Alar plate (yellow)
- Cell bodies in the alar plate form nuclei which constitute the
dorsal gray horn
(or columns) of afferent neurons that extend the length of the cord. Dendrites
of neurons in the alar plate receive and relay incoming general somatic and
general visceral sensory (GSA & GVA) information from axons of the
pseudounipolar neurons located in the
dorsal root ganglion
and carried to the cord in
dorsal roots
of spinal nerves.
Basal plate (red) - Cell bodies here form the uninterrupted
ventral gray horn
(or columns) of efferent neurons that extend the length of the cord. Axons of
these neurons project general somatic efferent motor fibers to skeletal muscle
and form the
ventral roots
of the spinal nerves.
Intermediate gray horn
of the basal plate is present in a more limited portion of the cord. In the
thoracic segments, lumbar segments L1 - L3, and sacral segments S2 - S4 of the
cord a
lateral or (intermediate) gray horn
is present at the junction of alar and basal plates. Cells here provide the
first of 2 neurons general visceral efferent fibers that supply smooth muscle
and glands. Axons of these cells exit the cord via the
ventral roots.
