What is indicated by the prefix "encephalo-"?

The prefix "encephalo-" specifically refers to the brain. It is derived from the Greek word "encephalon," which means brain. This prefix is commonly used in medical terminology to form words associated with brain structures and conditions. For example, terms like "encephalitis" (inflammation of the brain) and "encephalopathy" (a disease of the brain) use this prefix to indicate their relation to the brain itself.

In contrast, other options indicate different anatomical structures or conditions, such as the spinal cord (not covered by "encephalo-"), the broader nervous system (which encompasses more than just the brain), and head trauma, which pertains to injuries rather than a specific anatomical reference. Thus, "encephalo-" accurately identifies concepts specifically linked to the brain, making it the correct choice.