106 Neuroanatomy: Draw It to Know It
Know-It Points
Spinal Cord Overview
■ Th e posterior, middle, and anterior white matter form
the posterior, lateral, and anterior funiculi, respectively.
■ Th e gray matter of the spinal cord divides into the
posterior horn, intermediate zone, and anterior horn.
■ Th e gray matter of the spinal cord comprises Rexed
laminae, which are numbered I to X.
■ Laminae I–VI are the sensory laminae.
■ Lamina VII is the spinocerebellar and autonomic
lamina.
■ Laminae VIII and IX are the motor laminae.
■ Lamina X surrounds the central canal.
■ In the lumbosacral cord, white matter is small and
gray matter is large.
■ In the thoracic cord, white matter is moderately large
and gray matter is small.
■ In the cervical spinal cord, both the gray and white
matter regions are large.Ascending Pathways
■ Th e posterior column pathway comprises large sensory
fi bers, which carry vibration, two-point discrimination,
and joint position sensory information.
■ Th e gracile fasciculus carries large fi ber sensory
information from the lower body.
■ Th e cuneate fasciculus carries large fi ber sensory
information from the upper body.
■ Th e anterolateral system comprises small fi ber
sensory pathways, which carry pain, itch, and thermal
sensory information.
■ Th e anterolateral system includes the spinothalamic
tract and the spinal-hypothalamic and spinal-
brainstem pathways.
■ Th e spinocerebellar tracts comprise large sensory
fi bers, which carry joint proprioception to the
cerebellum for the coordination of movement.Descending Pathways (Advanced)
■ Th e anterior corticospinal tract innervates proximal
musculature for gross motor movements.
■ Th e lateral corticospinal tract innervates distal
musculature for fi ne motor movements.
■ Th e hypothalamospinal tract carries hypothalamic
control of autonomic function.
■ Th e rubrospinal tract innervates the upper cervical
spinal cord to produce arm fl exion.
■ Th e tectospinal tract innervates the upper
cervical spinal segments to produce contralateral
head turn.
■ Th e reticulospinal tracts and vestibulospinal tracts
maintain posture through the activation of
antigravity muscles.