A 45-year-old man develops a lesion at the level of the inferior olivary nucleus following a posterior inferior cerebellar artery (PICA) infarct. The inferior olivary nucleus forms a key relay in which cerebellar circuit?

• A Spinocerebellar tract projecting to ipsilateral cerebellar cortex via mossy fibers
• B Dentato-rubro-thalamic tract carrying cerebellar output to premotor cortex
• C Reticulocerebellar tract carrying pontine reticular formation signals
• D Olivocerebellar tract projecting to contralateral cerebellar cortex via climbing fibers ✓

Explanation

The inferior olivary nucleus projects via the olivocerebellar tract, crossing to the contralateral cerebellum as climbing fibers that synapse directly on Purkinje cell dendrites. Climbing fibers are the most powerful excitatory input to cerebellar cortex and mediate error signals for motor learning. Mossy fibers originate from the pontine nuclei and spinocerebellar tracts, not the inferior olivary nucleus. The dentato-rubro-thalamic tract is an output pathway, not an input relay.

Reference: BD Chaurasia's Human Anatomy, 8th ed.

High-yield for: NEET PGINI-CETNExTFMGEUSMLEPLABMRCP

Written and medically reviewed by the StethoPrep medical team.