(slang) endorphin or adrenaline

intracerebral; intracranial; the inside of the head / (figuratively) the inside of one's mind; within one's mind; mental (of imagined things, etc.)

(Internet slang) person who inflames public anxiety and/or fear with groundless information about radioactivity.

(slang) meathead; dumb muscle; someone that often uses physical strength without thinking

(anatomy) trigeminal nerve

motor nerves / (figuratively) reflexes

being inconsiderate; being insensitive

inconsiderate; insensitive

neurology

(idiomatic) to be extremely or excessively vigilant