MECONIUM
MEDULLA
intussusception
or
volvulus
of the small
intestine. Diagnosis of Meckel's divertic-
ulum may be made by using technetium
radionuclide scanning
.
If complications
occur, they are treated by surgical re-
moval of the diverticulum.
meconium
The thick, sticky, greenish-
black faeces passed by infants in the
first day or two after birth. It consists of
bile
, mucus, and shed intestinal cells.
Occasionally, the fetus passes meco-
nium into the
amniotic fluid
in the
uterus. This is more common in babies
who experience
fetal distress
during
labour or who are over 40 weeks' gesta-
tion. Meconium in the amniotic fluid
may be inhaled when the baby starts to
breathe, sometimes blocking the air-
ways and damaging the lungs.
In some babies with
cystic fibrosis
, the
meconium is so thick and sticky that
it blocks the intestine (see
intestine,
obstruction
of).
medial
A medical term that means “sit-
uated towards the midline of the body”.
Less commonly, the term refers to the
middle layer of a body structure.
median nerve
One of the main nerves
of the arm. It is a branch of the
brachial
plexus
and runs down the arm from the
shoulder into the hand. The median
nerve controls the muscles that carry
out bending movements of the wrist,
fingers, and thumb, and that rotate the
forearm palm-inwards. The nerve also
conveys sensations from the thumb and
first 3 fingers, and from the region of
the palm at their base.
Damage to the nerve may result from
injury to the shoulder, a
Colies' fracture
just above the wrist, or pressure on the
nerve where it passes through the wrist
(
carpal tunnel syndrome
).
Symptoms of
damage include numbness and weak-
ness in areas controlled by the nerve.
mediastinoscopy
Investigation of the
mediastinum
by means of an
endoscope
inserted through an incision in the neck.
Mediastinoscopy is used mainly to
perform a
biopsy
of a
lymph node
.
The
sample is removed by tiny blades on
the endoscope.
mediastinum
The membranous parti-
tion between the lungs and the other
structures within the chest cavity. These
structures include the
heart
and associ-
ated blood vessels,
trachea
,
oesophagus
,
thymus
gland,
lymph nodes
, lymphatic
vessels, and nerves.
medication
Any substance prescribed to
treat disease. (See also
drug; medicine.)
medicine
The study of human diseases,
their causes, frequency, treatment, and
prevention. The term is also applied to
a substance prescribed to treat illness.
medicolegal
Relating to aspects of med-
icine and law that overlap. Among the
matters on which medicolegal experts
advise are the laws concerning damages
for injuries due to medical negligence
or malpractice, evidence concerning the
extent of injury in a civil action, the use
of paternity tests, the mental compet-
ence of people who have drawn up wills,
and restrictions on the mentally ill.
Medicolegal issues also include an
individual's right to die (see
brain death
;
euthanasia; living will);
the necessity for
informed
consent
to any surgical pro-
cedure; the legal aspects of
artificial
insemination, in vitro fertilization, steril-
ization,
and
surrogacy;
and a patient's
right to
confidentiality
concerning his or
her illness. (For the medical aspects of
criminal law, see
forensic medicine.)
meditation
Concentrating on an object,
a word, or an idea with the aim of induc-
ing an altered state of consciousness.
At its deepest level, meditation can
resemble a trance. More commonly, it is
a calming therapy and can be a way of
reducing stress levels and treating stress-
related disorders. A common form of
meditation practised in the west is tran-
scendental meditation (TM).
medroxyprogesterone
A
progestogen
drug
used to treat
endometriosis
and
certain types of
breast cancer
and uter-
ine cancer (see
uterus, cancer of
). It is
sometimes used to treat menstrual dis-
orders such as
amenorrhoea
(absence
of menstruation). Medroxyprogesterone
can also be used as a contraceptive,
administered by injection at 3-monthly
intervals (see
contraception, hormonal
methods of
). Possible adverse effects
include weight gain, swollen ankles, and
breast tenderness.
medulla
The innermost part of an organ
or other body structure; for example,
359
previous page 357 BMA Illustrated Medical Dictionary read online next page 359 BMA Illustrated Medical Dictionary read online Home Toggle text on/off