Bma Illustrated Medical Dictionary

(T1–T12), lumbar (L1–L5), and sacral

(S1–S5) regions. The entire body surface

is an interlocking pattern of dermatomes,

which is similar from one person to an-

other. Abnormal sensation in a dermatome

signifies damage to a particular nerve

root, commonly due to a disc prolapse.

dermatome, surgicalA surgical in-

strument for cutting varying thicknesses

of skin for use in skin grafting.

dermatomyositisA rare autoimmune

disorderin which the muscles and skin

become inflamed. It causes a skin rash

first on the bridge of the nose and cheeks,

followed by a purple discoloration on the

eyelids and sometimes a red rash on

the knees, knuckles, and elbows. Muscles

become weak, stiff, and painful, particu-

larly those in the shoulders and pelvis.

Treatment is with corticosteroid drugs

and/or immunosuppressant drugsand

physiotherapy. In about 50 per cent of

cases, full recovery occurs after a few

years. The remainder have persistent

muscle weakness. In about 20 per cent,

it eventually affects the lungs and other

organs and may be fatal.

dermatophyte infectionsA group of

common fungal infections affecting the

skin, h air, and nails, also known as

tineaand, popularly, as ringworm.

dermisThe inner layer of the skin.

dermographismAbnormal sensitivity

of the skin to mechanical irritation, to

the extent that firm stroking leads to the

appearance of itchy weals. The condi-

tion is a form of urticaria. It is most

common in fair-skinned people with a

tendency to allergic conditions.

dermoid cystA noncancerous tumour

with a cell structure similar to that of

skin. It contains hairs, sweat glands, and

sebaceous glands. Dermoid cysts may

also contain fragments of cartilage, bone,

and even teeth. The cysts may occur in

various parts of the body. Ovarian der-

moid cysts account for 10 per cent of all

ovarian tumours. Only rarely do they

become cancerous. In the skin, dermoid

cysts most commonly occur on the

head or neck. Surgical removal is usual-

ly recommended. (See also teratoma).

dermoid tumourSee dermoid cyst.

desensitizationA technique, used in

behaviour therapy for treating phobias,

in contact with the skin. Common caus-

es are detergents, nickel, certain plants,

and cosmetics. It may be treated with

topical corticosteroids. A patch test (see

skin tests) may be done to identify the

cause. Photodermatitis occurs in peo-

ple whose skin is abnormally sensitive

to light. A cluster of spots or blisters

occurs on any part of the body exposed

to the sun (see photosensitivity).

dermatitis artefactaAny self-induced

skin condition. It may range from a mild

scratch to extensive mutilation.

dermatitis herpetiformis A chronic skin

disease in which clusters of tiny, red,

intensely itchy blisters occur in a sym-

metrical pattern, most commonly on the

back, elbows, knees, buttocks, and scalp.

It usually develops in adult life and is

believed to be related to coeliac disease.

dermatologyThe branch of medicine

concerned with the skinand its disorders.

dermatomeAn area of skin supplied

with nerves by a pair of spinal nerve

roots from the cervical (C2–C8), thoracic

DERMATITIS ARTEFACTA DESENSITIZATION

D

Sacral region
(nerve S3)

Sacral region
(nerve S4)

Sacral
region
(nerve S5)

Sacral region
(nerve S1)

Sacral region
(nerve S2)

Cervical region
(nerve C5)

Cervical region

(nerve C2)

Cervical

region

(nerve C7)

Cervical region

(nerve C8)

Cervical region

(nerve C3)

Cervical region

(nerve C4)

Thoracic region

(nerves T1-T12)

Cervical region
(nerve C6)

Lumbar region
(nerves L1-L5)

Lumbar region
(nerve L1)

Lumbar region

(nerve L2)

Lumbar region
(nerve L3)
Lumbar region
(nerve L4)

Lumbar region

(nerve L5)

DERMATOME