Arcuate nucleus of medulla oblongata

The arcuate nuclei of medulla oblongata are small clusters of neuronal cell bodies located on the anterior (ventral) surface of the medullary pyramids. These nuclei are considered homologous to the pontine nuclei found in the ventral pons and serve a crucial role in the feedback loop between the cerebrum and cerebellum.

Efferent fibers originating from the arcuate nuclei form the anterior external arcuate fibers, which cross the external surface of the medulla and connect with the cerebellum via the inferior cerebellar peduncle. Although the anterior external arcuate fibers are integral to the neuronal loop connecting the cerebral cortex with the cerebellum, they are separate from the pontocerebellar fibers. The anterior external arcuate fibers emerge from the medullary arcuate nuclei and utilize the inferior cerebellar peduncle, whereas the pontocerebellar fibers are part of the corticopontocerebellar pathway, originating from the pontine nuclei in the pons and reaching the cerebellum via the middle cerebellar peduncle.