The next 2 or 3 pairs of “false ribs” con-
nect indirectly to the sternum by means
of cartilage attached to the cartilage of
the ribs above. Between and attached
to the ribs are thin sheets of muscle
(intercostal muscles) that act during
breathing. The spaces between the ribs
also contain nerves and blood vessels.
ribavirinAn antiviral drug, also called
tribavirin, used to treat children with
viral bronchiolitiscaused by respiratory
syncytial virus. Adverse effects are rare.
rib, fracture ofFractureof a rib may
be caused by a fall or blow, or by stress
on the ribcage, such as that produced
by prolonged coughing. The fracture of
a rib causes severe pain, which may be
relieved by analgesic drugsor by an
injection of a local anaesthetic.
riboflavinThe chemical name of vitamin
B 2 (see vitamin B complex).
ricketsA disease caused by nutritional
deficiency that causes bonedeformities
in childhood. Bones become deformed
because inadequate amounts of calcium
and phosphateare incorporated into
them as they grow. The most common
cause is vitamin Ddeficiency. It also
occasionally develops as a complication
of malabsorptionand may also occur in
rare forms of kidney and liver disease.
Rickets due to dietary deficiency is
treatedwith supplements. The deformi-
ties usually disappear as the child grows.
Rickets occurring as a complication of a
disorder is treated according to the cause.
rickettsiaA type of small bacteriathat
can multiply only by invading other living
cells. They are mainly parasites of arthro-
pods such as ticks, lice, fleas, and mites.Human diseases caused by
rickettsiae include Q fever,
Rocky Mountain spotted
fever, and typhus.
rifampicinAn antibacter-
ial drugused mainly to
treat tuberculosis. It is also
used to treat leprosyand
legionnaires’ disease. The
drug is usually prescribed
with other antibacterials
because some strains of
bacteria develop resistance
if it is used alone.
Side effects include harm-
less, orange-red discoloration of the urine,
saliva, and other body secretions, muscle
pain, nausea, vomiting, diarrhoea, jaun-
dice, flu-like symptoms, rash, and itching.
The drug interferes with the action of
oral contraceptives.
rigidityIncreased tone in one or more
muscles, causing them to feel tight; the
affected part of the body becomes stiff
and inflexible. Causes include muscle
injury, arthritisin a nearby joint, a neu-
rological disorder, or stroke. Rigidity of
the abdominal muscles is a sign of peri-
tonitis. (See also spasticity.)
rigorA violent attack of shivering, often
associated with a fever. Rigor may also
refer to stiffness or rigidity of body tis-
sues, as in rigor mortis.
rigor mortisThe stiffening of muscles
that starts 3–4 hours after death. It is usu-
ally complete after about 12 hours; the
stiffness then disappears over the next
48–60 hours. Physical exertion before
death makes rigor mortis begin sooner.
The sooner rigor mortis begins, the
quicker it passes. These facts are used
to help assess the time of death.
ringing in the earsSee tinnitus.
ringwormA popular name for certain
fungal skin infections. Ringworm causes
ring-shaped, reddened, scaly, or blistery
patches on the skin. (See also tinea.)
ritodrineA drug used to prevent or delay
premature labour (see prematurity). Side
effects may include tremor, chest pain,
palpitations, nausea, vomiting, and flushing.
river blindnessSee onchocerciasis.
RNAThe abbreviation for ribonucleic
acid. RNA andDNA carry inherited
genetic instructions. In animal and plantRIBAVIRIN RNAR
RIBScapulaClavicleRibVertebral column
Floating ribCostal cartilageSternumRibcage