Corrected version: "In a filled-in outline of the human body, draw the brain connected through the brainstem to the spinal cord and the nerves that run throughout the entire body."
Explanation:
- "filled in" should be hyphenated to "filled-in" as it acts as a compound adjective describing "outline."
- A comma is added after "human body" to separate the introductory phrase from the main clause.
- Rephrased "draw the brain that connects" to "draw the brain connected" to sound clearer and more natural.
- Added "the" before "nerves."
- Replaced "across the whole body" with "throughout the entire body" for more precise expression.