MODULE 6 - SECTION 6 - OUTPUTS PATHWAYS from the CEREBELLUM Note that the lateral part of the hemisphere (the cerebrocerebellum) projects to the dentate nucleus - easily seen on Cu Slide 04. The intermediate part of the hemisphere (one component of the spinocerebellum) projects to the globose and emboliform nuclei. These nuclei, together, are also called the interposed nuclei. After relay in these deep nuclei, fibers of both pathways depart from the cerebellum in the superior cerebellar peduncle and continue into its rostral extension, across the midline as the dentato-rubro-thalamic pathway. Finally trace this path as it passes forward to its decussation and the red nucleus. |
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ZONES of the CEREBELLAR HEMISPHERE The cerebellum is divided into lateral, intermediate and vermal zones. Each projects to its own set of deep nuclei, and the function carried out by each zone is distinct from that of the others. This view shows these divisions,drawn on a surface view of the cerebellum. |
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Cu Slide 04 cu04_cbm_3.jpj A quick look at this slide tells us something about the internal anatomy of the cerebellum. The cerebellum is divided into lateral, intermediate and vermal zones. Each projects to its own set of deep nuclei, and the function carried out by each zone is distinct from that of the others. |
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THE "RETURN" PATHWAY from the LATERAL HEMISPHERE |
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THE SUPERIOR CEREBELLAR PEDUNCLE ASCENDS to the MIDBRAIN The superior cerebellar peduncle, carrying fibers from the dentate, globose and emboliform nuclei, has now left the cerebellum and is passing ventrally through the tegmentum of the brainstem. Ignore the blue lines, showing the formation of the middle cerebellar peduncle.
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THE SUPERIOR CEREBELLAR PEDUNCLE ASCENDS to the MIDBRAIN The superior cerebellar peduncle, carrying fibers from the dentate, globose and emboliform nuclei, is passing ventrally through the tegmentum of the brainstem. Ignore the blue lines, showing the formation of the middle cerebellar peduncle.
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DECUSSATION of the SUPERIOR CEREBELLAR PEDUNCLE The superior cerebellar peduncle, carrying fibers from the dentate, globose and emboliform nuclei, now decussates Ignore the fibers of the descending pathways, shown within the cerebral peduncle.
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THE SUPERIOR CEREBELLAR PEDUNCLE enters the RED NUCLEUS The superior cerebellar peduncle, carrying fibers from the dentate, globose and emboliform nuclei, now approaches the red nucleus. Ignore the fibers of the descending pathways, shown within the cerebral peduncle.
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THE SUPERIOR CEREBELLAR PEDUNCLE enters the RED NUCLEUS At the level of the red nucleus, the output limbs of the pathways part company. Fibers of the cortical path(the one originating in the dentate nucleus) may relay in the parvocellular part of the red nucleus but for the most part continue on to terminate in the nucleus ventralis lateralis of the thalamus (see Slides 28 & 30). From there they project to the premotor area of the cortex (Area 6). Fibers of the spinal cord path (the ones originating in the globose and emboliform nuclei) terminate in the magnocellular part of the red nucleus ending upon cells that contribute axons to the rubrospinal pathway. Thus, the rubrospinal path completes the spinal cord loop and is the route by which the intermediate part of the cerebellum can modify ongoing motor activity. |
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CEREBELLOTHALAMIC FIBERS approach the THALAMUS Fibers of the cortical pathway continue rostrally. Here they are labeled cerebellothalamic fibers. They are moving laterally, just ventral to VPM and VPL, to approach the nucleus ventralis lateralis. |
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CEREBELLOTHALAMIC FIBERS enter VENTRALIS LATERALIS Fibers of the cortical pathway now enter the nucleus ventralis lateralis. After a synaptic relay here, the pathway continues onward to the cortex, passing through the internal capsule. |
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