Inferior olivary nucleus

The inferior olivary nucleus is the largest nucleus situated in the olivary body, part of the medulla oblongata.

Function
It is closely associated with the cerebellum, meaning that it is involved in control and coordination of movements, sensory processing and cognitive tasks likely by encoding the timing of sensory input independently of attention or awareness. There is some evidence that it is stimulated by ghrelin.

Anatomy
It consists of a gray folded lamina arranged in the form of an incomplete capsule, opening medially by an aperture called the hilum.

Olivocerebellar fibers are neurons that have their cell bodies in the inferior olivary nucleus. Their axons leave medially through the hilum, cross the midline, and ascend into the cerebellum via the inferior cerebellar peduncle. Once they enter the cerebellum, they are referred to as the climbing fibers. Finally, they terminate by synapsing in the cerebellar cortex, including the cortex of the vermis, paramedian lobule, and the cerebellar hemispheres.

The fibers leaving the inferior olivary nucleus at the hilum may be referred to as the "peduncle" of the olive. They cross with those from the opposite olive in the raphe. After the raphe, they may be referred to as the internal arcuate fibers.

The fibers are smaller than the internal arcuate fibers connected with the medial lemniscus.

Fibers passing in the opposite direction from the cerebellum to the olivary nucleus are often described as the CTT, but their existence is doubtful.

Much uncertainty exists also with regard to the connections of the olive and the spinal cord.

Important connections between the cerebrum and the olive of the same side exist, but the exact pathway is unknown.

Many collaterals from the reticular formation and from the pyramids enter the inferior olivary nucleus.

Removal of one cerebellar hemisphere is followed by atrophy of the opposite olivary nucleus.

Pathology
Hypertrophy has been associated with progressive supranuclear palsy.