Bma Illustrated Medical Dictionary

teeth can be anchored to firmer teeth

by splinting (see splinting, dental).

period painSee dysmenorrhoea.

periosteumThe tissue that coats all of

the bonesin the body except the joint

surfaces. The periosteum contains small

blood vessels and nerves, and produces

new bone in the initial stages of healing

following a fracture.

periostitisInflammation of the perios-

teum. The usual cause is a blow that

presses directly on to bone. Symptoms

include pain, tenderness, and swelling

over the affected area.

peripheral nervous systemAll the

nerves that fan out from the central ner-

vous system to the muscles, skin,

internal organs, and glands (see nerve;

cranial nerves; spinal nerves).

peripheral vascular diseaseNarrow-

ing of blood vessels in the legs, and

sometimes in the arms, restricting

blood flow and causing pain. In severe

cases, gangrene may develop. In most

affected people, peripheral vascular dis-

ease is caused by atherosclerosis. The

greatest risk factor is smoking. Diseases

of the peripheral vessels that are not

caused by atherosclerosis include Buer-

ger’s disease, Raynaud’s disease, deep

vein thrombosis, and varicose veins.

The first symptom of narrowed arter-

ies due to atherosclerosis is usually an

aching feeling in the leg muscles when

walking, which is relieved by resting.

Pain recurs after the same amount of

perimetryA visual field test to deter-
mine the extent of peripheral vision.
(See eye, examination of.)
perinatalRelating to the period just
before or just after birth. The perinatal
period is often defined as the period
from the 28th week of pregnancy to the
end of the 1st week after birth.
perinatologyA branch of obstetrics and
paediatricsconcerned with the study and
care of the mother and baby during preg-
nancy and just after birth.
perineumThe area bounded internally
by the pelvic floor (the muscles that sup-
port the pelvis) and the surrounding
bony structures. Externally, the perineum
is the area that lies behind the genitals
and in front of the anus.
periodic feverAn inherited condition
causing recurrent bouts of fever. (See
familial Mediterranean fever.)
period, menstrualSee menstruation.
periodontal diseaseAny disorder of
the periodontium (the tissues that sur-
round and support the teeth).
periodonticsThe branch of dentistry
concerned with periodontal disease.
periodontitisInflammation of the peri-
odontium (the tissues surrounding the
teeth). There are 2 types: periapical and
chronic. Periapical periodontitis results
from neglected dental caries and occurs
when bacteria enter the tooth pulp and
spread to the root tip, sometimes caus-
ing a dental abscess, granuloma, or cyst.
Chronic periodontitis is a result of un-
treated gingivitis, in which bacteria attack
the periodontal tissues. This type is the
major cause of adult tooth loss.
Periapical periodontitis may cause
toothache, especially on biting. An ab-
scess may make the tooth loose; a large
dental cyst may cause swelling of the
jaw. In chronic periodontitis, the signs
of gingivitis are present.
Periodontitis is diagnosed by a dental
examination and dental X-rays. Periapi-
cal periodontis is treated by draining pus
and filling the tooth or by extraction.
Regular teeth cleaning can prevent
advanced chronic periodontal disease
and further destruction of the tissues.
Treatment may include root planing,
scaling, gingivectomy, or curettage (see
curettage, dental). Sometimes, loose

PERIMETRY PERIPHERAL VASCULAR DISEASE

P

PERIOSTEUM

Periosteum

Blood

vessel

Spongy Nerve

bone

Compact

bone

STRUCTURE OF BONE