CALF MUSCLES
time of
ovulation
(the release of an egg
from a wom an’s ovary). This time is
calculated on the basis of the length of
her previous menstrual cycles. The cal-
endar method is unreliable because a
woman’s
menstrual
cycle
may
vary.
There
are
now
more
scientific
and
effective contraceptive methods of this
type (see
contraception, natural methods
) .
calf muscles
The muscles extending from the back
of the knee to the heel. The gastrocne-
mius muscle starts behind the knee and
forms
the
bulky
part
of the
calf;
beneath it lies the soleus muscle w hich
starts at the back of the
tibia
(shin).
These two muscles join to form the
Achilles tendon
,
w hich connects them to
the heel. Contraction of the calf mus-
cles pulls the heel up and is important
in walking, running, and jumping.
calf pain
Various disorders may be responsible
for pain in the calf. Common causes
include
cramp
,
muscle strain, and
scia-
tica
(inflammation of the sciatic nerve).
More rarely, pain in the calf muscles
may be due to blood clots in leg veins
(see
thrombosis, deep vein
) .
This disorder
is a particular risk if a person has been
im m obile for a long time - for exam-
ple, after surgery or during a long
journey by air. Another possible prob-
lem is
claudication
(cramping pain often
due to narrowing of the arteries). In
this last condition, pain is often caused
by walking and relieved by rest.
caliper splint
An
orthopaedic
device that corrects or
controls a deformed leg or supports a
leg weakened by a muscular disorder,
allowing an affected person to stand
and walk. For example, a person who
has lost the ability to flex the foot
upward and, as a result, drags the toes
on the ground with each step can be
fitted with a splint that keeps the foot
permanently at right angles to the leg,
thereby allowing walking.
A caliper splint consists of one or
two vertical metal rods attached to
leather or metal rings that are worn
around
the
affected
limb.
A
splint
extending just below the knee is suffi-
cient to control the position of the
ankle. Longer splints may be jointed to
allow movement of the knee.
callosity
See
callus, skin.
callus, bony
A diffuse growth of new, soft bone that
forms as part of the healing process in
a
fracture
.
As healing continues, the cal-
lus is replaced by harder bone, and the
original shape of the bone is restored.
callus, skin
An area of thickened skin, usually on
the hands or feet, caused by regular or
prolonged pressure or friction. A
corn
is
a callus on a toe. If corns are painful,
the thickened skin can be pared away
by a chiropodist using a scalpel.
caloric test
A method of finding out whether the
labyrinth
in the inner ear is diseased. A
caloric test may be performed as part of
investigations into
vertigo
(dizziness)
and hearing loss.
The outer-ear canal is briefly flooded
with water of different temperatures,
above and below normal body temp-
erature. This flooding sets up convection
currents in the semicircular canals in
the inner ear. If the labyrinth is normal,
nystagmus
(rapid reflex flickering of the
eyes) occurs for a predictable period. If
the labyrinth is diseased, this response
is either absent or reduced. The pres-
ence and duration of nystagmus may be
observed directly or recorded electri-
cally using
electronystagmography.
calorie
A unit of energy One calorie is the
amount of energy that is needed to
raise the temperature of 1
gram of
water by
1
°C.The term “ calorie” is also
used in medicine and
dietetics
to mean
“kilocalorie” , w hich is a larger unit of
energy equal to 1,000 calories.
Norm ally when a person’s calorie
intake matches the amount of energy
expended, body weight remains con-
stant. If intake
exceeds
expenditure,
weight is usually gained; if expenditure
exceeds intake, weight is usually lost. In
general, fats contain more calories than
proteins or carbohydrates.
Energy
can
also
be
measured
in
joules:
1
calorie equals
4.2
joules. (See
also
calorimetry; diet and disease.)
calorie requirements
See
energyrequirements.
calorimetry
The measurement of the
calorie
(ener-
gy)
value
of foods
or
the
energy
expenditure
of a
person.
In
direct
calorimetry, a small measure of food is
burned up inside a sealed container,
w hich is immersed in water. The resul-
tant rise in water temperature is used to
calculate the calorie value.
Energy production in humans can be
measured by oxygen uptake. Every litre
of oxygen taken into the body pro-
duces
4.8
kilocalories of energy The
level of energy production is calculated
by comparing the percentage of oxy-
gen in air that is inhaled and exhaled.
Calpol
A brand name for paediatric prepara-
tions
containing
the
analgesic drug
(painkiller)
paracetamol
.
camouflaging preparations
Creams or powders that are applied to
the skin to conceal skin disfigurements,
such as
birthmarks
and scars.
Campbell de Morgan’s spot
A small (
1-3
m m ), bright red, domed
spot, also known as a cherry angioma,
that appears on the trunk or limbs. A
Campbell de Morgan’s spot is a type of
haemangioma
(a
noncancerous
blem-
ish). The spots are harmless. They are
138
previous page 137 BMA A Z Family Medical Encyclopedia   2004 read online next page 139 BMA A Z Family Medical Encyclopedia   2004 read online Home Toggle text on/off