1. a specialist in the anatomy, functions, and organic disorders of nerves and the nervous system.
How I know by the context clues for nerves which is the nervous system and the definition is included with nerves.
2. a poison which acts on the nervous system.
How I know is because in the sentence the clue words are paralyzed or something.
3. relating to nerves and muscles.
Clue words are difficulty I think?
4. A neurosurgeon is a physician who specializes in the diagnosis and surgical treatment of disorders of the central and peripheral nervous system including congenital anomalies, trauma, tumors, vascular disorders, infections of the brain or spine, stroke, or degenerative diseases of the spine
Clue words are tumor and brain.
Hope this helps!