Dermatome (anatomy)

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The dermatome (from ancient Greek δέρμα dérma ' skin ' and ancient Greek τομή tomḗ '(cut)') is the segmental area of ​​skin that is sensitively innervated by a spinal cord nerve ( spinal nerve ) .

Embryological basics

During the segmentation of the embryo in the trunk area from the paraxial mesoderm , to the side of the neural tube and the chorda dorsalis , initially the primary vertebra ( thus ) arise . The dermis is formed from its dorsolateral part . This plant is also known as a dermatome . As a result of this segmental origin of the individual skin areas, there is also a segmental assignment to the corresponding spinal nerve.


Dermatome and autonomous area
Dermatome in red / blue / green hatching, 1-3 plexus nerves and their autonomous area
Presentation of the spinal dermatomes on the surface of the skin. Attention: only very approximate representation, which deviates considerably from the actual course of the dermatomes in humans.

This segmental assignment of the spinal cord nerves to the corresponding skin areas is also retained in adults. The cell bodies of these sensitive neurons lie outside the spinal cord in the spinal ganglion ( ganglion spinal ). However, there is an overlap of the skin areas of the individual spinal nerves. If a spinal nerve is damaged, there is therefore no complete loss of sensitivity in the relevant dermatome. The overlap should be less pronounced for the perception of pain and temperature stimuli than of touch stimuli. Due to the overlap, a noticeable loss of sensitivity often only occurs when two adjacent segments fail.

Autonomous area

In the area of ​​the neck and in the lumbar and cruciform area, the ventral rami of the spinal nerves form plexuses :

The fiber exchange in these braids creates s. G. Plexus nerves. In most cases, these lead to nerve cell processes in several segments. An area of ​​skin that is only sensitively innervated by a certain nerve is also called the autonomous area of this nerve. Damage to the nerve typically leads to a loss of sensitivity in its autonomous area.

Selected autonomous areas:

Transferred pain

Since viscerosensitive ( viscera "intestines", "inner organs") sensations are transmitted via the spinal nerves, but these cannot be assigned to a precise location due to lack of experience in the responsible region of the cerebral cortex , these pains from the cerebrum are (incorrectly) corresponding sensitive skin areas , usually assigned to that of the same spinal nerve, for example shoulder pain in epigastric peritonitis . In diseases of internal organs, hypersensitivity to external stimuli can arise in a certain area of ​​the skin, the so-called Head's zone . This phenomenon is examined in diagnostics as a head zone sample (also Kalchschmidt sample). There may also be transferred pain in the muscles ( myotome ) of the corresponding segment ( Mackenzie zone ). An example of this is referred pain in angina pectoris .

The Head's zone (also Head zone), named after the English neurologist Sir Henry Head (1861-1940) is defined as the area of skin in the indented due to the body structure (→ metamerism ) a current via the associated spinal cord segment cross-connection between the somatic and the autonomic nervous system . Certain internal organs are assigned to this area, see the following table. Head's zone, which is assigned to a specific organ, can extend over several dermatomes, but has a reflexively significant maximum point. Irritation of the associated internal organ can result in a mostly equilateral pain zone via a viscerocutaneous reflex (hyperalgesia zone). This phenomenon is called referred pain . The pain can u. U. to spread to neighboring segments or the entire body half (generalization). Some alternative medical methods are supposed to use a reversal of the reflex process to influence internal organs by influencing certain skin zones mechanically, thermally or pharmacologically. These methods, for which there is no scientific evidence, are called reflex therapies .

organs Dermatome Body side
heart C 3-4, Th 1-5 predominantly left, also right arm
Thoracic aorta C 3-4, Th 1-7 both sides
Pleura Th 2-12 the respective half of the body (ipsilateral)
Lungs C 3-4 ipsilateral
esophagus Th 1-8 both sides
stomach Th (5) 6-9 Left
Liver and biliary tract Th (5) 6-9 (10) right
pancreas Th 6-9 forward Left
Duodenum Th 6-10 right
Jejunum Th 8-11 Left
Ileum Th 9-11 both sides
Cecum , proximal colon Th 9-10, L 1 right
distal colon Th 9 - L 4 Left
rectum Th 9 - L 4 Left
Kidney and ureter Th 9 - L 1 (2) ipsilateral
Adnexa Th 12 - L 4 ipsilateral
peritoneum Th 5-12 both sides
spleen Th 6-10 Left

See also

Individual evidence

  1. R. Putz, R. Pabst (Ed.): Sobotta, Atlas of the Anatomy of Man. Volume 2, 20th edition. Urban & Schwarzenberg, Munich 1993, ISBN 3-541-17370-X , p. 346.
  2. E Ernst, P Posadzki, MS Lee: Reflexology: an update of a systematic review of randomized clinical trials . In: Maturitas . 68, No. 2, February 2011, pp. 116-120. doi : 10.1016 / j.maturitas.2010.10.011 .
  3. Norbert Boss (Ed.): Roche Lexicon Medicine. 2nd Edition. Hoffmann-La Roche AG and Urban & Schwarzenberg, Munich 1987, ISBN 3-541-13191-8 , p. 744.