3D Models Related Images

Anterior Surface of Pons and Proximal Medulla with Associated Nerves

Surgical Correlation


Anterior surface of pons and proximal medulla with associated nerves. The trochlear nerve emerges from the dorsal surface of the midbrain and wraps around the cerebral peduncle before coursing forward toward the cavernous sinus. The trigeminal nerve emerges from the anterolateral surface of the pons adjacent to the middle cerebellar peduncle (MCP).  The MCP conveys fibers from contralateral pontine nuclei to the cerebellum (part of the corticopontocerebellar pathway) for coordinating and planning motor tasks. The facial and vestibulocochlear nerves emerge along the lateral aspect of the pontomedullary junction in proximity to the choroid plexus of the fourth ventricle. Anterior and medial at this junction arise the abducens nerves. The anterior median fissure separates the pyramids of the medulla, which contain corticospinal fibers that decussate in the caudal medulla to descend into the spinal cord. The pyramids are flanked laterally by the olives. The anterolateral or preolivary sulci intervene between the pyramids and the olives.  From these sulci emerge the roots of the hypoglossal nerve (not visible in this dissection). The roots of the glossopharyngeal, vagus, and accessory nerves emerge in a rostro-caudal sequence from the postolivary sulci. (Image courtesy of PA Rubino)