TRIFLUOPERAZINE
TROCHLEAR NERVE
T
trifluoperazine An
antipsychotic drug
used to treat
schizophrenia.
trigeminal nerve The 5th
cranial nerve.
A trigeminal nerve arises from the
brain-
stem.
Both nerves divide into 3 branches
that supply sensation to the face, scalp,
nose, teeth, lining of the mouth, upper
eyelid,
sinuses
, and the front portion of
the tongue. They stimulate
saliva
and
tear
production and contraction of
jaw
muscles for chewing.
trigeminal neuralgia A disorder of the
trigeminal nerve
in which brief episodes
of severe, stabbing pain affect the
cheek, lips, gums, or chin on
1
side of
the face. The disorder usually occurs
over age 50. Pain may come in bouts
that last for weeks at a time. The cause
is uncertain, and pain is often brought
on by touching the face, eating, drink-
ing, or talking.
Analgesic drugs
may be
tried, but often,
carbamazepine
is more
effective. If this fails, surgery may help.
trigger finger Locking of
1
or several
fingers in a bent position due to inflam-
mation of the sheath enclosing the
tendon
of the affected finger. The finger is usually
tender at the base and slightly swollen
over the tendon. Treatment involves
local injection of a
corticosteroid drug
or, if this is unsuccessful, surgery.
triglyceride A type of simple fat (see
fats and oils
) made up of a molecule of
glycerol
and 3 molecules of fatty acids.
Triglycerides are the main type of fat
found in stores of body fat.
trimeprazine Also called alimemazine.
An
antihistamine drug
used to relieve
itching in allergic conditions, and as a
premedication
in children. Side effects
are typical of antihistamines.
trimester A period of 3 months; human
pregnancy
is conventionally divided into
3 trimesters.
trimethoprim An
antibacteria drug
used
to treat a range of infections, most com-
monly those of the urinary tract. Possible
side effects include rash, itching, nausea,
vomiting, diarrhoea, and a sore tongue.
trimipramine A tricyclic
antidepressant
drug
used to treat
depression
accompa-
nied by
anxiety
or
insomnia.
Possible side
effects include dry mouth, blurred vision,
dizziness, constipation, and nausea.
triple vaccine See
DPT vaccination.
triprolidine An
antihistamine drug
that
is used to treat
allergy,
as an ingredient
of cough and cold remedies, and to
treat or prevent allergic reactions to
certain foods or
blood transfusions.
Pos-
sible side effects of triprolidine include
dry mouth, dizziness, difficulty in pass-
ing urine, and
hyperactivity.
trismus Involuntary contraction of the
jaw muscles, which causes the mouth to
become tightly closed. Commonly known
as lockjaw, it may occur as a symptom
of
tetanus
,
tonsillitis
,
mumps
, or acute
ulcerative
gingivitis
and other dental
problems affecting the back teeth. Treat-
ment is of the underlying cause.
trisomy The presence of an extra
chro-
mosome
within a person's cells, making
3 of a particular chromosome instead of
the usual 2. A fault during
meiosis
to
form egg or sperm cells leaves an egg or
sperm with an extra chromosome. When
the egg or sperm takes part in fertiliza-
tion, the resulting embryo inherits an
extra chromosome in each of its cells.
The most common
trisomy is of
chromosome 21
(Down's syndrome).
Trisomy 18 (Edward's syndrome) and
trisomy 13 (Patau's syndrome) are less
common; trisomy
8
and trisomy
22
are
very rare. Partial trisomy, with only part
of a chromosome in triplicate, also
occurs. Full trisomies cause abnorma-
lities such as skeletal and heart defects
and
learning
difficulties.
Except
in
Down's syndrome, babies usually die in
early infancy. The effects of partial tri-
somies depend on the amount of extra
chromosomal material present.
Diagnosis is made by
chromosome
analysis
of cells, which may be obtained
from the fetus by
amniocentesis
or after
the birth. There is no specific treatment.
Parents of an affected child should seek
genetic counselling
.
trisomy 2 1 syndrome Another name
for
Down's syndrome
.
trochlear nerve The 4th
cranial nerve.
The 2 trochlear nerves arise in the
brainstem
,
1
on each side of the mid-
brain,
and
enter
the
eye
sockets
through gaps in the skull bones. Each
trochlear nerve controls
1
of the
2
sup-
erior oblique muscles, which rotate the
eyes downwards and outwards.
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