NERVE INJURY
NERVOUS SYSTEM
nerve injury
Damage or severance of
conducting fibres within a
nerve
as a
result of trauma, causing loss of skin
sensation and muscle power. (See
neuro-
pathy
for nerve damage from causes
other than injury.)
If a peripheral nerve (a nerve outside
the brain or spinal cord) is only partially
severed, the cut fibres may be able to
regenerate. Provided the severed ends
are still aligned, new fibres can grow
across the cut to rejoin the connection,
restoring function. If a nerve is totally
severed, the individual fibres cannot
regenerate successfully and there is no
recovery of function. Nerve tracts within
the brain and spinal cord are structural-
ly different from the peripheral nerves,
and severed fibres in these tracts do not
regenerate. For example, vision cannot
be restored if the
optic nerves
are cut.
Microsurgery
can sometimes be used
to stitch a severed peripheral nerve into
place, but recovery is rarely complete.
nerve, trapped
Compression or stretch-
ing of a nerve, causing numbness,
tingling, weakness, and, sometimes, pain.
Common examples of a trapped nerve
include
carpal tunnel syndrome
,
in which
pressure on the median nerve as it
passes through the wrist causes symp-
toms in the thumb, index, and middle
fingers; a
disc prolapse
,
in which pressure
on the nerve root leading from the spinal
cord produces symptoms in the back
and legs; and
crutch palsy
, in which the
radial nerve presses against the humerus
(upper-arm bone), producing symptoms
in the wrist and hand.
A damaged nerve may take some time
to heal. In severe cases, surgical decom-
pression to relieve pressure on the nerve
may be necessary.
nervous breakdown
A nontechnical
term used to describe unusual behav-
iour (such as episodes of tearfulness or
shouting and screaming) that may be
part of a crisis of severe
anxiety
,
depres-
sion
, or other psychiatric illness. The
condition affects the sufferer's ability to
cope with everyday life.
nervous energy
A nontechnical term
for the increased drive and activity of
individuals who are always restless,
anxious, and on the go.
nervous habit
A nontechnical term for
a minor repetitive movement or activity.
Sometimes a nervous habit consists of
involuntary twitches and facial tics,
such as in
Giles de la Tourette's syn-
drome
and some forms of
dyskinesia.
Voluntary nervous habits, such as
nail-
biting
and
thumb-sucking
, are common
in young children.
All nervous habits increase during
periods of tension or anxiety, and may
be severe in some forms of
depression
,
anxiety disorder
, or drug withdrawal.
nervous system
The body system that
gathers and stores information and is in
overall control of the body.
NERVOUS SYSTEM
Optic nerve
Facial nerve
Vagus nerve
Cerebrum
of brain
Skull
Cerebellum
Spinal cord
fe-Ä cm
Sp,nal
nerve
< ;> T V r
^
\ A
Radial
nerve
Ulnar
nerve
Femoral ,
nerve
Superficial
peroneal
Deep__
peroneal
nerve
Medial dorsal
cutaneous
nerve _________
Median
nerve
Common
peroneal
nerve
Tibial
nerve
Dorsal
digital
nerves
N
395
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