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Dermatomes and Myotomes. Dr Edrish Contractor. Introduction . Spinal nerves have motor fibres and sensory fibres . The motor fibres innervate certain muscles, while the sensory fibres innervate certain areas of skin.
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Dermatomes and Myotomes Dr Edrish Contractor
Introduction • Spinal nerves have motor fibres and sensory fibres. • The motor fibres innervate certain muscles, while the sensory fibres innervate certain areas of skin. • A skin area innervated by the sensory fibres of a single nerve root is known as a dermatome • A group of muscles primarily innervated by the motor fibres of a single nerve root is known as a myotome. • Although slight variations do exist, dermatome and myotome patterns of distribution are relatively consistent from person to person.
Clinical significance • Dermatomes are useful to help localize neurologic levels, particularly in radiculopathy. • American Spinal Injury Association classification • Dermatomes are clinically important and necessary for assessing and diagnosing the level of spinal cord injury in the American Spinal Injury Association (ASIA) Impairment scale.[2]
Example • Pain radiating down the back of leg to the small toes in the general pattern of the S1 dermatome suggests that a herniated disk may be pinching the S1 nerve root in the spine.
