CHAPTER XXXIV 
THE NERVOUS SYSTEM OF MAN 
359. Parts of the Nervous System. — The nervous system 
of man consists of the same general parts as the nervous 
system of the frog (see page 88). There is a brain and 
spinal cord, from which nerves extend to the special senses, 
the muscles, the heart, and the stomach. When the brain 
of man is compared with that of the frog, it is obvious 
that the cerebrum of man is proportionately larger. Al¬ 
though some of the other parts of the brain appear unlike 
the corresponding regions in the frog, scientists tell us that 
they are really the same. 
380. The Nerve Cell. — The nervous system of man con¬ 
sists of many thousands of nerve cells which differ from all 
other cells in having more parts and branches (Figures 
413, 414, 415). Examination shows that the nerve cells 
have a prominent nucleus surrounded by cytoplasm, which 
grows out into a number of branches called fibers. The 
shorter branches divide and form, together with the branches 
from the neighboring nerve cells, a mass of tangled fibers. 
There is usually one unbranched fiber, perhaps several feet 
long, which ends either in the skin, in some muscle, or in 
the spinal cord or brain. When this long fiber reaches the 
muscle or skin, it divides into several fine branches. All 
these branches which arise from a nerve cell belong to it, and 
in this connection the word cell includes all the branches, 
the nucleus, and the cytoplasm. 
361. The Location of the Nerves. — The nerve fibers 
which have the same work to do occupy certain definite 
466 
