Thalam- refers to which of the following?

• A. Outer Layer
• B. Middle
• C. Cavity
• D. Inner Chamber

Answer: (D)

Thalam- comes from a Greek word meaning inner chamber. In anatomy, this root is used for structures related to an inner, central space. The brain’s thalamus is a deep, central relay station that sits near the brain’s ventricular system—an inner chamber of the brain—so the term conveys that sense of an inner chamber. That’s why inner chamber is the best match.

The other descriptions don’t fit because they point to different kinds of regions: outer layer would be like the skin’s surface layers, middle refers to a mid-region, and cavity is a hollow space, which aren’t what thalam- denotes.