When Harvey Williams Cushing was autopsied in 1939, pathologists found a tumor hidden in the third ventricle of his own brain, the hardest place in the skull to reach. It was a stunning irony for the man who dragged brain surgery out of the dark ages and turned it into a precise, measurable discipline.

This episode traces Cushing's path from a Cleveland medical dynasty through mentorships that fused surgical precision with brain mapping. It covers his discovery of the Cushing reflex, his role in bringing the blood pressure cuff to America, his battlefield innovations in World War I, his work on the pituitary gland, and his Pulitzer Prize-winning biography of Sir William Osler.

• Recognizing rising intracranial pressure through the Cushing reflex
• Mandating blood pressure measurement as a standard vital sign
• Inventing ...