Bma Illustrated Medical Dictionary

is continued for 6 weeks. Drug treat-
ment with tamoxifen or chemotherapy
may also be given.
masticationThe process of chewing
food. The canines and incisors (front
teeth) shear the food. The tongue then
pushes it between the upper and lower
premolars and molars (back teeth) to be
ground by movements of the lower jaw.
Salivais mixed with the food to help
break it down for swallowing.
mastitisInflammation of breast tissue,
usually caused by bacterial infection
and sometimes by hormonal changes.
Mastitis usually occurs when bacteria
enter the nipple during breast-feeding. It
can also be caused by changesin levels
of sex hormonesin the body – for exam-
ple, at the onset of puberty.
Mastitis results in pain, tenderness,
and swelling in one or both breasts.
Bacterial mastitis during breast-feeding
also causes redness and engorgement
and may result in a breast abscess.
Mastitis caused by infection is treated
with antibiotic drugs and analgesic
drugs, and by expressing milkto relieve
engorgement. Mastitis caused by hor-
mone changes usually clears up in a few
weeks without treatment.
mastocytosisAn unusual condition in
which itchy, irregular, yellow or orange-
brown swellings occur on the skin, most
commonly on the trunk. Mastocytosis
may also affect body organs, including
the liver, spleen, and intestine, and it
may cause symptoms such as diarrhoea,
vomiting, and fainting. Very rarely, the

condition leads to

anaphylactic shock,

which can be fatal.

The condition usu-

ally begins in the 1st

year of life and clears

up by adolescence.

Antihistamine drugs

may be helpful in

relieving symptoms

of mastocytosis.

mastoid boneThe

lower part of the

temporal bone in

the skull. It has a

projection, known

as the mastoid pro-

cess, which can be felt behind the ear.

The mastoid bone is honeycombed with

air cells. These are connected to a cavity

called the mastoid antrum, which leads

into the middle ear. Infections of the

middle ear (see otitis media) occasion-

ally spread through the mastoid bone

to cause acute mastoiditis.

mastoiditisInflammation of the mastoid

bonein the skull. The disease is caused

by infection spreading from the middle

ear (see otitis media) to the air cells in

the mastoid bone through a cavity

called the mastoid antrum.

Mastoiditis causes earache and severe

pain, swelling, and tenderness behind

the ear. There is usually also fever, a

creamy discharge from the ear, progres-

sive hearing loss, and displacement of

the outer ear. If the infection spreads, it

may lead to meningitis, a brain abscess,

blood clotting in veins within the brain,

or facial palsy.

Treatment is with antibiotic drugs. If

the infection persists, an operation

known as a mastoidectomy may be car-

ried out to remove the infected air cells.

masturbationSexual self-stimulation,

usually to orgasm. Massaging the penis

or the clitoriswith the hand is the usual

method of masturbation.

maternal mortalityThe death of a

woman during pregnancy, or within 42

days of childbirth, miscarriage, or an

inducedabortion, from any pregnancy-

related cause. Maternal mortality rate

describes the number of such deaths

per year per set number of pregnancies.

MASTICATION MATERNAL MORTALITY

M

MASTECTOMY

Lymph

node

SITE OF INCISION

Area of tissue

to be removed

Incision around
breast and into
armpit

Cancerous

tumour