peripheral nervous system. CLOSTRIDIUM
BOTULINUMproduces spores that resist
boiling, salting, smoking, and some
forms of pickling. These spores, which
multiply only in the absence of air,
thrive in canned or improperly pre-
served food. Ingestion of even minute
amounts of toxin can lead to severe
poisoning. Symptoms first occur within
8–36 hours and include difficulty in
swallowing and speaking, vomiting, and
double vision. Prompt treatment is
vital. In infants, the toxin can form with-
in the body after the ingestion of foods
contaminated with the bacterium, such
as honey. (See also food poisoning.)
bovine spongiform encephalopathy
(BSE)A neurological disorder in cattle
that can be transmitted to humans
through consumption of infected meat,
causing Creutzfeldt–Jakob disease. (See
also encephalopathy.)
bowelA common name for the large
and/or small intestines.
bowel movements, abnormalSee
faeces,abnormal.
bowel soundsSounds made by the pas-
sage of air and fluid through the intestine.
Absent or abnormal bowel sounds may
indicate a disorder. Those that are audi-
ble without a stethoscope are known as
borborygmi and are a normal part of
the digestive process, but they may be
exaggerated by anxiety and some disor-
ders of the intestine.
Bowen’s diseaseA rare skin disorder
that sometimes becomes cancerous. A
flat, regular-shaped, patch of red, scaly
skin forms, most commonly on the
face or hands. The diseased skin is
removed surgically or destroyed by
freezing or cauterization.
bowlegAn outward curving of bones in
the legs that results in wide separation
of the knees when the feet are together.
Bowlegs are common in very young
children and are a normal part of de-
velopment. In most cases, the curve
straightens as the child grows. If the
bowing is severe, is on one side only, or
persists beyond the age of 6, a doctor
should be consulted. Surgery may be
needed. Rarely, leg deformity is a result
of bone disease, particularly rickets(a
vitamin D deficiency) in children.
brace, dentalSee orthodontic appli-
ances.
brace, orthopaedic An appliance worn
to support part of the body or hold it in
a fixed position. It may be used to correct
or halt the development of a deformity,
to aid mobility, or to relieve pain. (See
also caliper splint; corset; splint.)
brachial arteryThe arterythat runs
down the inner side of the upper arm,
between the armpit and the elbow.
brachialgiaPain or stiffness in the arm
that is often accompanied by pain, ting-
ling and/or numbness of the hands or
fingers, and weak hand grip. It may be a
symptom of underlying disorders such
as frozen shoulderor nerve compression
from cervical osteoarthritis.
brachial plexusA collection of large
nerve trunks that are formed from nerve
roots of the lower part of the cervical
spine (in the neck) and the upper part of
the thoracic spine (in the chest). These
nerve trunks divide into the musculocu-
taneous, axillary, median, ulnar, and radial
nerves, which control muscles in and re-
ceive sensation from the arm and hand.
Injuries to this plexus can cause loss of
movement and sensation in the arm.
In severe injuries, there may be dam-
age to both the upper and the lower
nerve roots of the brachial plexus, pro-
ducing complete paralysis of the arm.
Paralysis may be temporary if the
stretching was not severe enough to
tear nerve fibres. Nerve roots that have
been torn can be repaired by nerve
grafting, a microsurgeryprocedure. If a
nerve root has become separated from
the spinal cord, surgical repair will not
be successful. Apart from injuries, the
brachial plexus may be compressed by
the presence of a cervical rib(extra rib).
brachytherapySee interstitial radio-
therapy.
bradycardiaAn abnormally slow heart-
rate. Most people have a heart-rate of
between 60 and 100 beats per minute.
Many athletes and healthy people who
exercise regularly and vigorously have
slower rates. In others, bradycardia may
indicate an underlying disorder such as
hypothyroidismor heart block. Bradycar-
dia may also occur as a result of taking
beta-blocker drugs. Profound or suddenBOVINE SPONGIFORM ENCEPHALOPATHY BRADYCARDIA
B