Cerebellum Flashcards
Cerebellum
Underneath the cerebrum and behind the brainstem
Surface layer= Gray matter inner layer (medullar core) = White matter
Cerebellum is considered to be a part of the motor system.
Not the initiator of movement, but the modifier. Think of this as “an error-control device that coordinates all input and output during movement”. Coordination of motor movements and regulation of equilibrium and body posture
Modifies movement related to body position, muscle preparedness, muscle tone, equilibrium, distance, and duration.
Think of the cerebellum as being a “fact checker”, always reviewing motor-information to make sure movements are efficient, smooth and on target; especially fine motor movements
The cerebellum will support different aspects of motor movement that includes:
Muscle synergy:
Muscle tone:
Body equilibrium:
Motor Learning
Remember that the cerebellum does not receive or process sensory information that affects conscious awareness (e.g., “Wow, the ocean is freezing”) or initiate motor movement. But it will help with motor learning and motor memory.
At first, motor movements are effortful, but with practice they become more skilled due to the brain’s ability to reorganize information (remember the brain loves to be efficient) this is essentially motor learning.
“Motor learning begins with a conscious control of movement and gradually ends with the skill acquisition that no longer requires a conscious regulation of the tactile motor activities”.
Efferent Pathways
Pathways that leave the cerebellum (through which peduncles?), can enter the motor cortex, brainstem, thalamus, and spinal cord.
Never forget that many structures of the CNS/PNS are interconnected.
Signs of Cerebellar Dysfunction
Individuals with cerebellar problems cannot preciously control their body parts.
Again, what type of motor movements would this especially affect?
Minor lesions would produce subtle changes with movement, but significant lesions will affect the accuracy and smoothness of movement.
Remember that the cerebellum is just one part of the motor system. However, deficits in the cerebellum (and/or other structures in the CNS/PNS) can cause an array of movement disorders and motor speech disorders.
Be aware that many insults can cause this dysfunction: CVAs, tumors, TBI, Neurodegenerative disease, etc..
Ataxia
Ataxia describes a lack of muscle control or coordination of voluntary movements, such as walking or picking up objects.
A sign of an underlying condition, ataxia can affect various movements, creating difficulties with speech, eye movement and swallowing.
Dysmetria
refers to a lack of coordination of movement typified by the undershoot or overshoot of intended position with the hand, arm, leg, or eye. It is a type of ataxia. It is sometimes described as an inability to judge distance or scale.
Hypotonia
commonly known as floppy baby syndrome, is a state of low muscle tone (the amount of tension or resistance to stretch in a muscle), often involving reduced muscle strength.
Rebounding
elicited by having the patient attempt to move a limb against resistance. When the resistance is suddenly removed, the limb normally moves a short distance in the desired direction and then rebounds (jerks back in the opposite direction)
Disequilibrium
unsteadiness, imbalance, or loss of equilibrium that is often accompanied by spatial disorientation.
Tremors
Tremor is an involuntary, rhythmic muscle contraction leading to shaking movements in one or more parts of the body.
Explain the category of essential tremors?
Action tremor
occurs with the voluntary movement of a muscle. Most types of tremor are considered action tremor. There are several sub-classifications of action tremor, many of which overlap.
Postural tremor occurs when a person maintains a position against gravity, such as holding the arms outstretched.
Kinetic tremor is associated with any voluntary movement, such as moving the wrists up and down or closing and opening the eyes.
Intention tremor is produced with purposeful movement toward a target, such as lifting a finger to touch the nose. Typically the tremor will become worse as an individual gets closer to their target.
Task-specific tremor only appears when performing highly-skilled, goal-oriented tasks such as handwriting or speaking.
Isometric tremor occurs during a voluntary muscle contraction that is not accompanied by any movement such as holding a heavy book or a dumbbell in the same position.
Essential Tremor
For SLPS, our concern will be vocal tremors.
Will hear low pitch and mono-pitch
Intermittent or constant-strangled harshness and pitch breaks
The exact cause of essential tremor is unknown. For some people this tremor is mild and remains stable for many years. The tremor usually appears on both sides of the body, but is often noticed more in the dominant hand because it is an action tremor.
The key feature of essential tremor is a tremor in both hands and arms, which is present during action and when standing still. Additional symptoms may include head tremor (e.g., a “yes” or “no” motion) without abnormal posturing of the head and a shaking or quivering sound to the voice if the tremor affects the voice box. The action tremor in both hands in essential tremor can lead to problems with writing, drawing, drinking from a cup, or using tools or a computer.
Motor Speech Disorders
MSDs are related to neurologic function and neuroanatomy
MSD can be defined as:
Disorders of speech
Resulting from a neurologic impairment
Affecting neuromuscular execution of speech or motor programming of speech
They include the dysarthria and apraxia of speech
Because we are discussing cerebellar deficits and the affects of speech, only dysarthria will be discussed
Dysarthria
problems in oral communication due to paralysis, weakness, abnormal tone, or incoordination of the speech musculature
A family of different speech disorders of muscular strength, speed, and/or coordination of the speech musculature
All dysarthrias are due to one or more lesions with the central and/or peripheral nervous system.
Each dysarthria:
Is distinctive in its sounds (acoustic, perceptual, & muscular characteristics)
Can be determined by the site of lesion or disease of the CNS and PNS
