PNS Answers
A.
dorsal root (2): somatic sensory, visceral sensory
ventral root (2): somatic motor, visceral motor (preganglionic autonomic)
dorsal ramus (4): somatic sensory, somatic motor, postganglionic sympathetic, visceral
sensory
ventral ramus (5): somatic sensory, somatic motor, postganglionic sympathetic,
preganglionic sympathetic, visceral sensory
white ramus communicans (1): preganglionic sympathetic, [it also contains visceral
sensory fibers coming back from thoracic organs and the body wall, but that is more than
you need to know]
gray ramus communicans (1): postganglionic sympathetic [it also contains visceral
sensory fibers coming back from the body wall, but that is more than you need to know]
B. Spinal cord level C4 does not have sympathetic outflow. There are therefore no
preganglionic sympathetic fibers in the ventral root, and there is no white ramus
communicans. Note, however, that there is a gray ramus communicans that carries
postganglionic fibers from cervical sympathetic chain ganglion C4 (synapse) to spinal
nerve C4 to join its dorsal and ventral rami.
C. Spinal cord level S3 does not have sympathetic outflow. There are therefore no
preganglionic sympathetic fibers in the ventral root, and there is no white ramus
communicans. Note, however, that there is a gray ramus communicans that carries
postganglionic fibers from sympathetic chain ganglion S3 (synapse) to spinal nerve S3 to
joint its dorsal and ventral rami. Spinal cord level S3 does have parasympathetic outflow
and, therefore, preganglionic parasympathetic fibers in the ventral root. These fibers
enter the spinal nerve, its ventral ramus, and exit as pelvic (= sacral) splanchnic nerve for
the parasympathetic innervation of pelvic viscera.
D. Cell bodies of somatic sensory and visceral sensory nerves.
E. Cell bodies of postganglionic sympathetic nerves to the body wall and to thoracic
viscera.
F. In prevertebral (or pre-aortic) ganglia in the abdominal cavity.
G. In the anterior (or ventral) horn of the gray matter of the spinal cord.
H. In the (intermedio)lateral column of the gray matter of the spinal cord at levels T1 –
L2 and S2(3) – S4, and in the brainstem.
I. In the spinal (or dorsal root) ganglia.
J. Arrector pili muscles, smooth muscles in the walls of blood vessels, and sweat glands.
K. T1 - L2 and S2(3) - S4.