CRANIAL NERVES
C
of the
ovaries
or
testes).
The condition
is associated w ith deficiencies of
lutein-
izing hormone
and
growth hormone.
cranial nerves
Twelve pairs of
nerves
that emerge from
the underside of the
brain.
Each of the
cranial nerves has a number as well as
a name; the numbers are used to indi-
cate the sequence in w hich the nerves
emerge from the brain.
Certain cranial nerves prim arily send
sensory
information
from
the
ears,
nose,
and
eyes to the
brain. These
nerves
are
the
vestibulocochlear nerve
(hearing and balance),
olfactory nerve
(smell), and
optic nerve
(vision). Other
cranial nerves carry impulses that move
the muscles in the head and neck. They
are the
oculomotor nerve,
the
trochlear
nerve,
and the
abducent nerve
(producing
eye movements), the
spinal accessory
nerve
(producing
head and shoulder
movements), and
hypoglossal nerve
(pro-
ducing tongue movements).
Some cranial nerves have both senso-
ry and motor functions. They are the
facial nerve
(facial
expressions,
taste,
and the secretion of saliva and tears),
the
trigeminal nerve
(facial sensation and
jaw movements), and the
glossopharyn-
geal nerve
(taste and swallowing). The
vagus nerve
has branches to all the main
digestive organs, as well as to the heart
and the lungs. It is a major component
of the
parasympathetic nervous system
,
w hich is concerned with maintaining
automatic
body
functions
such
as
breathing, the heartbeat, and digestion.
craniopharyngioma
A rare, non-hormone-secreting tumour
of the
pituitary gland
.
Symptoms of a
craniopharyngioma may include head-
aches, vomiting, and defective vision. If
the tumour develops in childhood, the
child’s growth may be stunted and sex-
ual development may not occur.
Craniopharyngiomas are usually sur-
gically removed. If left untreated, they
may cause permanent brain damage.
craniosynostosis
The premature closure of one or more
of the joints (sutures) between the
skull
bones in infants. If all of the joints are
involved, the growing
brain
may be
compressed and there is a risk of brain
damage due to the increased pressure
inside the skull. If the abnormality is
localized, the head may be deformed.
Craniosynostosis may occur before
birth and may be associated with other
birth defects
.
It may also occur in an
otherwise healthy baby, or in a baby
with a disorder such as
rickets
.
CRANIAL NERVES
All but two of the cranial nerve pairs connect with nuclei in
the brainstem. The olfactory and optic nerves, in contrast,
link directly with parts of the cerebrum. The nerves emerge
through openings in the cranium (skull); many then divide
into branches.
Certain cranial nerves are principally concerned with
transmitting sensory information from organs such as the
ears, nose, and eyes to the brain. Others carry impulses that
move the tongue, eyes, and facial (and other) muscles, or
stimulate glands such as the salivary glands. A few nerves
have both sensory and motor functions. The
10
th, or
vagus
nerve
,
is one of the most important parts of the
parasympathetic nervous system
,
and has branches to the
main digestive organs, the heart, and the lungs.
1
Olfactory nerve
Smell
2
Optic nerve
Vision
3, 4, 6
Oculomotor,
trochlear, and
abducent
nerves
Eye movements
5
Trigeminal
nerve
Facial sensation
and jaw
movements
7
Facial nerve
Facial
expressions
and taste
}fy
’'411
Ay;
\ f :'N
8
Vestibulo-
cochlear nerve
Hearing and
balance
9
Glossopharyn-
geal nerve
Taste and throat
sensations
10
Vagus nerve
Breathing,
circulation,
and digestion
11
Spinal
accessory nerve
Movements of
neckand back
muscles
12
Hypoglossal
nerve
Tongue
movements
202
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