impaction, dental) and alveolectomy.
More complicated oral surgeryincludes
orthognathic surgeryto correct deformi-
ties of the jaw; repair of a broken jaw;
plastic surgery to correct cleft lip and
palate; and the removal of some non-
cancerous tumours from the mouth.
oral syringeA device used to administer
liquid medicines by mouth, especially to
young children. Small, accurately mea-
sured doses of the drug are drawn into
the syringe via a plunger and squirted
on to the inside of the cheek.orbitThe socket in the skullcontaining
the eyeball, protective fat, blood ves-
sels, muscles, and nerves. The optic
nervepasses into the brainthrough an
opening in the back of the orbit.
A severe blow to the face may fracture
the orbit, but the eyeball is often
undamaged as it can move back into the
socket. Fractures often heal without
treatment, but some cause deformity
and require corrective surgery. Rarely,
bacterial infection spreads from a sinus
or the face to cause orbital cellulitis.
orbital cellulitisBacterial infection of
the tissues within the eye socket, or
orbit. Infection is potentially serious as
it may spread to the brain. Treatment is
with high doses of antibiotic drugs.
orchidectomyThe surgical removal of
one or both of the testes. Orchidectomy
may be performed for testicular cancer
(see testis, cancer of) or gangrene due totorsion (see testis, torsion of), or to
reduce production of testosteronein the
treatment of cancer of the prostate
gland (see prostate, cancer of). Removal
of one testis does not affect sex drive,
potency, or the ability to have children.
orchidopexyAn operation to bring
down an undescended testis (see testis,
undescended) into the scrotum. Orchi-
dopexy is usually performed at age 2–5
to reduce the risk of later infertilityor
testicular cancer (see testis, cancer of).
orchitisInflammation of a testis. Orchitis
may be caused by the mumpsvirus, par-
ticularly if infection occurs after puberty.
Swelling and severe pain in the affected
testis are accompanied by high fever. In
epididymo-orchitis, the tube that carries
sperm from the testis is also inflamed.
Treatment is with analgesic drugsand
ice-packsto reduce swelling; antibiotic
drugsmay be given, but not for mumps
orchitis. The condition usually begins
to subside within 7 days but is occasion-
ally followed by shrinking of the testis.
orfA skin infection occasionally transmit-
ted to humans from sheep. Caused by a
poxvirus, orf usually produces a single
persistent, fluid-filled blister on the arm
or hand. The antiviral drug idoxuridine
may hasten recovery. Large lesionsmay
be removed surgically.
organA collection of various tissues
integrated into a distinct structural unit
to perform specific functions. For exam-
ple, the brain consists of nerve tissue
and support tissue organized to receive,
process, and send out information.
organ donationThe agreement of a
person (or his or her family) to surgical
removal of one or more organs for use in
transplant surgery. Most organs for trans-
plantation, such as the heart, lungs, liver,
and kidneys, are removed immediately
after death, often in intensive care units
where heart and lung function is some-
times maintained by machine afterbrain
deathbeen certified. Compatible living
donors may also be able to give a kidney
(see tissue-typing). People can facilitate
use of their organs after death byinform-
ing relatives and carrying a donor card.
(See also corneal graft; heart–lung trans-
plant; heart transplant; heart-valve surgery;
kidney transplant; liver transplant.)ORAL SYRINGE ORGAN DONATIONO
Syringe angled
so that tip is
towards cheekORAL SYRINGEUSING AN ORAL SYRINGE