Cerebellum Flashcards
•Function of The cerebellum:
.
.
•The cerebellum:
•Coordinates gait
•Maintains posture,
•Controls muscle tone and voluntary muscle activity
.
•Is the cerebellum able to initiate muscle contraction
No
The cerebellum is neuron-rich, containing —% of the brain’s neurons organized in a dense cellular layer, and its surface area when unfolded is nearly —% of the surface area of the cerebrum.
The cerebellum is neuron-rich, containing 80% of the brain’s neurons organized in a dense cellular layer, and its surface area when unfolded is nearly 75% of the surface area of the cerebrum.
Fore brain is the largest part of the brain, most of which is ————. Other structures found in the forebrain include the ———
Mid brain (mesencephalon) connects the ——- and the ——— and functions include; ———-
• Hind brain links the forebrain and mid brain to the ———. It is made up of the ——-,——-which maintains balance and equilibrium, movement coordination and the conduction of sensory information) and ———- (medulla oblongata which has autonomic functions in controlling breathing, heart rate and digestion)
Fore brain is the largest part of the brain, most of which is cerebrum hemisphere ( telencephalon). Other structures found in the forebrain include the thalamus, the hypothalamus and the limbic system (diencephalon )
Mid brain (mesencephalon) connects the forebrain and the hind brain and functions include; auditory and visual responses as well as motor function
• Hind brain links the forebrain and mid brain to the spinal cord. It is made up of the metencephalon (pon and cerebellum which maintains balance and equilibrium, movement coordination and the conduction of sensory information) and myelencephalon (medulla oblongata which has autonomic functions in controlling breathing, heart rate and digestion)
In Latin, the word cerebellum means ———’.
In Latin, the word cerebellum means little brain’.
the cerebellum accounts for approximately —% of the brain’s volume,
the cerebellum accounts for approximately 10% of the brain’s volume,
The cerebellum is located in the ——— cranial fossa
It is located posterio-superiorly to the —— tucked underneath the cerebral hemispheres underlying its —— and ——- lobes
The cerebellum is separated from the pons and medulla by the ——— and the ———.
The cerebellum is located in the posterior cranial fossa
It is located posterio-superiorly to the brain stem tucked underneath the cerebral hemispheres underlying its occipital and temporal lobes
The cerebellum is separated from the pons and medulla by the cerebral aqueduct of Sylvius and the fourth ventricle.
Cerebellar cortex
The cerebellar cortex is the superficial layer of — matter consisting mainly of nerve —— and ——.
Its cortical surface appears as finely spaced ——- grooves, in striking contrast to the broad irregular convolutions of the cerebral cortex.
Within the folds are large number of thin neurons regularly arranged, this accommodating about —% of the total number of neurons in the brain even when the cerebellum is 10% of the brain’s volume
Cerebellar cortex
The cerebellar cortex is the superficial layer of gray matter consisting mainly of nerve cell bodies and dendrites.
Its cortical surface appears as finely spaced parallel grooves, in striking contrast to the broad irregular convolutions of the cerebral cortex.
Within the folds are large number of thin neurons regularly arranged, this accommodating about 50% of the total number of neurons in the brain even when the cerebellum is 10% of the brain’s volume
Microscopically within the thin layer of cerebellar cortex is;
Microscopically within the thin layer of cerebellar cortex is;
• Molecular laver (external)
• Purkinje layer (middle)
• Granular layer (internal)
Cerebellar medullary core
• Underneath the gray matter of the cortex lies white matter called the ——-
• Underneath the gray matter of the cortex lies white matter called the arbor
vitae
• Made up largely of myelinated nerve fibers running to and from the cortex.
Arbor vitae
•In latin “ ———” it is the white matter of the white matter of cerebellum.
•It is so called because of the tree like
appearance
•It brings ——- and —— sensation to and from cerebellum.
Arbor vitae
•In latin “ tree of life” it is the white matter of the white matter of cerebellum.
•It is so called because of the tree like
appearance
•It brings sensory and motor sensation to and from cerebellum.
Deep cerebellar nuclei
The cerebellum has deep cerebellar which are:
Deep cerebellar nuclei
The cerebellum has deep cerebellar nuclei
(Dentate nucleus;
Emboliform and
Globose nuclei (interposed nucleus);
Fastigial nuclei;
embedded within the center of the white matter.
——— and ——— nuclei (interposed nucleus);
Emboliform and
Globose nuclei (interposed nucleus);
M
Cerebellar hemispheres
The cerebellum is divided into how many cerebellar hemispheres seperated by a narrow midline zone called——-
located along the mid-sagittal plane of the cerebellum.
The cerebellum is divided into two cerebellar hemispheres seperated by a narrow midline zone (vermis)
located along the mid-sagittal plane of the cerebellum.
Lobes
1. ——— lobe
(above the ——— fissure)
2. ——— lobe (below the ——- fissure)
3. ——— lobe (below the posterior fissure).
These lobes divide the cerebellum from ——— to ——— (top to bottom).
Lobes
Anterior lobe
(above the primary fissure)
Posterior lobe (below the primary fissure)
Flocculonodular lobe/ vestibulocerebellum / archicerebellum (below the posterior fissure).
These lobes divide the cerebellum from rostral to caudal (top to bottom).
Each lobe is further subdivided into ——.
Lobules
Two major fissures running mediolaterally divide the cerebellar cortex into three primary lobes
1. —— fissure separates the corpus cerebelli into a —— lobe and an —— lobe
2. ——— fissure separates the ——— lobe from the ——- lobe.
Two major fissures running mediolaterally divide the cerebellar cortex into three primary lobes
Primary fissure separates the corpus cerebelli into a posterior lobe and an anterior lobe
Posterolateral fissure separates the flocculonodular lobe from the posterior lobe.
——— is The largest and deepest fissure in the cerebellum
Horizontal fissure
Horizontal fissure
• It divides the posterior lobe of the cerebellum into an ——— and a ——- portion
The largest and deepest fissure in the cerebellum
• It divides the posterior lobe of the cerebellum into an upper and a lower portion (superior
posterior lobe and inferior posterior lobe)
Functional Zones
•The cerebellum can be divided by function into three functional areas/zones, the:
Functional Zones
•The cerebellum can be divided by function into three functional areas/zones, the:
• Cerebrocerebellum
•Spinocerebellum
•Vestibulocerebellum
Cerebrocerebellum
• Largest division, formed by the ——— hemispheres.
• It is involved in ———-
• It receives inputs from the cerebral cortex and ——— nuclei and sends outputs to the ——- and —— nucleus.
•This area also regulates coordination of muscle activation and is important in visually guided
movements.
Cerebrocerebellum
• Largest division, formed by the lateral hemispheres.
• It is involved in planning movements and motor learning.
• It receives inputs from the cerebral cortex and pontine nuclei and sends outputs to the thalamus and red nucleus.
•This area also regulates coordination of muscle activation and is important in visually guided
movements.
Spinocerebellum
•Comprised of the —— and ——— zone of the cerebellar hemispheres.
° It is involved in ———.
•It also receives proprioceptive information.
Spinocerebellum
•Comprised of the vermis and intermediate zone of the cerebellar hemispheres.
° It is involved in regulating body movements by allowing for error correction.
•It also receives proprioceptive information.
Vestibulocerebellum
•The functional equivalent to the ——— lobe.
° It is involved in controlling ———
•It receives inputs from the ——— system, and sends outputs back to the ——— nuclei.
Vestibulocerebellum
•The functional equivalent to the flocculonodular lobe.
° It is involved in controlling balance and ocular reflexes, mainly fixation on a target.
•It receives inputs from the vestibular system, and sends outputs back to the vestibular nuclei.
Functional Longitudinal Zones
Specific cerebellar afferent/efferent fibers are distributed to different zones of the cerebellum.
The four different zones are;
Functional Longitudinal Zones
Specific cerebellar afferent/efferent fibers are distributed to different zones of the cerebellum.
The four different zones are;
• Medial (Vermal) zone
• Intermediate (paravermal)
zone
• Lateral zone
• Flocculonodular zone
Functional longitudinal zones
Medial zone- located within the ——-
Directly lateral to the vermis-the ——- zone.
More laterally- the ——— zone ().
The ———- zone is within the Flocculonodular lobe
Medial zone- located within the vermis
Directly lateral to the vermis-the intermediate zone.
More laterally- the lateral zone (Note: there are no clear morphological borders between the intermediate zone and the lateral hemisphere that are visible from a gross specimen).
The Flocculonodular zone is within the Flocculonodular lobe
The vermal zone is found along the length of the vermis.
• This region is responsible for the ———.
• Information regarding muscle tone of the ——, ——— muscles, —— and ——— would be transmitted to this region from the ——— tracts.
.
The vermal zone is found along the length of the vermis.
• This region is responsible for the maintaining balance.
• Information regarding muscle tone of the hips, thoracoabdominal muscles, shoulders and neck would be transmitted to this region from the spinocerebellar tracts.
.
• The medial zone (also called ———) - receives proprioceptive in put from the dorsal columns of the spinal cord (including the ——— tract); from the ——— nerve;
from the ——— and ——— systems.
• The function of the paleocerebellum is ———-.
The vermal zone is found along the length of the vermis.
• This region is responsible for the maintaining balance.
• Information regarding muscle tone of the hips, thoracoabdominal muscles, shoulders and neck would be transmitted to this region from the spinocerebellar tracts.
• The medial zone (paleocerebellum) - receives proprioceptive in put from the dorsal columns of the spinal cord (including the spinocerebellar tract); from the trigeminal nerve;
from the visual and auditory systems.
• The function of the paleocerebellum is unconscious
proprioception and muscle tone.
The intermediate zone- receives inputs from the distal portions of ——— thru the ——— tract.
NB: The ——— and the intermediate zone forms the
spinocerebellum
The intermediate zone- receives inputs from the distal portions of limbs thru the spinocerebellar tract.
Sinocerebelum
to moder and premotor dorices plannig
NB: The vermis and the intermediate zone forms the
spinocerebellum
Intermediate zone
.
• Its regulatory activity is achieved by which nuclei.
•This portion of the cerebellum is involved in skilled, volitional movements.
• Its regulatory activity is achieved by the interposed (globose & emboliform)
nuclei.
•—— is the portion of the cerebellum is involved in skilled, volitional movements.
.
Intermediate zone
The lateral zone- largest part in humans (also called——-/——-).
• It receives input exclusively from the cerebral cortex and sends output mainly to the ———- thalamus.
It is involved:
•
The lateral zone- largest part in humans (cerebrocerebellum/ neocerebellum).
• It receives input exclusively from the cerebral cortex and sends output mainly to the ventrolateral thalamus.
It is involved:
• in planning a movement that is about to occur;
• in evaluating sensory information for action;
• a number of cognitive functions, such as determining the verb which best fits with a certain noun.
The smallest region- the flocculonodular zone (also called———-).
• Its primary connections are with the ——— nuclei of the brain stem.
• It participates mainly in ———
The smallest region- the flocculonodular zone (vestibulocerebellum).
• Its primary connections are with the vestibular nuclei of the brain stem.
• It participates mainly in balance and spatial orientation.
• The ——— nuclei are the most central pair of cerebellar nuclei
Fastigial
Fastigial nucleus
• The fastigial nuclei (FN) are the most central pair of cerebellar nuclei and are associated with the vermis.
• They are found along the ——- of the cerebellum.
• They receive ——— and ——— afferents from the vermis, and project to the spinal cord (via the —— nuclei) and the ———thalamic nucleus.
Fastigial nucleus
• The fastigial nuclei (FN) are the most central pair of cerebellar nuclei and are associated with the vermis.
• They are found along the midline of the cerebellum.
• They receive spinocerebellar and labyrinthine afferents from the vermis, and project to the spinal cord (via the vestibular nuclei) and the ventral lateral thalamic nucleus.
Fastigial nucleus
•This pathway eventually goes to the ——— gyrus, which sends its efferent fibers to the ——— and ——— muscles for maintenance of balance.
Fastigial nucleus
•This pathway eventually goes to the precentral gyrus, which sends its efferent fibers to the proximal and trunk muscles for maintenance of balance.
Globose and Emboliform Nuclei
• Via the ———- tract, proprioceptive impulses from the paravermis are conveyed to the ——— thalamic nucleus () and the —— nucleus ().
Globose and Emboliform Nuclei
• Via the interpositorubrothalamic tract (rubro = red nucleus), proprioceptive impulses from the paravermis are conveyed to the ventral lateral thalamic nucleus (VLN) and the red nucleus (RN).
Globose and Emboliform Nuclei
• Via the interpositorubrothalamic tract (rubro = red nucleus), proprioceptive impulses from the paravermis are conveyed to the ventral lateral thalamic nucleus (VLN) and the red nucleus (RN).
• The VLN then relays information to the ——- gyrus (Brodmann —), which sends regulatory signals down the lateral ——— tract to the distal muscles;
• while the Red nucleus arbitrates the management of the ——— muscles via the ——— tract.
Globose and Emboliform Nuclei
• Via the interpositorubrothalamic tract (rubro = red nucleus), proprioceptive impulses from the paravermis are conveyed to the ventral lateral thalamic nucleus (VLN) and the red nucleus (RN).
• The VLN then relays information to the precentral gyrus (Brodmann 4), which sends regulatory signals down the lateral corticospinal tract to the distal muscles;
• while the RN arbitrates the management of the distal flexor muscles via the rubrospinal tract.
• The ——— nucleus is the largest of the cerebellar nuclei
Dentate
Dentate nucleus
• The dentate nucleus is the largest of the cerebellar nuclei and is situated in the ——- hemispheres.
• It resembles a ———- with its open end facing ——.
Dentate nucleus
• The dentate nucleus is the largest of the cerebellar nuclei and is situated in the lateral hemispheres.
• It resembles a crushed paper bag with its open end facing anteromedially.
Dentate nucleus
• Unlike the other nuclei, the dentate nucleus partially encloses bundles of white matter that form the ——-/ and the ——— tracts.
• The dentate nucleus is extremely important for the regulation of many aspects of ——— activity, namely its timing, planning and inception.
Dentate nucleus
• Unlike the other nuclei, the dentate nucleus partially encloses bundles of white matter that form the dentatorubrothalamic and the dentatoolivary tracts.
• The dentate nucleus is extremely important for the regulation of many aspects of voluntary motor activity, namely its timing, planning and inception.
Cerebellar peduncles
The cerebellum is connected to the brain stem by three peduncles.
The cerebellum is connected to the brain stem by three peduncles.
• Superior cerebellar peduncle
• Middle cerebellar peduncle
• Inferior cerebellar peduncle
The superior cerebellar peduncle (brachium conjunctivum) connects the cerebellum to the ———.
• It sends efferent fibers mainly to the —— and —— nucleus.
• It receives afferent fibers from the ———— tract
The superior cerebellar peduncle (brachium conjunctivum) connects the cerebellum to the midbrain.
• It sends efferent fibers mainly to the thalamus and red nucleus.
• It receives afferent fibers from the ventral spinocerebellar tract
Superior cerebellar peduncle
Superiorly, the superior cerebellar peduncles are connected together by the ————
• Inferiorly, they form the upper lateral boundaries of the ——— ventricle, but as they ascend they converge on the dorsal aspect of the ventricle and thus assist in forming its ——.
The ——— cerebellar peduncle/ brachium pontis is the largest of the peduncles.
The middle cerebellar peduncle
The middle cerebellar peduncle/ brachium pontis is the largest of the peduncles.
• They are paired structures (left and right)
that connect the cerebellum to the ——-
• It primarily contains afferents from the ——— nuclei.
The middle cerebellar peduncle/ brachium pontis is the largest of the peduncles.
• They are paired structures (left and right)
that connect the cerebellum to the pons
• It primarily contains afferents from the pontine nuclei.
The middle cerebellar peduncle( also called———) is the largest of the peduncles.
.
brachium pontis.
The superior cerebellar peduncle (also called——-)
The superior cerebellar peduncle (brachium conjunctivum)
The inferior cerebellar peduncle (——— body)
connects the cerebellum to the ———.
• It receives afferent fibers from the ———, and sends efferents to the —— nuclei.
The inferior cerebellar peduncle (restiform body)
connects the cerebellum to the medulla oblongata.
• It receives afferent fibers from the medulla, and sends efferents to the vestibular nuclei.
Blood supply
Three arteries supply blood to the cerebellum
Blood supply
Three arteries supply blood to the cerebellum
• Superior cerebellar artery (SCA)
• Anterior inferior cerebellar artery (AICA)
• Posterior inferior cerebellar artery (PICA).
Blood supply
• The SCA and AICA branch off the lateral portion of the ——— artery.
• The basilar artery arises from the confluence of the two ——- arteries at the junction between the —— and the ——
• The PICA branches off from the ——- arteries
Blood supply
• The SCA and AICA branch off the lateral portion of the basilar artery.
• The basilar artery arises from the confluence of the two vertebral arteries at the junction between the medulla oblongata and the pons
• The PICA branches off from the vertebral arteries
The vertebral arteries are major arteries of the neck. They branch from the ——— arteries and merge to form the single midline ——— artery
The vertebral arteries are major arteries of the neck. They branch from the subclavian arteries and merge to form the single midline basilar artery
Venous drainage
•Two main veins are responsible for the venous drainage of the cerebellum -which are :
•These veins empty into the ———, ——- and ——— dural venous sinuses.
Venous drainage
•Two main veins are responsible for the venous drainage of the cerebellum -
•Superior cerebellar vein
• Inferior cerebellar vein
•These veins empty into the superior petrosal, transverse and straight dural venous sinuses.
Relations
•Anteriorly:
• Superiorly:
•Anteriorly: fourth ventricle, pons and medulla.
• Superiorly:
cerebral hemisphere and the tentorium cerebelli (a leathery dura mater layer separating the cerebrum from the cerebellum).
•Cerebellar dysfunction can result in a wide variety of manifestations which are:
•Cerebellar dysfunction can result in a wide variety of manifestations that can be summarized using the acronym
DANISH:
• Dysdiadochokinesia
•Ataxia
•Nystagmus
• Intention Tremor
Scanning speech
• Hypotonia
———— - inability to perform smooth rapid alternating movements (e.g: pronation/supination)
Dysdiadochokinesia
•) ———- - inability to perform smooth rapid repetitive movements
• ———- - inability to judge/estimate the range of voluntary movement (passing target points)
•) Dyssynergia- inability to perform smooth rapid repetitive movements
• Dysmetria- inability to judge/estimate the range of voluntary movement (passing target points)
Lesions to the medial part affect —— and ——— musculature
• Results in symptoms such as ——-and ———
Lesions to the medial part affect axial and proximal limb musculature
• Results in symptoms such as truncal ataxia and nystagmus
Lesion in the lateral hemispheres will affect ——- musculature and results in symptoms such as:
• Ipsilateral limb ataxia which manifests as:
Lesion in the lateral hemispheres will affect distal limb musculature and results in symptoms such as:
• Ipsilateral limb ataxia which manifests as:
• Intention tremor
• Dysmetria (Past pointing)
• Dysdiadochokinesis
———— ataxia (due to gradual deterioration of the neurons in the cerebellum)
Freidreich ataxia (due to gradual deterioration of the neurons in the cerebellum)
Bilateral lesions
Bilateral cerebellar lesions can occur as a result of:
Bilateral lesions
Bilateral cerebellar lesions can occur as a result of:
• Demyelination due to multiple sclerosis
• Drugs and toxins such as alcohol and certain drugs like antiepileptic drugs
• Freidreich ataxia (due to gradual deterioration of the neurons in the cerebellum)
• Multiple system’s atrophy
•Bilateral posterior circulation stroke or space-occupying lesions
• Paraneoplastic conditions (such as immune system attacking the cerebellum)
Unilateral Cerebellar Lesion
• Unilateral cerebellar lesions can occur as a result of:
Unilateral Cerebellar Lesion
• Unilateral cerebellar lesions can occur as a result of:
•Space-occupying lesions in the posterior fossa (abscess or tumor)
•Demyelination due to multiple sclerosis
• Posterior circulation
infarction/hemorrhagic stroke
•Paraneoplastic syndrome
