‘THE SYMPATHETIC NERVOUS SYSTEM. 663 
the cells of a sympathetic ganglion. There are three known courses for such a 
fibre to take in relation to the sympathetic system—(a) J¢ may end in the ganglion 
with which it is immediately related; (>) ct may course upwards or downwards in 
the commissural cord to reach a neighbouring ganglion ; (¢) af may pass beyond 
the gangliated cord to end in relation to cells of the peripheral (collateral) gangha 
along with fibres of distribution from the sympathetic gangha. These fibres are 
splanchnic efferent fibres; motor for the unstriped muscular tissue of the vessels 
and viscera, and 
secretory for the 
glands in the splanch- 
nic area. The fibres 
from the dorsal root \ 
of the spinal nerve / 
entering into the 
composition of the 
white ramus com- 
municans are the 
axons of spinal gang- 
lion cells. They con- 
stitute the splanchnic 
afferent fibres, and = 
probably traverse the 
sympathetic  gang- 
hated cord, passing 
upwards, downwards, 
and outwards, with- 
out being connected \\ SPLANCHNIC 
. a = AFFERENT 
with its cells. They 
are the sensory fibres 
for the viscera, which 
they reach along with 
the peripheral / 
branches arising from 
the sympathetic cord 
itself. It is not cer- 
tain that fibres from 
COMMISSURAL 
FIBRE 
CENTRAL 
GANGLION CELLS 
AND AXONS 
SPLANCHNIC 
EFFERENT 
PERIPHERAL 
FIBRE 
p 
the dorsal ganglia are Z soLeTeRA TY SS 
only found in con- \ s vie Z 
nexion with nerves ey. be 
provided with distinct 17 
white rami. Similar a ft 
medullated fibres are jew 
found also in the 
gray rami communi- 
eantes. i 
The non - medul- 
lated fibres in the Fic. 476.—-SCHEME OF THE CONSTITUTION AND CONNEXIONS OF THE 
sympathetic system GANGLIATED CORD OF THE SYMPATHETIC. 
are derived from the The gangliated cord is indicated on the right, with the arrangement of the fibres 
P ‘ arising from the ganglion cells. On the left the roots and trunks of 
Bs of the a ia sa spinal. nerves are shown, with the arrangement of the white ramus 
thetic ganglion cells. communicans above and of the gray ramus below. 
They have different ] 
destinations. (a) Some fibres appear to contribute to the formation of the comm issurall 
cord connecting the ganglia together, and to end in aborisations round the cells of a 
neighbouring ganglion. (b) Non-medullated fibres form a large part of the system 
of peripheral (splanchnic efferent) branches, streaming into the splanchnic area in an 
irregular manner, both from the ganglia and the connecting commissures. (c) The 
gray rami communicantes form a series of non-medullated fibres (with a small 
number of medullated fibres intermingled) proceeding centrally from the ganglia to 
