Lecture 9 Cerebellum Flashcards
What functions is our cerebellum involved in?
- coordination
- balance and equilibrium
- muscle tone
- motor control
- motor learning
Where is the cerebellum located?
- posterior fossa
- infratentorial
- dorsal to midbrain and 4th ventricle
How is the cerebellum similar in structure to the cerebrum?
- has 2 hemispheres that are split down the middle
- Latin for little brain
What is the target structure for the superior cerebellar peduncle and what type of fibers does it carry?
- cerebellum to midbrain
- afferent and efferent fibers
What is the target structure for the middle cerebellar peduncle and what type of fibers does it carry?
- cerebellum to pons
- afferent fibers
What is the target structure for the inferior cerebellar peduncle and what type of fibers does it carry?
- cerebellum to medulla
- afferent and efferent fibers
What is the only way in and out of the cerebellum?
through the cerebellar peduncles
What cerebellar peduncles connect ipsilaterally?
middle and inferior cerebellar peduncle
Which peduncle decussates?
superior cerebellar peduncle
What structures/regions are involved with cerebrocerebellum? What are the function?
- input to/from the cortex
- involved with planning and initiation of movement
What structures/regions are involved with spinocerebellum? What are the function?
- Input to/from spinal cord
- vermis - posture, proximal limb movement, eye movement
- intermediate zone - integrates input re: appendicular limb positions and somatosensory
What structures/regions are involved with vestibulocerebellum? What are the function?
- input to/from vestibular labyrinth
- maintenance of equilibrium, balance, and posture
What are the two types of fibers involved in synaptic input to the cerebellum? Where do they project from and where do they synapse?
Climbing fibers
- Excitatory fibers from contralateral inferior olivary nucleus (medulla) that synapse w/: deep cerebellar nuclei and Purkinje cells
Mossy fibers
- Excitatory fibers from all areas of afferent input except inferior olivary nucleus that synapse with:
Deep cerebellar nuclei, Granule Cells, Parallel Cells, Purkinje Cells, Golgi cells
What are the 3 layers found in the cerebellar gray matter?
- Molecular layer
- Purkinje cell layer
- Granule cell layer
What can be found in the molecular layer?
- interneurons
- unmyelinated granule cell axons
- Purkinje dendrites
- Parallel fibers
What can be found in the Purkinje Cell Layer?
Purkinje cell bodies
What can be found in the Granule cell layer?
- granule cells
- golgi cells
What are the basic functions of Parallel fibers?
- telephone wires
- form excitatory synapses with cells
What are the basic functions of Purkinje fibers?
- output fibers of cerebellum
- inhibit deep cerebellar nuclei and vestibular nuclei to modulate activity of their output onto descending cortical system
What are the basic functions of Granule Cells?
- excitatory cells that bifurcate with parallel fibers to turn them on
What are the basic functions of Golgi cells?
- inhibitory neurons that inhibit granule cells
- needed when we get the movement right the first time
Describe the basic pathway taken by pontocerebellar fibers. Where do these fibers receive input from?
- receive input from primary somatosensory cortex, primary motor cortex, visual cortex, vestibular and auditory
- cortex through internal capsule to ipsilateral Pontine nuclei then mossy fibers decussate prior to entering contralateral middle cerebellar peduncle then project to cerebellar cortex
Describe the basic pathway taken by olivocerebellar fibers. Where do these fibers receive input
- receives input from red nucleus, cortex, brainstem, spinal cord
- then sends info down central tegmental tract to inferior olivary nucleus, then climbing fibers decussate prior to entering contralateral inferior cerebellar cortex then on to cerebellar cortex
Describe the somatotopic organization seen within the cerebellum
- towards the middle and medial is head and as you go inferior it goes arms then legs
What are the 4 sets of deep cerebellar nuclei?
- dentate
- emboliform
- globose
- fastigial
What structures does the posterior inferior cerebellar artery supply?
- lateral medulla
- inferior half of cerebellum
- inferior vermis
What structures does the anterior inferior cerebellar artery supply?
- inferior lateral pons
- middle cerebellar peduncle
- middle of cerebellum
- flocculus
What structures does the superior cerebellar artery supply?
- upper lateral pons
- superior cerebellar peduncle
- most of superior half of cerebellar hemisphere
- deep cerebellar nuclei
- superior vermis
