Dermatomes

Original Editor - Lucinda hampton Top Contributors - Naomi O'Reilly, Anas Mohamed, Lucinda hampton, Joao Costa, Nikhil Benhur Abburi, Rachael Lowe, Kim Jackson and Blessed Denzel Vhudzijena




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Dermatomes

A dermatome is an area of skin that is mainly supplied by a single spinal nerve. There are 8 cervical nerves (note C1 has with no dermatome), 12 thoracic nerves, 5 lumbar nerves and 5 sacral nerves. Each of these spinal nerves relay sensation from a particular region of the skin to the brain.

The nerves from the upper cervical spine supply the skin of the neck. C5 to T1 nerves supply the arms. T2 to L2 nerves supply the chest and abdomen.  L3 to S1 nerves supply the skin of the legs.  S1-C1 nerves go to the groin.

Nerve Roots Dermatomes

Nerve Root	Dermatomes
Cervical
C2	Temple, forehead, occiput
C3	Entire neck, posterior cheek, temporal area, prolongation forward under mandible
C4	Shoulder area, clavicular area, upper scapular area
C5	Deltoid area, anterior aspect of entire arm to base of thumb
C6	Anterior arm, radial side of hand to thumb and index finger
C7	Lateral arm and forearm to index, long, and ring fingers
C8	Medial arm and forearm to long, ring, and little fingers
Thoracic
T1	Medial side of forearm to base of little finger
T2	Medial side of upper arm to medial elbow, pectoral and midscapular areas
T3-T12	T3–T6, upper thorax; T5–T7, costal margin; T8–T12, abdomen and lumbar region
Lumbar
L1	Back, over trochanter and groin
L2	Back, front of thigh to knee
L3	Back, upper buttock, anterior thigh and knee, medial lower leg
L4	Medial buttock, latera thigh, medial leg, dorsum of foot, big toe
L5	Buttock, posterior and lateral thigh, lateral aspect of leg, dorsum of foot, medial half of sole, first, second, and third toes
Sacral
S1	Buttock, thigh, and leg posterior
S2	Same as S1
S3	Groin, medial thigh to knee
S4	Perineum, genitals, lower sacrum

Purpose

Testing of dermatomes is part of the neurological examination looking for radiculopathy as sensation changes within a specific dermatome may help in determining the pathological disc level.

Technique

Dermatome Testing is done ideally with a pin and cotton wool. Ask the patient to close their eyes and give the therapist feedback regarding the various stimuli. Testing should be done on specific dermatomes and should be compared to bilaterally.

Pinprick test (pain sensation) - Gently touches the skin with the pin ask the patient whether it feels sharp or blunt

Light touch test (light touch sensation) -Dab a piece of cotton wool on an area of skin