3D Models Related Images

Anterior View of the Brainstem and Cerebellum with Longitudinal Fiber Tracts Exposed

Surgical Correlation


Anterior view of the brainstem and cerebellum with longitudinal fiber tracts exposed. The cerebral peduncle is a midbrain structure that contains motor fibers of the corticospinal, corticobulbar, and corticopontine tracts.  The oculomotor nerve (CN III) emerges from the interpeduncular fossa between the two cerebral peduncles. Fibers of the corticopontine tract synapse on pontine nuclei; fibers of the corticobulbar tract synapse on lower motor neurons of cranial nerve nuclei in the medulla; and fibers of the corticospinal tract continue through the pons and into the medulla where they form the medullary pyramids medial to the olivary eminence. The medial lemniscus is a bundle of sensory fibers that originate from neurons in the contralateral nucleus gracilis and nucleus cuneatus and ascends through the brainstem to the thalamus. Portions of the anterior lobe of the cerebellum have been removed along with most of the  middle cerebellar peduncles. The cerebellar tonsil is an ovoid structure located on the inferomedial aspect of the cerebellum adjacent to the medulla. The flocculus is a small lobe located along the posterior border of the medial cerebellar peduncle and anterior to the biventer lobe of the cerebellum. (Image courtesy of AL Rhoton, Jr.)