The arbor vitae is a tree-shaped white-colored component found in the cerebellum. It is known for its role in motor and sensory information that goes to and from this region of the brain, which is the center of the body’s nervous system. Due to its shape and structure, as well as its functions, its name means “tree of life” in Latin.
The cerebellum is the part of the brain that regulates a person’s motor control. This involves how the body moves and the sequence of body movements. More specifically, it plays a part in a person’s timing, coordination, and precision of movement. It does this by connecting with the body’s system of sensory organs, as well as inputs from other parts of the nervous system.
One of the inputs that it relies on is the arbor vitae, which is situated in the middle of the cerebellum. It belongs to a class of one of two main components of the central nervous system (CNS) known as white matter; the other main component is grey matter. The structure is mostly composed of myelinated axons, nerve fibers that are responsible for transmitting signals through the brain and spinal cord. It gets its pinkish-white color from the fatty component, myelin, which covers the axons.
White matter works with the grey matter in the brain. Acting as a network cable, it transports signals from grey matter to parts of the body’s nervous system, including the cerebellum. The myelin that surrounds the axons comprising the arbor vitae insulates its branches, speeding up the transmission of information.
This structure in particular, due to its branches, surrounds or can be found next to four types of grey matter in the cerebellum. There is the dentate nucleus, which comprises the biggest single structure that links the cerebellum with the other parts of the brain. Lying to the dentate nucleus’ medial side is the emboliform nucleus, which joins the globose nucleus to form the interposed nucleus. The globose nucleus is located lateral to the fastigial nucleus. These grey-matter aggregates form the four pairs of nuclei found in the cerebellum.
The “tree of life” moniker is a reference to an actual genus of coniferous trees in the cypress family. Called Thuja, trees in this genus are native to North America and Western Asia. The name also serves as a metaphor for the arbor vitae's interconnection within the cerebellum.