220 



THE NERVOUS SYSTEM 



extended course alone, but are bound together in large num- 

 bers to make a nerve trunk. This trunk is composed of a 

 number of bundles of fibers, and is surrounded by a con- 

 nective tissue membrane known as the epineurium; the 

 separate bundles, or funiculi, are surrounded each by a similar 

 membrane called the perineurium; while inside the funiculi, 

 between the primitive fasciculi, is a delicate supporting tissue 



FIG. 64. Transverse section of a nerve. (Median.) 

 ep, epineurium; pe, perineurium; ed, ehdoneurium. (Landois.) 



known as the endoneurium , or the sheath of Henle. In con- 

 nection with this sheath there are nuclei belonging to the con- 

 nective tissue and to the nerve fibers themselves. The sheath be- 

 gins where the nerve fibers emerge from the white portion of the 

 centers, is interrupted by the ganglia in the course of the fibers, 

 branches as the bundle branches, and is lost before the terminal 

 distribution is reached. It is seldom found surrounding single 

 fibers. It is likewise rare for capillaries to penetrate it and reach 



