CEREBELLUM

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CEREBELLUM
Dr Hina Khalil Malik Department of Anatomy Fatima
Jinnah Dental College
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Anatomy
Seen from feet

• Located dorsal to pons and medulla
• In posterior fossa under tentorium cerebelli
• Lobes
• Floccular Nodular(small fluffy mass)
• Anterior
• Posterior

Anterior lobe (H)
Posterior lobe (I)
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Flattened Cerebellum

• Longitudinally separated into hemispheres and
  cortices
• Median (Vermis)

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Cerebellum
Paramedian
Primary Fissure
Median
Horizontal Fissure
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STRUCTURE

• Gray matter, cortex intercerebellar nuclei
• White matter

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Cellular layer
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FUNCTIONAL AREA

• Cortex
• Intermediate zone
• Lateral zone

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Cerebellar Nuclei

• Dentate nucleus
• Largest, communicates through cerebellar peduncle
  
• Carries information important for coordination of
  limb movements (along with the motor cortex and
  basal ganglia)
• Emboliform nucleus (medial side of the nucleus
  dentatus)
• Regulates movements of ipsilateral extremity
• Globose nucleus
• Regulates movements of ipsilateral extremity
• Fastigial nucleus
• Regulates body posture
• Is related to the flocculo nodular lobe

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WHITE MATTER

• 3 groups of fibers
• Intrinsic
• Afferent-middle inf cereb peduncle
• Efferent

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• Climbing fibers
• Mossy fibers
• FUNCTIONAL UNIT OF THE CEREBELLAR CORTEX

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Dentate Nucleus
Dentate Nucleus
Pontine Projections
Superior Cerebellar Peduncle
Pons
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Cerebellar peduncle

• Superior-midbrain
• Middle-pons
• Inferior-medulla

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CEREBELLAR NERVE FIBERS

• Afferent fibers
• i. from the cerebral cortex
• ii. from the spinal cord
• iii. others ( red nucleus tectum)
• Efferent fibers

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i.Cerebellar afferent fibers from the cerebral
cortex

• 3 pathways
• Corticopontocerebellar
• Cerebro-olivocerebellar
• Cerebroreticulocerebellar

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1.Corticopontocerebellar pathway

• Info From Pontine Nuclei (via middle cereb
  peduncle) From Opposite Cerebral Cortex, Visual
  and Auditory Inputs
• To Opposite Cerebellar Hemisphere
• Conveys control

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2.Cerebro-olivocerebellar pathway

• Info From Spinal Cord Through Olivary N to
  Contralateral Cerebellar Hemisphere via inf cereb
  peduncle
• Source of Climbing Fibers for Direct Input to
  Cerebellum
• Conveys control

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3.Cerebroreticulocerebellar pathway

• Info From Cerebral Cortices (sensorimotor areas),
  through the reticular formation through inf
  middle cereb peduncle
• Control of voluntary movement

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ii. Afferent fibers from the spinal cord

• 1.Anterior spinocerebellar tract
• -Info from the muscles joints (receptors) via
  sup cereb peduncle to the cerebellarcortex
• 2. Posterior spinocerebellar tract
• -Info from the muscles joints (receptors) via
  inf cereb peduncle to the cerebellarcortex

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• 3.Cuneocerebellar tract
• -Conveys info of the muscles and joints of the
  upper limb and upper part of the thorax via the
  inf cereb peduncle to the cerebellar cortex
• 4. Vestibulocerebellar Tract
• Info From Semicircular Canals utricle/saccule
  Through Inferior Peduncle to the flocculonodular
  lobe via the inf cereb peduncle
• Conveys info of head position and movement

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• iii. Other afferent fibers
• -Conveys info from the midbrain ( red nucleus
  tectum) to the cerebellar cortex

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Cerebellar efferent fibers
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Efferent Pathways

• 3 pathways
• Globose-Emboliform-Rubral pathway
• Dentothalamic pathway
• Fastigial Vestibular pathway
• Fasigial Reticular pathway

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Efferent Pathways

• Arise From Cerebellar Nuclei
• Dentate nucleus (influences ipsilateral motor
  activity)
• Emboliform nucleus ()
• Globose Nucleus ()
• Fastigial Nucleus
• Through Superior Cerebellar Peduncle to
• Red Nucleus (Brainstem)
• -Thalamus
• -Motor Cortex

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• Through Inferior Cerebellar Peduncle to
• lateral vestibular nucleus ( influences
  ipsilateral extensor muscle tone)
• Reticular formation (influences ipsilateral
  muscle tone)

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Afferent and Efferent Projections
Thalamus
Red nucleus
Superior Cerebellar Peduncle
Middle Cerebellar Peduncle (pontocerebellar
fibers)
Inferior Cerebellar Nucleus (olivocerebellar
fibers)
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FUNCTION

• The cerebellum has several main functions
• coordinating skilled voluntary movements by
  influencing muscle activity,
• controlling equilibrium and muscle tone through
  connections with the vestibular system and the
  spinal cord and its gamma motor neurons.
• there is a somatotopic organization of body parts
  within the cerebellar cortex.
• In addition, the cerebellum receives collateral
  input from the sensory and special sensory
  systems.The vermis tends to control
  coordination and muscle
  tone of the trunk, whereas each cerebellar
  hemisphere controls motor coordination and muscle
  tone on the same side of the body.