recovery, patients often feel depressed,
lack energy, and have daytime sleepiness.
monorchismThe presence of only one
testis. The most probable causes are
surgery (see orchidectomy) and congen-
italabsence of the testis.
monosodium glutamateA food addi-
tivethat is used as a flavour enhancer
and seasoning. Monosodium glutamate
(MSG) is the sodium salt of an amino
acid. A short-lived illness involving pain
in the neck and chest, palpitations, feel-
ing hot, and a headache may occur in
some people after eating food to which
large amounts of MSG have been added.
mons pubisThe rounded swelling over
the front of the pubic bone. The mons
pubis, which becomes covered with hair
at puberty, is formed by a pad of fatty
tissue under the skin.
Monteggia’s fractureFracture of the
ulnajust below the elbow, with disloca-
tion of the radius from the elbow joint.
montelukastA specific leukotriene re-
ceptor antagonist drugthat is used in
the management of asthma. It is not
used to treat acute attacks.
mood disordersDisorders in which the
emotions are affected: mania, depression,
and manic–depressive illness.
moon faceRounded facial appearance
that is a feature of Cushing’s syndrome.
morbid anatomyAlso called pathologi-
cal anatomy, the study of the structural
changes that occur in body tissues as a
result of disease, especially the changes
visible to the naked eye.
morbidityThe state or condition of
being diseased. In medical statistics,
the morbidity ratio is the proportion of
diseased people to healthy people in a
particular community.
morbilliAnother name for measles.
morning-after pillSee postcoital con-
traception.
morning sickness See vomiting in
pregnancy.
morphineAn opioid analgesic drugde-
rived from the opium poppy. Morphine
is given to relieve severe pain caused by
myocardial infarction, major surgery,
serious injury, and cancer.
Morphine blocks the transmission of
pain signals at sites called opiate recep-
tors in the brainand spinal cord. The
drug also induces a sense of well-being
or euphoria. Side effects include drow-
siness, dizziness, constipation, nausea,
vomiting, and confusion. Long-term use
of morphine may lead to drug depen-
dence, with severe flu-like symptoms
when the drug is withdrawn (see with-
drawal syndrome).
morphoeaA condition in which one or
more hard, flat patches develop on the
skin. It is a type of sclerodermabut is
confined to the skin. Although harmless,
the condition can be disfiguring.
mortalityThe death rate, which is the
number of deaths per 100,000 (or 10,000
or 1,000) of the population per year.
Mortality is often calculated for specific
groups. For example, infant mortality
measures the deaths of live-born infants
during the 1st year of life.
Standardized mortality allows compari-
son of the death rate in, for example, an
occupational or socioeconomic group
with that for the entire population. (See
also life expectancy; maternal mortality.)
morulaA stage in the development of
an embryoafter fertilization. The fertil-
ized egg divides repeatedly as it travels
down the fallopian tube. When it forms a
ball of cells, it is called a morula.
mosaicismThe presence of 2 or more
groups of cells containing different
genetic material within one person.
Some people with syndromes caused
by chromosomal abnormalities(such as
Down’s syndrome and Turner’s syn-
drome) have mosaicism. Depending on
the proportion of abnormal cells and
the type of abnormality, they range from
looking physically normal to having fea-
tures typical of the syndrome.
mosquito bitesMosquitoes are flying
insects found throughout the world.
The females bite humans or animals to
obtain blood, which they need to pro-
duce eggs. The males do not bite. A
doctor should be consulted if there is a
severe skin reaction to a mosquito bite.
As well as being irritating, mosquito
bites can also transmit diseases. The
main disease-transmitting mosquitoes
belong to 3 groups: ANOPHELES(which
transmits malaria), AEDES(which carries
yellow fever), and CULEX(which trans-
mits filariasis).MONORCHISM MOSQUITO BITES
M