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NEUROPHYSIOLOCY

Sensory Pathways: III

Schematic demarcation of dermatomes shown as distinct segments. Thcre is actually conśiderable overlap between any two adjacenl dermatomes

T10	Level of umbilicus
TI2	Inguinal or groin region*
LI, 2, 3,4	Anterior and inner surfaces of lowei limbs
L4, 3, SI	Coot
L4	Medial side of greal toe
SI, 2,13	Posterior and outer surfaces of lower limbs
SI	Lateral margin of foot and little toe
$2, 3, 4	Pciinetim

Lcvcls of principal dermatomes

C3    Clavides

CS, 6, 7    Latoral partS oł upper    liml is

C8, Tl    Mediał sides of uppoi    limbs

C6    Tliurnb

C6,7,8    Hand

C8    Ring and little fingers

T4    Level of nipples

Figurę 2.31 Dermatomes

Sensory intormation bel<nv the head is localized to specific areas of the body, which refled the distribution of peripheral sensory fibers that convey sensations to the spinał cord through the dorsal roots (sensory ner\'e celi bodies residc in the corres|>onding dorsal root ganglion}. The aiea of skin subserved by afferent fibers of one dorsal

root is called a dennatonte. This figurę shows the dermatome segment* and lists key dermatome levels used by clinicians. Variability and overlap occur. su all dermatome segments are only approxima-

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