cerebellum

• It is situated in the posterior cranial fossa and is covered superiorly by the tentorium cerebelli.

• It coordinates movement and postural control by comparing actual motor output with the intended movement and then adjusting movement as necessary

• It is the largest part of the hindbrain and lies posterior to the fourth ventricle, the pons, and the medulla oblongata

• It consists of two cerebellar hemispheres joined by a narrow median vermis

cerebellum

• It is situated in the posterior cranial fossa and is covered superiorly by the tentorium cerebelli.

cerebellum

• It coordinates movement and postural control by comparing actual motor output with the intended movement and then adjusting movement as necessary

cerebellum

• It is the largest part of the hindbrain and lies posterior to the fourth ventricle, the pons, and the medulla oblongata

cerebellum

• It consists of two cerebellar hemispheres joined by a narrow median vermis

cerebellum

The cerebellum is composed of an outer covering of gray matter called the ____ and inner white matter

cortex

small amount of white matter in the vermis which closely resembles the trunk and branches of a tree

Arbor vitae:

• Cerebellar cortex is divided into three layers:

1. Molecular layer (outer stellate, inner basket cells)

2. Purkinje cell layer (Golgi type I neurons)

3. Granular layer (granule cells)

• Afferents to cerebellar cortex:

• Climbing fibers

• Mossy fibers

originate in the spinal cord (spinocerebellar

tracts) and in the brainstem.

Mossy fibers

synapse with interneurons that convey information to

Purkinje cells

Mossy fibers

Convey somatosensory, arousal, equilibrium, and cerebral cortex motor information to the

cerebellum

Mossy fibers

arise from the inferior

olivary nucleus in the

Medulla

  

Climbing fibers

synapse with Purkinje

dendrites

Climbing fibers

convey information

regarding movement

errors to the cerebellum.

Climbing fibers

Functional Areas of Cerebellar Cortex

Cortex of vermis

Intermediate zone

Lateral zone

enumerate the cerebellar peduncles

superior cerebellar peduncles

middle cerebellar peduncles

inferior cerebellar peduncles

• connect the cerebellum to the midbrain

• Superior cerebellar peduncles (Brachium conjunctivum)

• connect the cerebellum to the pons

• Middle cerebellar peduncles (Brachium pontis)

• connect the cerebellum to the medulla oblongata.

•  Inferior cerebellar peduncles (Restiform body)

The cerebellum is divided into three main lobes which are:

the anterior lobe, the middle lobe, and the flocculonodular lobe.

may be seen on the superior surface of the cerebellum and is separated from the middle lobe by a wide Vshaped fissure called the primary fissure

The anterior lobe

The anterior lobe may be seen on the superior surface of the cerebellum and is separated from the middle lobe by a wide Vshaped fissure called the?

primary fissure

• It is the largest part of the cerebellum, is situated between the primary and uvulonodular fissures.

• The posterior lobe

• It is situated posterior to the uvulonodular fissure

• The flocculonodular lobe

enumerate the intracerebellar nuclei

dentate nucleus

emboliform nucleus

globose nucleus

fastigial nucleus

• •  is the largest of the cerebellar nuclei. It has the shape of a crumpled bag with the opening facing medially. It projects to the contralateral red nucleus and the ventrolateral (VL) thalamic nucleus.

• Dentate nucleus

• • is ovoid and is situated medial to the dentate nucleus, partially covering its hilus

• Emboliform nucleus

• • consists of one or more rounded cell groups that lie medial to the emboliform nucleus. Together with emboliform, they collectively known as interposed nuclei. They project to the contralateral red nucleus (the origin of the rubrospinal tract).

• Globose nucleus

• • lies near the midline in the vermis and close to the roof of the fourth ventricle; it is larger than the globose nucleus. It projects to the vestibular nuclei and the reticular formation.

• Fastigial nucleus

Functional regions of the Cerebellum

• Human movements can be categorized into three broad classes:

• Equilibrium

• Gross movements of the limbs

• Fine, distal, voluntary movements

Functional names for lobes

• Vestibulocerebellum → Flocculonodular lobe

• Spinocerebellum → Anterior lobe

• Cerebrocerebellum → Posterior lobe

• • receives information directly from vestibular receptors and connects reciprocally with the vestibular nuclei

  • Balance and equilibrium

  • influences eye movements and postural muscles.

• Vestibulocerebellum (flocculonodular lobe, Archicerebellum)

• • receives information directly from vestibular receptors and connects reciprocally with the vestibular nuclei

• Vestibulocerebellum (flocculonodular lobe, Archicerebellum)

• Balance and equilibrium

• Vestibulocerebellum (flocculonodular lobe, Archicerebellum)

• influences eye movements and postural muscles.

• Vestibulocerebellum (flocculonodular lobe, Archicerebellum)

• • control ongoing movement via brainstem descending tracts; receives proprioceptive information from muscle spindles, as well as visual and auditory information

  • coordinates stereotype and gross limb movements.

• Spinocerebellum (anterior lobe, Paleocerebellum)

• • control ongoing movement via brainstem descending tracts; receives proprioceptive information from muscle spindles, as well as visual and auditory information

• Spinocerebellum (anterior lobe, Paleocerebellum)

• coordinates stereotype and gross limb movements.

• Spinocerebellum (anterior lobe, Paleocerebellum)

• • Coordination of voluntary movements

  • Planning of movements and Timing

• Cerebrocerebellum (posterior lobe, Neocerebellum)

• • Coordination of voluntary movements

• Cerebrocerebellum (posterior lobe, Neocerebellum)

• Planning of movements and Timing

• Cerebrocerebellum (posterior lobe, Neocerebellum)

General Function of the Cerebellum

• The cerebellum receives afferent information from different structures for the following functions: (where are they from?)

  • Voluntary movement →

  • Balance →

  • Integration with vision →

• Voluntary movement → cerebral cortex and from muscle, tendons, and joints

• Balance → vestibular nerve

• Integration with vision → tectocerebellar tract

General Function of the Cerebellum

• The cerebellum receives afferent information from different structures for the following functions: (where is this from?)

  • Voluntary movement →

• Voluntary movement → cerebral cortex and from muscle, tendons, and joints

General Function of the Cerebellum

• The cerebellum receives afferent information from different structures for the following functions: (where is this from?)

  • Balance →

• Balance → vestibular nerve

General Function of the Cerebellum

• The cerebellum receives afferent information from different structures for the following functions: (where is this from?)

  • Integration with vision →

• Integration with vision → tectocerebellar tract

summary of inputs to the cerebellum

• executive

• feedback

• learning

• ____ relayed from widespread parts of cerebral cortex in the frontal and parietal lobes via the pontine nuclei: conveys the commands for (motor) behavior

• “Executive” signals

• “Executive” signals relayed from widespread parts of cerebral cortex in the frontal and parietal lobes via the ______ : conveys the commands for (motor) behavior

• pontine nuclei

• _____ from proprioceptive systems: conveys sensory information about ongoing behavior

• “Feedback” signals

• _____ derived from the inferior olivary nucleus of the medulla: facilitates adaptation (error correction)

• “Learning” signals

• “Learning” signals derived from the ______ : facilitates adaptation (error correction)

• inferior olivary nucleus of the medulla

summary of outputs from the cerebellum

ascending output

descending output

• is directed toward thalamocortical circuits

•  Dentate nucleus (and interposed nuclei) sends its axons out of the cerebellum through the superior cerebellar peduncle, which then decussate → contralateral ventral lateral complex of the thalamus

•  “ascending” output

• is directed toward brainstem circuits

  • Fastigial nuclei project to medial upper motor neuron systems in the brainstem reticular formation

  • Each deep cerebellar nucleus also projects to the red nucleus → provides feedback signals to the inferior olivary nucleus

• “descending” output

TRUE OR FALSE: the cerebellum has no direct neuronal connections with the lower motor neurons

TRUE

TRUE OR FALSE:  The cerebellum functions as coordinator of precise movements

TRUE

TRUE OR FALSE:  The cerebellum functions as coordinator of gross movements

FALSE

TRUE OR FALSE: The cerebellum continuously compare the output of the motor area of the cerebral cortex with the proprioceptive information received from the site of muscle action

TRUE

TRUE OR FALSE: The cerebellum intermittently compare the output of the motor area of the cerebral cortex with the proprioceptive information received from the site of muscle action

FALSE

TRUE OR FALSE: Bring about the necessary adjustments by influencing the activity of the lower motor neurons

TRUE

TRUE OR FALSE: Bring about the necessary adjustments by ignoring the activity of the lower motor neurons

FALSE

• TRUE OR FALSE: The cerebellum controls the timing and sequence of firing of the alpha and gamma motor neurons

TRUE

• TRUE OR FALSE: The cerebellum controls the timing and sequence of firing of the alpha motor neurons only

FALSE

• TRUE OR FALSE: The cerebellum is believed to inhibit the agonist muscles and stimulate the antagonist muscles, thus limiting the extent of voluntary movement

TRUE

• TRUE OR FALSE: The cerebellum is believed to stimulate the agonist muscles and inhibit the antagonist muscles, thus limiting the extent of voluntary movement

FALSE dapat inhibit niya agonist para di sumobra movement

• is general, comprehensive term used to describe loss of muscle coordination as a result of cerebellar pathology.

  • uncoordinated voluntary movements. movements are normal strength, jerky, inaccurate, and not caused by spasticity or contracture

  • Truncal ataxia

  • Limb ataxia

  • Hand ataxia

• Cerebellar Ataxia

• generalized muscle weakness associated with cerebellar lesions.

• Asthenia:

• a disorder of the motor component of speech articulation. The characteristics of cerebellar dysarthria are referred to as scanning speech

• Dysarthria:

• an impaired ability to perform rapid alternating movements

• Dysdiadochokinesia:

• an inability to judge the distance or range of a movement. It

  • Hypermetria: an overestimation of the required range needed

  • Hypometria: an underestimation of the required range needed to reach an object or goal.

• Dysmetria:

• the loss of ability to associate muscles together for complex movements.

• Asynergia:

• describes a movement performed in a sequence of component parts rather than as a single, smooth activity

• Dyssynergia (movement decomposition)

• a decrease in muscle tone. A diminished resistance to passive movement will be noted, and muscles may feel abnormally soft and flaccid.

• Hypotonia:

• a rhythmic, quick, oscillatory, back-and forth movement of the eyes. It is typically apparent as the eyes move away from midline to fix on an object in either the medial or lateral

• Nystagmus:

• the loss of the check reflex, or check factor, which functions to halt forceful active movements when resistance is eliminated

• Rebound phenomenon:

• involuntary oscillatory movement resulting from alternate contractions of opposing muscle groups.

  • Intention tremor, or kinetic tremor: occurs during voluntary motion of a limb and tends to increase as the limb nears its intended goal or speed is increased. Intention tremors are diminished or absent at rest.

  • Postural (static) tremor: may be evident by back-and-forth oscillatory movements of the body while the patient maintains a standing posture.

  • Titubation: typically refers to rhythmic oscillations of the head (side to-side or forward-and-backward movements, or the movements may have a rotary component); however, the term is also less frequently used to refer to axial involvement of the trunk

• Tremor:

• occurs during voluntary motion of a limb and tends to increase as the limb nears its intended goal or speed is increased. Intention tremors are diminished or absent at rest.

• Intention tremor, or kinetic tremor:

• may be evident by back-and-forth oscillatory movements of the body while the patient maintains a standing posture.

• Postural (static) tremor:

• typically refers to rhythmic oscillations of the head (side to-side or forward-and-backward movements, or the movements may have a rotary component); however, the term is also less frequently used to refer to axial involvement of the trunk

• Titubation: