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
C1	Vertex of skull
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
T1
T2
T3-T12
L1
L2
L3
L4
L5
S1
S2
S3
S4

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