Biology Reference
In-Depth Information
Figure 8.1 Events occurring at various levels as a response to nerve injury and repair.
(1) In the cell bodies in dorsal root ganglia and anterior horns of the spinal cord; (2) at the
site of injury; (3,4) at target level
—
motor endplates and cutaneous innervation; and
(5) at the cortical level (
Lundborg, 2005
).
proximal stump, they regenerate between the layers of basal lamina of
the Schwann cell processes reaching finally the target organs (
Geuna
et al., 2009
).
Second, changes occur to the target organ innervated by the damaged
nerve (
Geuna et al., 2009
). The regenerated axon must reinnervate the
proper target, and the target must retain the ability to accept reinnervation
and recover from denervation-related atrophy. Regeneration rate is approx-
imately 1/2 mm/day; therefore, more proximal injuries lead to longer
denervation periods and, despite optimal microsurgical techniques, the
functional results achieved after repair of severed peripheral nerves are much
less than optimal due to the target organ atrophy that takes place during the
period of denervation.
Third, changes occur to the proximal neural structures (e.g., dorsal root
ganglia and spinal cord) where the cell bodies of the neurons are located. As a
