sensation, but are usually painless. As
the tumour grows, it may develop into
an ulceror a deep fissure, which may
bleed and erode surrounding tissue.
Diagnosis is based on a biopsy.Treat-
ment consists of surgery, radiotherapy,
or both. Extensive surgery may cause
facial disfigurement and problems with
eating and speaking, which may require
reconstructive surgery. Radiotherapy
sometimes damages the salivary glands
(see mouth, dry).
When mouth cancer is detected and
treated early, the outlook is good.
mouth, dryThe result of inadequate
production of saliva. Dry mouth is usu-
ally a temporary condition caused by
fear, infection of a salivary gland, or the
action of anticholinergic drugs.
Rarely, permanent dry mouth may
occur as part of Sjögren’s syndrome or
from radiotherapyto treat mouth cancer.
Dryness usually causes difficulty in
swallowing and speaking, interference
with taste, and tooth decay (see caries,
dental). It may be relieved by spraying the
inside of the mouth with artificial saliva.
mouth-to-mouth resuscitationSee
artificial respiration.
mouth ulcerAn open sore caused by a
break in the mucous membranelining
the mouth. The ulcers are white, grey, or
yellow spots with an inflamed border.
The most common types are aphthous
ulcers (see ulcer, aphthous) and ulcers
caused by theherpes simplex virus. A
mouth ulcer may be an early stage of
mouth cancer and may need to be
investigated with a biopsyif it fails to
heal within a month.
mouthwashA solution for rinsing the
mouth. Many only leave the mouth feel-
ing fresh and remove loose food debris
from the teeth. Some, such as those con-
taining hydrogen peroxide, can help to
clean the teeth if the gums are too tender
for proper toothbrushing, as in some
types ofgingivitis. Those containing
chlorhexidineare effective against plaque
when routine dental hygiene is impossi-
ble. Fluoride mouthwashes help to
prevent tooth decay (see caries, dental),
and a mouthwash of warm salt water
can help to ease painful inflammation
caused by tooth disorders. Antiseptic
mouthwashes intended to combat hali-
tosisare usually ineffective because they
do not treat the cause of the problem.
movementBodily movements include
skeletal movements and movements of
soft tissues and body organs. All move-
ment is brought about by the actions of
muscles and may be voluntary, involun-
tary, or a reflexaction.
All voluntary skeletal movements are
initiated in the part of the cerebrum
(main mass of the brain) called the
motor cortex. Signals are sent down the
spinal cordalong nerve fibres, and from
there along separate nerve fibres to the
appropriate muscles. Control relies on
information supplied by sensory nerve
receptors, in the muscles and else-
where, that record the position of the
different parts of the body and the
amount of contraction in each muscle.
This information is integrated in spe-
cific regions of the brain (including the
cerebellumand basal ganglia) that con-
trol the coordination, initiation, and
cessation of movement.
Skeletal movements can also occur as
simple reflexes in response to certain
sensory warning signals; the movement
is automatic and less controlled, involv-
ing far fewer nerve connections.
Some body movements do not involve
the skeleton. For example, eye and
tongue movements are brought about
by contractions of muscles that are
attached to soft tissues. These move-
ments may be voluntary or reflex.
Movements of the internal organs are
involuntary; they include the heartbeat
and peristalsis.
moxibustionA form of treatment, often
used in conjunction with acupuncture,
in which a cone of wormwood leaves
(moxa) or certain other plant materials
is burned just above the skin to relieve
internal pain.
moxisylyteA vasodilator drugused in
the treatment of Raynaud’s disease. Side
effects include nausea, diarrhoea, hot
flushes, headache, and dizziness.
MRIThe abbreviation for magnetic res-
onance imaging. MRI is a diagnostic
technique that produces cross-sectional
or 3-dimensional images of organs and
other body structures.MOUTH, DRY MRI
M