Flocculonodular lobe
The flocculonodular lobe is one of the lobes of the cerebellum. It is a small lobe consisting of the unpaired midline nodule and the two flocculi: one flocculus on either side of the nodule. The lobe is involved in maintaining posture and balance as well as coordinating head-eye movements.
The lobe is functionally associated with the vestibular system and is therefore also referred to as the vestibulocerebellum. It receives second-order fiber afferents from the vestibular nuclei as well as direct first-order afferents from the vestibular ganglion/nerve.
The lobe in turn projects efferents back to the vestibular nuclei which in turn give rise or project to: the lateral vestibulospinal tracts which maintain posture and balance by regulating tone of the axial and proximal limb extensor mucles ; the medial vestibulospinal tracts which regulate the tone of neck muscles; and the medial longitudinal fasciculi which coordinates head-eye movements.
Anatomy
Afferents
Afferents of the lobe are the vestibulocerebellar fibers arising from either the vestibular nuclei or the vestibular nerve/ganglion directly.- Vestibular organs → vestibular nerve/vestibular ganglion first-order fibers → juxtarestiform body of inferior cerebellar peduncle → flocculonodular lobe of cerebellum
Efferents
Efferents of the lobe are the cerebellovestibular fibers which project to the vestibular nuclei.- Purkinje cells of flocculonodular lobe → juxtarestiform body of inferior cerebellar peduncle → vestibular nuclei →
- * Medial and lateral vestibulospinal tracts → lower motor neurons → skeletal muscle
- * Medial longitudinal fasciculi → nuclei of cranial nerves III/IV/VI → cranial nerves III/IV/VI → extrinsic eye muscles
Clinical significance
Lesions to this area can result in multiple deficits in visual tracking and oculomotor control, integration of vestibular information for eye and head control, as well as control of axial muscles for balance.The most common cause of damage to the flocculonodular lobe is medulloblastoma in childhood.