ganglion and divides into the lateral and ventral 

 (anterior) terminal rami. The efferent fibers of these rami supply the muscles 

 of the lateral and ventral body wall and the afferent fibers end in the integument 

 of the same regions. 



