Which organ contains arbor vitae?

• A. Cerebellum
• B. Cerebrum
• C. Brainstem
• D. Diencephalon

Answer: (A)

The concept being tested is the distinctive white-matter pattern found inside a specific brain structure. Arbor vitae refers to the branching, tree-like arrangement of white matter fibers within the cerebellum. This treelike core connects the cerebellar cortex (the outer gray matter) with the deep cerebellar nuclei and with brainstem pathways, enabling the cerebellum to coordinate movement and balance with fast, precise signaling. While other brain regions have white matter tracts, the term arbor vitae is specific to the cerebellum, so the cerebrum, brainstem, and diencephalon do not display this characteristic pattern. Therefore, the organ containing arbor vitae is the cerebellum.