Cerebellum

checks the amount, degree, and fluidity of movement that the cerebral cortex gives.

invagination of the meningeal layer of the dura mater that covers and separates the cerebellum from the cerebral cortex.

structure that connects and separates the two lobes of the cerebellum.

- gray matter

- superficial layer

inner layer where you can find subcortical gray matter or nuclei.

- made of layers

• molecular layer

• purkinje layer

• granular layer

- embedded within the white matter

• fastigial nuclei

• globose nuclei

• dentate nuclei

• emboliform nuclei

divisions of the cerebellum.

concerned with equilibrium because of its connection with the vestibular system.

- found in the anterior portion of the cerebellar hemisphere

- concerned with stereotyped movements (recognizes distinction in gait or posture)

- biggest part

- important for coordinated movement

lobes of the cerebellum.

if viewed anteriorly it is v-shaped.

divides the anterior lobe from the rest of the lobes.

- middle lobe

- lies between the primary fissure an the uvulonodular fissure

situated posterior to the uvulonodular lobe.

their primary function is to transmit neurotransmitters.

layers of the cerebellum

- superficial layer

- contains stellate (outer) and basket (inner) cells

- two cells present in the molecular layer

- receives excitatory input and gives it to the other cells of the cerebellum.

- primary output of the cerebellar cortex

- direction of movement: inside to outside

- has dendrites that fans towards the cerebellar cortex/molecular layer (1 way transmission)

- inhibits specific part of the cerebellum

- deepest layer of the cerebellum

- contains parallel fibers

- unmyelinated

- runs perpendicular to the purkinje fibers

- excitatory

receives input from parallel and mossy fibers.

- clusters of nerve cell bodies embedded in the cerebellum

- point of interneuron

- serves as a “stopover” of neurons going in or out of the cerebellum

the largest of the cerebellar nuclei.

is ovoid and is situated medial to the dentate nucleus.

consists of one or more rounded cell groups that lie medial to the emboliform nucleus.

lies near the midline in the vermis close to the roof of the fourth ventricle.

- fibers that don’t go out of the cerebellum but connects with other regions of the cerebellum

- connection of cerebellar hemisphere

- perceives sensory input to the cerebellum

- goes through the inferior and middle cerebellar peduncles

responsible for motor output.

- clusters of small fibers from different parts of the CNS (outside cerebellum) and terminates in the granular cell

- has different origins (e.g. pons, spinal cord, reticular formation, etc.)

- termination: granular cells

responsible for bringing information from olivary nucleus to the purkinje fibers (inferior to superior).

functions:

• coordinating skilled voluntary movements by influencing muscle activity, and controlling equilibrium and muscle tone

• comparator and error correcting mechanism

peduncles of cerebellum.

peduncle connected to the midbrain.

peduncle connected to the pons.

peduncle connected to the medulla oblongata.

cerebellar afferent pathways.

- from the cerebrum to the pontine nuclei - transverse fibers to the contralateral cerebellar

- gives afferent information from the cerebrum to the cerebellum to control the movement

- from the cerebrum to the paired olivary nucleus to the cerebellum

- subserves both (R) and (L) olivary nucleus

- the ipsilateral olivary nucleus has fibers projecting to the contralateral cerebellum

- from the cerebrum to the reticular formation to the cerebellum

- subserves ipsilateral cerebellum

cerebellar efferent pathways

- decussates towards the contralateral red nucleus via the superior cerebellar peduncle

- rubrospinal tract then decussates to the contralteral side. Therefore, GER pathway subserves the ipsilateral side

- decussates on the contalateral VPL thalamus via the superior cerebellar peduncle

- for motor activity

from the fastigial nuclei to the reticular formation via the inferior cerebellar peduncle to form the reticulospinal tract ipsilaterally.

- from fastigial nucleus to the vestibular nucleus of both sides via the inferior cerebellar peduncle

- for vestibulospinal tract; for muscle tone

common cause of cerebellar pathology.

condition that involves the degeneration of the oligodendrocytes.

condition that involves the degeneration of the Schwann cells.

generalized muscle weakness.

loss of ability to associate muscles together for complex movements.

increased time required to initiate voluntary movement.

disorder of motor component of speech.

prolonging of syllable when speaking/ prolonged pausing before speaking.

impaired ability to perform rapid alternating movement.

inability to judge the distance or range of movement.

movement is performed in a sequence of component parts rather than as single smooth action.

- widen base of support

- flexed hips and knee (low center of gravity)

- no arm swinging

- hesitation on swing phase

decrease in muscle tone.

overestimation of distance.

underestimation of distance.

- rapid, involuntary, oscillatory, back and forth movement of the eye

- two reasons:

• cerebellum transfers information to the vestibular nuclei

• cerebellum is responsible for coordination of muscle tone due to extraocular muscle

inability to halt forceful movements.

tremor manifests during movement.

rhythmic oscillation of the head (axial extremity).