causing pain, numbness, and, in severe
cases, gangrene. Polyarteritis nodosa, a
serious autoimmune disorder, can affect
arteries in any part of the body, espe-
cially the heart and kidneys. Temporal
arteritisaffects arteries in the scalp and
may affect the eyes. A rare type of arter-
itis is Takayasu’s arteritis, which is
thought to be an autoimmune disorder.
This usually affects young women and
involves the arteries that branch from
the aortainto the neck and arms.
arteryA blood vessel that carries blood
away from the heart. Systemic arteries
carry blood pumped from the left ventri-
cle of the heart to all parts of the body
except the lungs. The largest systemic
artery is the aorta, which emerges from
the left ventricle; other major systemic
arteries branch off from the aorta. The
pulmonary arteries carry blood from the
right ventricle to the lungs.
Arteries are tubes with thick, elastic,
muscular walls able to withstand the
high pressure of blood flow. The structure
of arteries helps to even out the peaks
and troughs of blood pressure caused
by the heartbeat, so that the blood is
kept flowing at a relatively constant pres-
sure. (See also arteries, disorders of.)
arthralgiaPain in the joints or a single
joint. (See also arthritis; joint.)
arthritisInflammation of one or more
joints, with pain, swelling, and stiffness.
There are several different types of
arthritis, each having different charac-
teristics. The most common form is
osteoarthritis, which most often involves
the knees, hips, and hands and usually
affects middle-aged and older people.
Cervical osteoarthritisis a form of osteo-
arthritis that affects the joints in the
neck. Rheumatoid arthritisis a damaging
condition that causes inflammation in
the joints and other body tissues such
as the membranous heart covering,
lungs, and eyes. The disorder has dif-
ferent effects in children (see juvenile
chronic arthritis). Ankylosing spondylitis
is another persistent form of arthritis
that initially affects the spine and the
joints between the base of the spine
and the pelvis. Other tissues, such as the
eyes, may also be affected. Eventually,
the disorder may cause the vertebrae
(bones of the spine) to fuse. Reactive
arthritistypically develops in suscepti-
ble people following an infection, most
commonly of the genital tract or intes-
tines. Goutand pseudogoutare types of
arthritis in which crystals are deposited
in a joint, causing swelling and pain.
Septic arthritisis a relatively rare condi-
tion that can developwhen infection
enters a joint either through a wound or
from the bloodstream.
Diagnosis of particular types of arthri-
tis is made from blood testsand, in
some cases, microscopic examination
of fluid from the affected joint. X-rays or
MRIcan indicate the type and extent
of joint damage.
Physiotherapyand exercises can help
to minimize the effects of arthritis, and
there are specific treatments for some
types, such as antibiotic drugsfor septic
arthritis. In severe cases, one or more
joints may need arthroplasty(replace-
ment with an artificial substitute) or
arthrodesis(fusion of the bones).
arthrodesisA surgical procedure in
which the 2 bones in a diseased joint are
fused to prevent the joint from moving,
which relieves pain. Arthrodesis is perfor-
med if a joint is painful or unstable and
other treatments such as drugs or arthro-
plastyhave failed or are inappropriate.
arthrographyA diagnostic technique
in which the interior of a damaged joint
is X-rayedafter injection of a radiopaque
solution. It is being replaced by MRI,
ultrasound scanning, and arthroscopy.
arthrogryposisSee contracture.
arthropathyDisease of the joints.
arthroplastyReplacement of a joint or
part of a joint by metal or plastic com-
ponents. A hip replacementis one of the
most common operations of this type,ARTERY ARTHROPLASTY
A
Outer layerMuscle
layerElastic
layerARTERYInner
lining