Dermatomes: Difference between revisions
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== Dermatomes == | == Dermatomes == | ||
A dermatome is an area of [[skin]] that is mainly supplied by the afferent nerve fibres from the dorsal root of a single [[Spinal Nerves|spinal nerve]]. In total there are 30 | A dermatome is an area of [[skin]] that is mainly supplied by the afferent nerve fibres from the dorsal root of a single [[Spinal Nerves|spinal nerve]]. In total there are 30 spinal nerve roots who relay sensation from a particular region of the skin to the [[Brain Anatomy|brain]] - 8 [[Cervical Anatomy|cervical]] nerves (note [[Atlas|C1]] has no corresponding dermatomal area), 12 [[Thoracic Anatomy|thoracic]] nerves, 5 [[lumbar]] nerves and 5 [[Sacrum|sacral]] nerves. Each of these spinal nerves roots.<ref>Wikipedia [https://en.wikipedia.org/wiki/Dermatome_(anatomy) Dermatome]. Available from: https://en.wikipedia.org/wiki/Dermatome_(anatomy) (last accessed 23.4.2019)</ref> Dysfunction or damage to a spinal nerve root from infection, compression, or traumatic injury can trigger symptoms in the corresponding dermatome. <ref name=":1">Medical news today What and where are dermatomes? Available:https://www.medicalnewstoday.com/articles/what-are-dermatomes (accessed 25.5.2022)</ref> {{#ev:youtube|https://www.youtube.com/watch?v=CYZBH6NX8wg&feature=youtu.be|width}}<ref>M Roehrs. Dermatomes. Available from: https://www.youtube.com/watch?v=CYZBH6NX8wg&feature=youtu.be (last accessed 23.4.2019)</ref> | ||
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|+'''Table.1''' Dermatomes | |+'''Table.1''' Dermatomes | ||
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Dermatomes[edit | edit source]
A dermatome is an area of skin that is mainly supplied by the afferent nerve fibres from the dorsal root of a single spinal nerve. In total there are 30 spinal nerve roots who relay sensation from a particular region of the skin to the brain - 8 cervical nerves (note C1 has no corresponding dermatomal area), 12 thoracic nerves, 5 lumbar nerves and 5 sacral nerves. Each of these spinal nerves roots.[1] Dysfunction or damage to a spinal nerve root from infection, compression, or traumatic injury can trigger symptoms in the corresponding dermatome. [2]
| Nerve Root | Dermatome | ||
|---|---|---|---|
| Cervical | C2 | Supply Skin of Neck | Temple, Forehead, Occiput |
| C3 | Entire Neck, Posterior Cheek, Temporal Area, Prolongation forward under Mandible | ||
| C4 | Shoulder Area, Clavicular Area, Upper Scapular Area | ||
| C5 | Supply the Arms | 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 | Supply the chest and abdomen | Medial side of upper arm to medial elbow, pectoral and midscapular areas | |
| T3 - 6 | Upper Thorax | ||
| T5 - 7 | Costal Margin | ||
| T8 - 12 | Abdomen and Lumbar Region | ||
| Lumbar | L1 | Back, over trochanter and groin | |
| L2 | Back, front of thigh to knee | ||
| L3 | Supply Skin of Legs | 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 | Supply Groin | Same as S1 | |
| S3 | Groin, medial thigh to knee | ||
| S4 | Perineum, genitals, lower sacrum | ||
| Coccygeal | The dermatome corresponding with the coccygeal nerves is located on the buttocks, in the area directly around the coccyx.[4][5] | ||
Purpose[edit | edit source]
Testing of dermatomes is part of the neurological examination. They are primarily used to determine whether the sensory loss on a limb corresponds to a single spinal segment, implying the lesion is of that nerve root (i.e., radiculopathy), and to assign the neurologic “level” to a spinal cord lesion[6].
Technique[edit | edit source]
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.
- Light Touch Test - Light Touch Sensation - Dab a piece of cotton wool on an area of skin [7]
- Pinprick Test - Pain Sensation - Gently touches the skin with the pin ask the patient whether it feels sharp or blunt
During the review of systems, asking the patient to carefully describe the pattern or distribution of sensory symptoms (e.g., tingling, numbness, diminished, or absent sensation) provides the therapist with preliminary information to help guide the examination and to assist in identifying the dermatome(s) and nerve(s) involved.[8]
Light touch dermatomes are larger than pain dermatomes. When only one or two segments are affected, testing for pain sensibility is a more sensitive method of examination than testing for light touch.[6]
Controversies[edit | edit source]
Dermatomes have a segmented distribution throughout your body. The exact dermatome pattern can actually vary from person to person. Some overlap between neighboring dermatomes may also occur. There exist some discrepancies among published dermatome maps based on the methodologies used to identify skin segment innervation. In a clinical commentary, Downs and Laporte discuss the history of dermatome mapping, including the variations in methodologies employed, and the inconsistencies in the dermatome maps used in education and practice.[8] [[Laporte C. Conflicting dermatome maps: educational and clinical implications. journal of orthopaedic & sports physical therapy. 2011 Jun;41(6):42[9]7-34.]]
Clinical Significance[edit | edit source]
Dermatomes are important because they can help to assess and diagnose a variety of conditions. Neurological evaluation of dermatomes helps to assess patterns of sensory loss that can suggest specific spinal nerve involvement. For instance, symptoms that occur along a specific dermatome may indicate disruption or damage to a specific nerve root in the spine.
References[edit | edit source]
- ↑ Wikipedia Dermatome. Available from: https://en.wikipedia.org/wiki/Dermatome_(anatomy) (last accessed 23.4.2019)
- ↑ 2.0 2.1 Medical news today What and where are dermatomes? Available:https://www.medicalnewstoday.com/articles/what-are-dermatomes (accessed 25.5.2022)
- ↑ M Roehrs. Dermatomes. Available from: https://www.youtube.com/watch?v=CYZBH6NX8wg&feature=youtu.be (last accessed 23.4.2019)
- ↑ Medical news today What and where are dermatomes? Available:https://www.medicalnewstoday.com/articles/what-are-dermatomes (accessed 25.5.2022)
- ↑ David J. Magee. Orthopedic Physical Assessment. 6th edition. Elsevier. 2014.
- ↑ 6.0 6.1 Liebenson C, editor. Rehabilitation of the spine: a practitioner's manual. Lippincott Williams & Wilkins; 2007.Available: https://www.sciencedirect.com/topics/medicine-and-dentistry/dermatome (accessed 25.5.2022)
- ↑ Slide share. Dermatomes and myotomes. Available from: https://www.slideshare.net/TafzzSailo/special-test-for-dermatomes-and-myotomes (last accessed 23.4.2019)
- ↑ 8.0 8.1 Susan B.O'Sullivan, Thomas J. Schmitz, George D. Fulk. Physical Rehabilitation. 6th edition. F. A. Davis Company. 2014.
- ↑ Downs MB, Laporte C. Conflicting dermatome maps: educational and clinical implications. journal of orthopaedic & sports physical therapy. 2011 Jun;41(6):427-34.
