A dermatome is an area of skin that is mainly supplied by a single spinal nerve root. Each dermatome corresponds to a specific segment of the spinal cord, allowing healthcare professionals to assess nerve function and diagnose conditions related to nerve damage or injury. Dermatomes are important in understanding conditions like shingles, which can cause pain and rashes in specific dermatomes. They are also used in procedures like spinal anesthesia and nerve blocks to target specific areas of the body for pain relief or surgical interventions.