Cerebellum

The Ventral/Anterior Spinocerebellar tract passes through the _________(superior/inferior) cerebellar peduncle and terminates mainly in the anterior lobe of the cerebellum The Dorsal/Posterior Spinocerebellar tract passes through the _________(superior/inferior) cerebellar peduncle and terminates mainly in the anterior lobe of the cerebellum

Ventral/Anterior: Superior Cerebellar Peduncle Dorsal/Posterior: Inferior Cerebellar Peduncle

Lateral Medullary Syndrome

*AKA Wallenberg Syndrome * * * *

Which of the cerebellar peduncles receives only afferent fibers?

Middle cerebellar peduncle

What are the three fiber types of the cerebellar cortex?

Mossy Climbing Parallel

All information to the cerebellum travels through which structures?

The cerebellar peduncles

Anterior Vermis Syndrome

* * * * *

Flocculonodular Lobe Syndrome

* * * * *

How do the olivocerebellar axons terminate in the cerebellum? A. Mossy fibers B. Climbing fibers C. Basket cell axons

B. Climbing fibers Remember that climbing fibers originate in the inferior olivary nucleus

The right cerebral cortex affects the function of the right cerebellar cortex T/F?

F! The cerebral cortex exerts its influence on the contralateral cerebellar cortex.

Which is the largest cerebellar peduncle?

Middle cerebellar peduncle

What is the name of the structure that is the most inferior part of the cerebellar vermis?

Nodulus

What type of cell is the only outflow from the cerebellar cortex?

Purkinje Cells

Vestibulocerebellar Tract

The vestibulocerebellar tract brings information from the vestibular nucleus to the flocculonodular lobe via the inferior cerebellar peduncle

The cerebellar cortex influences the action of the cerebellar nuclei through the axons of Purkinje cells that project from the cortex to the cerebellar nuclei. Direct excitation of Purkinje cells by parallel fibers would, momentarily, result in which of the following? (A) Decrease in thalamic activity with corresponding increase in cortical activity (B) Decrease in thalamic activity with corresponding decrease in cortical activity (C) Increase in thalamic activity with corresponding increase in cortical activity (D) Increase in thalamic activity with corresponding decrease in cortical activity (E) No change in thalamic activity and no change in cortical activity

(B) Decrease in thalamic activity with corresponding decrease The key to this answer is to recall that parallel fibers (the axons of granule cells) are glutaminergic and, therefore, excitatory to their targets, and that Purkinje cells are GABAergic and, therefore, inhibitory to their targets. Parallel fiber excitation of Purkinje cells results in inhibition of the cerebellar nuclear cells on which these Purkinje axons terminate. Since the efferents of the cerebellar nuclei are glutaminergic and therefore are excitatory to the thalamus, inhibition of these nuclear cells by Purkinje cells will decrease their activity and, consequently, decrease their influence on the thalamus. This results in a decrease in the activity of the thalamus, in the thalamocortical pathway, and in the activity of the motor cortex. It is also important to recall that the cerebellar nuclei receive excitatory inputs from the mossy and climbing fibers that are modulated by Purkinje cells.

Friedrich Ataxia

* * * * *

Posterior Vermis Syndrome

* * * * *

General facts about the cerebellum

*All tracts to and from the cerebellum travel through the cerebellar peduncles * * *Despite its size, the cerebellum contains about 1/2 of all the neurons in the CNS * * *

Corticopontocerebellar Pathway

*Originates in primary motor and sensor cortices *Descend to pons via internal capsule(pontine nuclei) *Pontine nuclei projects fibers across midline through the Middle Cerebellar peduncle into the contralateral cerebellar cortex *Fibers exit the cerebellar cortex through the Superior Cerebellar peduncle and cross the midline to enter the VL nucleus of the thalamus (Some fibers may also give off to the red nucleus) *The thalamus sends fibers back to the primary motor cortex

Describe the blood supply to the Cerebellum

*PICA: supplies inferior surface of the cerebellum, tonsils *AICA: Middle cerebellar peduncle, Flocculus, All deep cerebellar nuclei *SCA: Anterior lobe, superior part of vermis, Superior cerebellar peduncle

General functions of the cerebellum

*Planning and fine-tuning of skeletal muscle contractions * * * *

Ataxia

*defined as presence of abnormal, uncoordinated movements *disorder of coordination and rhythm *the rate, range, and force of movement are altered *Ataxia is often due to cerebellar damage but DOES NOT ALWAYS = cerebellar damage

The dorsal spinocerebellar tract, the ventral spinocerebellar tract, and the cuneocerebellar tract, in a general sense, show convergence in their projections to the cerebellum. Which of the following is the principal region within the cerebellum where these fibers converge 1. Anterior lobe 2. Posterior lobe 3. Flocculonodular lobe 4. Fastigial nucleus 5. Dentate nucleus

1. Anterior lobe One of the most important features of the anterior lobe of the cerebellum is that it receives major inputs from structures that mediate information concerning muscle spindle and golgi tendon organ activity (sometimes referred to as unconscious proprioception). The pathways that mediate unconscious proprioception include the dorsal and ventral spinocerebellar tracts and the cuneocerebellar tract. Accordingly, the cerebellar anterior lobe is sometimes referred to as the spinocerebellum. The fastigial and dentate nuclei receive their principal inputs from the cerebellar cortex, and their axons project out of the cerebellum. The posterior lobe receives few, if any, inputs from pathways that mediate unconscious proprioception information.

The cerebellar cortex is divided into how many layers? What are they from innermost to outermost?

3 layers Granule cell layer (innermost) Purkinje Cell layer Molecular (outermost/closest to the surface)

Climbing fibers originate in the medulla and synapse with Purkinje cells in the contralateral cerebellum. Each Purkinje cell in the cerebellum receives input from how many climbing fibers? A. 1 B. 2 C. 5 D. 10 E. Thousands

A. 1 Climbing fibers originate in the inferior olivary nucleus in the medulla and project to the contralateral cerebellum where they synapse with Purkinje fibers. Each climbing fiber may synapse with multiple Purkinje cells, but each Purkinje fiber receives input from only one climbing fiber. Climbing fibers carry somatosensory, visual, and cerebral cortical information. The other choices are incorrect

Which of the following statements best describes the fibers traveling through the cerebellar peduncles? A. Efferent fibers from the deep cerebellar nuclei exit the cerebellum mainly through the superior cerebellar peduncle. B. The middle cerebellar peduncle carries a mix of afferent and efferent fibers. C. Proprioceptive information from the spinal cord enters the cerebellum through the middle cerebellar peduncle. D. Motor information from spinal border cells enters the cerebellum through the inferior cerebellar peduncles. E. Efferents from the cerebellum to the inferior olivary nuclear complex travel through the superior cerebellar peduncle.

A. Efferent fibers from the deep cerebellar nuclei exit the cerebellum mainly through the superior cerebellar peduncle.

A patient delays initiation of movement, displays an uneven trajectory in moving her hand from above her head to touch her nose, and is uneven in her attempts to demonstrate rapid alternation of pronating and supinating movements of the hand and forearm. She probably has a lesion in the A. Hemispheres of the posterior cerebellar lobe B. Flocculonodular lobe of the cerebellum C. Vermal region of the anterior cerebellar lobe D. Fastigial nucleus E. Ventral spinocerebellar tract

A. Hemispheres of the posterior cerebellar lobe

A patient delays initiation of movement, displays an uneven trajectory in moving her hand from above her head to touch her nose, and is uneven in her attempts to demonstrate rapid alternation of pronating and supernating movements of the hand and forearm. Which of the following is the most likely locus of the lesion A. Hemispheres of the posterior cerebellar lobe B. Flocculonodular lobe of the cerebellum C. Vermal region of the anterior cerebellar lobe D. Fastigial nucleus E. Ventral spinocerebellar tract

A. Hemispheres of the posterior cerebellar lobe Hemispheres of the posterior cerebellar lobe -the classic appearance of a patient with a lesion of the cerebellar hemispheres is one in which voluntary and skilled movements are affected. They are uncoordinated and there are errors in the range, force, and direction of movement. The relationships between the cerebellum and the motor regions of the cerebral cortex have been disrupted. Lesions of other regions such as the flocculonodular lobe, vermal region of the anterior cerebellar cortex, or fastigial nucleus produce different symptoms (disturbances of balance, muscle tone, or nystagmus). Although pure lesions limited to the ventral spinocerebellar tract have not been reported, it is likely that such a lesion could not account for the symptoms indicated in this question. Information carried by this tract concerns activity of golgi tendon organs of muscles of the lower limbs.

Climbing fibers carry somatosensory, visual, and cerebral cortical information to the contralateral cerebellum. They form synapses with multiple Purkinje cells, though each Purkinje cell receives input from only 1 climbing fiber. The cell bodies of climbing fibers originate where? A. Inferior olivary nucleus B. Superior olivary nucleus C. Mamillary body D. Medial vestibular nucleus E. Pontine nuclei

A. Inferior olivary nucleus

The clinical signs of cerebellar hemisphere disease generally occur on the same side as the lesion. A. True. B. False.

A. True The cerebellar cortex indirectly projects to and receives information from the ipsilateral spinal cord. Therefore, lesions affect the same side of the body.

The spinocerebellum contains the... A. vermis and intermediate zone of the anterior and posterior lobes. B. Vermal and floccular parts of the flocculonodular lobe. C. Lateral portions of the cerebellum. D. Posterior lobe and interposed nuclei. E. Anterior lobe and dentate nuclei.

A. vermis and intermediate zone of the anterior and posterior lobes.

Which of the cerebellar peduncles are primarily afferent (input), which are primary efferent (output)?

Afferent: input into the cerebellum travels primarily in ICP and MCP Efferent: output from the cerebellum travels primarily in the SCP *MCP = exclusively afferent

What are three lobes of the cerebellum?

Anterior lobe Posterior lobe Flocculonodular lobe *The picture is showing a midsagittal view

Cerebellar lesions result in a characteristic type of irregular uncoordinated movement, called?

Ataxia

The right cerebral cortex affects the function of the right cerebellar cortex. A. True. B. False.

B. False. The cerebral cortex exerts its influence on the contralateral cerebellar cortex. The pontine nuclei send their axons across the midline to synapse in the opposite cerebellar hemisphere.

In relation to the cytoarchitecture of the cerebellar cortex, which of the following is true? A. The Purkinje cell axon is an afferent pathway of the cerebellum. B. Mossy fibers synapse on Golgi cell and granule cell dendrites in the cerebellar glomerulus. C. Basket cells synapse in a one-to-one ratio with Purkinje cells. D. Golgi cells provide excitatory input to the cerebellar glomerulus. E. Climbing fi bers provide feedback about motor o utput of the dentate nucle

B. Mossy fibers synapse on Golgi cell and granule cell dendrites in the cerebellar glomerulus.

What structure attaches the cerebellum to the brain stem? A. Cerebral peduncles. B. Vermis. C. Cerebellar peduncles. D. Tonsil.

C. Cerebellar peduncles. The inferior, middle, and superior cerebellar peduncles attach the cerebellum to the medulla and pons. In general, the inferior and middle cerebellar peduncles are formed by axons afferent to the cerebellum, while the superior cerebellar peduncle is formed by efferent cerebellar fibers.

Which of the following statements about the spinocerebellar loop is correct? A. Proprioceptive information from the spinal cord enters the cerebellum and terminates in the posterior lobe. B. The coordination of truncal movements happens primarily in the anterior lobe. C. The cerebellum coordinates limb movements on the ipsilateral side of the body. D. The emboliform and globose nuclei project primarily to the red nucleus. E. The fastigial nucleus sends projections to the ipsilateral vestibular nuclei.

C. The cerebellum coordinates limb movements on the ipsilateral side of the body.

Olivocerebellar Tract

Carries information from the olivary nucleus to the CONTRALATERAL cerebellar cortex via the inferior cerebellar peduncle

The ____________ (parallel/perpendicular) fibers of the granule cell layer run ____________ (parallel/perpendicular) to the purkinje cells

Cerebellar granule cells send parallel fibers that run perpendicular to the flat (2D) purkinje cells

Which part of the cerebellum is prone to herniation through the foramen magnum because of mass lesions or elevated intracranial pressure?

Cerebellar tonsils (tonsillar herniation)

Climbing fibers provide a ______________ (direct/indirect) excitatory input to purkinje cells Mossy fibers provide a ______________ (direct/indirect) excitatory input to purkinje cells

Climbing: Direct Mossy: Indirect Climbing fibers synapse directly on Purkinje cells, whereas mossy fibers act through granule cells.

What cells comprise the sole output of the cerebellar cortex? What cells comprise the sole output of the entire cerebellum?

Cortex: Purkinje Cells Entire Cerebellum: Deep Cerebellar Nuclei

Which tract is considered to be the upper limb equivalent of Dorsal Spinocerebellar Tract?

Cuneocerebellar Tract

What are the structural and functional relations between the cerebellar cortex and the deep, or central, nuclei? A. Deep nuclei receive input from Purkinje cells. B. Deep nuclei receive input from mossy fibers. C. Deep nuclei receive input from climbing fibers. D. All of the above.

D. All of the above. Purkinje cells synapse in one of the four deep nuclei and have an inhibitory effect. The mossy and climbing fibers as they enter the cerebellum give off collaterals that excite the cells in the deep cerebellar nuclei.

Ataxia is defined as: A. Inability to perform rapidly alternating movements. B. Error in the range of movement. C. Lack of continuity in the execution of movements. D. Error in the rate, force, and direction of movement. E. Muscle weakness.

D. Error in the rate, force, and direction of movement.

Which of the following statements about the wiring of the cerebrocerebellar loop is correct? A. The pontine nuclei receive projections from the contralateral cerebral cortex and, in turn, project to the contralateral cerebellar cortex. B. Input to the neocerebellum comes primarily from the vestibular nuclei. C. Climbing fibers from the ipsilateral inferior olivary nuclear complex project to the neocerebellar cortex. D. Output from the neocerebellum is through the dentate nucleus to the red nucleus and the thalamus. E. The neocerebellum has a role in the generation of language and cognition

D. Output from the neocerebellum is through the dentate nucleus to the red nucleus and the thalamus.

Name the Deep Cerebellar Nuclei from lateral to medial Which of the nuclei are often collectively referred to as the interposed nuclei? Which is the largest deep cerebellar nucleus?

Dentate, Emboliform, Globose, and Fastigial Mnemonic: Don't Eat Greasy Food Interposed: Emboliform, Globose Largest: Dentate

Spinocerebellar Tracts

Dorsal/Posterior Spinocerebellar: *Unconscious proprioception Cuneocerebellar * Ventral/Anterior Spinocerebellar * Rostral Spinocerebellar *Anterior: This is how the cerebellum receives a "copy" of the motor information sent to the LMN system of the spinal cord Together, these four tracts convey a complete picture of the body in motion to the cerebellum, where that information is then used to fine-tune and adjust movement as well as to facilitate motor learning

"Afferent" fibres from olivary nucleus to cerebellum (ICP/MCP =inferior/middle cerebellar peduncle ) A-------Mossy fibres--------ICP---------crossed------------Purkinje cells B-------climbing fibres------ICP--------uncrossed---------purkinje cells C-------climbing fibres------ICP--------uncrossed---------granule cells D--------Mossy fibres------ MCP---------crossed------------Granule cells E--------Climbing fibres----ICP---------crossed------------Purkinje cells

E--------Climbing fibres----ICP---------crossed------------Purkinje cells

What are the five cell types of the cerebellar cortex?

Granule Golgi Purkinje Basket Stellate

What is the only excitatory neuron within the cerebellar cortex?

Granule Cell

Climbing fibers originate exclusively from which brain structure?

Inferior olivary nucleus (located in the medulla oblongata)

Folia

Leaflike wrinkles(gyri)/parallel folds on the surface of the cerebellum

Mossy fibers form __________(excitatory/inhibitory) inputs on granule cells, which form __________(excitatory/inhibitory) synapses on Purkinje cells, which form __________(excitatory/inhibitory) outputs on the deep cerebellar nuclei

Mossy: excitatory Granule cells: excitatory Purkinje: inhibitory

The cerebellum is composed of _________ (gray/white) matter on the outside and _________ (gray/white) matter on the inside

Outside: Gray matter (makes up the cerebellar cortex) Inside: White matter (includes the cerebellar nuclei)

The inferior cerebellar peduncle is composed of ________ + __________

Restiform body and Juxtarestiform body (The ICP is often referred to as the restiform body)

Describe the "homunculus" of the cerebellar cortex

Similar to the cerebral cortex, representations of areas of the body can be mapped on the cerebellar cortex Vermis: Axial/truncal muscles Anterior lobe: Note that the body is represented more than oncelay

Afferent Connections of the Cerebellum

Spinal Cord -the spinal cord supplies the cerebellum with IPSILATERAL unconscious proprioceptive information about position of muscles -these are known as the Spinocerebellar tracts -the projections of these pathways are directed primarily to the vermis and paravermis. Therefore those areas are referred to as the Spinocerebellum Cortex -the cortex communicates with the CONTRALATERAL cerebellum via a relay in the basilar pons -this is known as the Corticopontocerebellar tract Vestibular System -vestibular information concerning the position of the head in space is sent to the cerebellum via the Inferior Cerebellar Peduncle *These fibers comprise the mossy fibers in the cerebellar cortex* Inferior Olive *These fibers comprise the climbing fibers in the cerebellar cortex*

Unlike the cerebral cortex, the cerebellum receives input from, and controls output to, the ipsilateral side of the body, and damage to the cerebellum therefore results in deficits to the ipsilateral side of the body T/F?

T!

What relationship does the cerebellum have with the fourth ventricle?

The cerebellum forms the roof of/ lies over the fourth ventricle

What is the function of the flocculonodular lobe?

The flocculonodular lobe is involved in the maintenance of posture/balance and eye movements

What are the three functional divisions of the cerebellum?

The spinocerebellum The cerebrocerebellum The vestibulocerebellum Spinocerebellum: