Higher Motor Centres (HMC)

Question 1

Where is the motor cortex located?

Answer 1

The motor cortex is located in the rear portion of the frontal lobe, just before the central sulcus, which separates the frontal lobe from the parietal lobe.

Question 2

What is the primary role of the motor cortex?

Answer 2

The motor cortex is primarily involved in controlling voluntary movements and is one of the brain areas most crucial for goal-directed movement.

Question 3

What types of information must the motor cortex receive to carry out goal-directed movements?

Answer 3

The motor cortex receives information about:

1. Body’s position in space (from the parietal lobe)
2. The goal to be attained and the strategy to achieve it (from the anterior portion of the frontal lobe)
3. Memories of past strategies (from the temporal lobe)

Question 4

What are the key responsibilities of the motor cortex?

Answer 4

1. Releases command sequences for locomotor activities.
2. Key higher motor centre in learning new motor activities through visual observation (“see and reproduce”) or imagination (“think and invent”).
3. Primary HMC for voluntary (intentional) movement.
4. Primary HMC for dexterity and fine motor control.
5. Key HMC for functions combining cognitive and fine motor functions, such as speech.
6. Plays a larger role in complex, skillful, and bilateral movements.
7. Contributes to baseline motor system tone due to its constant output.

Question 5

What are the symptoms of dysfunction in the motor cortex?

Answer 5

• Most Impaired:
1. Ability to learn new motor skills.
2. Motor functions that rely on fine motor control.
3. Speech.
4. Voluntary activity (from thought to initiation).

• Lesser Degree of Impairment:
1. Generalized hypotonia (reduced tone in the motor system).
2. Weaker/slower recruitment of power.
3. Performance issues with complex, large-scale skillful movements.

Question 6

What is generalized hypotonia?

Answer 6

Generalized hypotonia refers to a reduced tone in the motor system, leading to lower resting tone and weaker/slower recruitment of muscle power.

Question 7

Where is the cerebellum located?

Answer 7

The cerebellum is located at the base of the posterior brain.

Question 8

What is the structure of the cerebellum?

Answer 8

The cerebellum is composed of a number of lobes and lobules. These convolutions increase the surface area of the cerebellar cortex and provide a very high density of neurons.

Question 9

How much of the brain’s total volume does the cerebellum account for, and how many neurons does it contain?

Answer 9

The cerebellum accounts for about 10% of the brain’s total volume but contains over 50% of its neurons.

Question 10

What is the role of the cerebellum in movement control?

Answer 10

The cerebellum receives information about the intended movement from the sensory and motor cortexes and sends information back to the motor cortex about the required direction, force, and duration of the movement.

Question 11

What does the cerebellum’s motor loop operate alongside?

Answer 11

The cerebellum’s motor loop operates alongside a loop involving the basal ganglia to regulate the details of motor control.

Question 12

What are the key responsibilities of the cerebellum?

Answer 12

1. Coordination and integration of elements within movement command packages.
2. Monitoring incoming sensory information (especially visual and proprioceptive data) and integrating it for effective movements.
3. Regulating the body’s motor adjustments to the horizon and gravity.
4. Sequencing and ordering of commands, crucial for rapid, complex actions (SSS: Speed, Sequencing, Synchronicity).
5. Aiding in the learning of new or improved motor activities and mobilizing motor commands into memory.
6. Constant fine-tuning of motor commands by monitoring motor cortex output and making adjustments.
7. Suppression of tremor during purposeful body part activity by counteracting surge-like motor cortex output.

Question 13

What does the cerebellum do to fine-tune motor commands?

Answer 13

The cerebellum constantly fine-tunes motor commands by monitoring motor cortex output and making adjustments both during and after the commands are issued.

Question 14

How does the cerebellum help with tremor suppression?

Answer 14

The cerebellum suppresses tremor during purposeful body part activity by counteracting the surge-like qualities of motor cortex output.

Question 15

What is Dyssynergia/Asynergia?

Answer 15

Generalized incoordination; loss of smooth coordination in movements.

Question 16

What is Intention Tremor?

Answer 16

A tremor that occurs during purposeful activity; the tremor initiates or intensifies as the activity progresses.

Question 17

What is Dysmetria?

Answer 17

Failure to pinpoint a target accurately; also known as pass-pointing, it is the inability to bring a body part to the target along an efficient path.

Question 18

What is Nystagmus?

Answer 18

A combination of intention tremor and dysmetria pertaining to the eyes; when attempting to focus on a visual target, the eyes rapidly “shimmy” back and forth, usually horizontally.

Question 19

What is Dysdiadochokinesia?

Answer 19

Impaired ability to perform rapidly alternating movements, especially those requiring a mirrored pattern with matching limbs.

Question 20

What is Decomposition of Movement?

Answer 20

A person breaks the motor activity into component parts, performing them one at a time, often requiring more effort and focus than normal.

Question 21

What is Scanning Speech?

Answer 21

Decomposition of speech; the person breaks words or phrases into syllables and speaks them slowly and deliberately, often in a monotonous tone without normal inflection or punctuation breaks.

Question 22

What is Impairment of Motor Memory?

Answer 22

Difficulty recalling or repeating previously learned motor activities.

Question 23

What is Vertigo?

Answer 23

Hallucination of movement, either of the person’s body or of the external environment, or both.

Question 24

What are Disorders of Balance & Equilibrium?

Answer 24

Impaired ability to maintain the center of gravity in static positions and during movement.

Question 25

What is Dystaxia/Ataxia?

Answer 25

Also known as the “drunken sailor’s gait”, a person walks with a “lurching” or “staggering” gait, typically with a wider stance. It includes various cerebellar impairments: poor body coordination, poor equilibrium, difficulty sensing the ground or objects in the environment (leading to frequent bumping or falls), and may involve hallucinations of moving ground or objects, as well as intention tremors in the legs.

Question 26

What are the Basal Ganglia?

Answer 26

The basal ganglia are a set of neural structures located deep inside the cerebrum. These clusters of nerve cells are tightly interconnected and receive information from different regions of the cerebral cortex. After processing the information, they return it to the motor cortex via the thalamus.

Question 27

What is the responsibility of the Basal Ganglia in the motor system?

Answer 27

1. First Initiator: Scans for incoming data and alerts other centers to issue new command sequences.
2. Oversight of Reflexive Relationships: Manages agonist/antagonist/synergist relationships, postural reflexes (e.g., righting reflexes), and background positioning of the trunk and limb girdles.
3. Error Correction: Monitors incoming motor system data and suppresses incorrect automatic responses.
4. Emotion Expression: Plays a major role in the motor aspects of emotional expression, particularly reflexive/involuntary facial expressions.
5. Motor Memory: Involved in creating and regulating stereotyped, reflexive components of repeated activities/skills.
6. Gracefulness and Efficiency: Adds fluidity and efficiency to movement.
7. Suppression of Tremor: Counteracts surge-like qualities of motor cortex output to suppress tremor in body parts not engaged in purposeful activity.

Question 28

What is Resting Tremor in the context of Basal Ganglia dysfunction?

Answer 28

A tremor that occurs when the body part is not engaged in purposeful activity, typically observed at rest.

Question 29

What is Hypokinesia?

Answer 29

A condition where movement is slow and effortful, often due to dysfunction in the Basal Ganglia.

Question 30

What is the difference between Bradykinesia and Akinesia?

Answer 30

• Bradykinesia: Slow movement initiation, including difficulty starting, changing course, adding new components, modulating speed, or stopping movements.
• Akinesia: Inability to initiate movement altogether.

Question 31

What are the impairments of efficiency and gracefulness associated with Basal Ganglia dysfunction?

Answer 31

Routine activities become slow, clumsy, and exhausting to perform. Movements lack smoothness and fluidity, and the person may appear awkward in their actions.

Question 32

What is the impaired physical expression of emotion seen in Basal Ganglia dysfunction?

Answer 32

The person’s body and facial expressions do not reflect their emotional state, often resulting in a “mask” appearance (e.g., in Parkinsonism), with an expression of indifference or negativity.

Question 33

What are Disorders of Postural Control?

Answer 33

Disorders of postural control include:

1. Postural Tremor: Tremors that begin when a body part is held in a position for a short period of time.
2. Absence or Impairment of Postural Reflexes: Such as righting reflex and walking-related reflexes (e.g., festination).
3. Improper Stabilization of Limb Girdles or Spine: Failures of synergistic stabilization leading to limb girdle collapse or truncal collapse during motor activities.

Question 34

What is Rigidity in relation to postural control?

Answer 34

Rigidity is the impaired reciprocal inhibition, where the agonist/antagonist relationship fails and both muscles contract simultaneously (concentric contraction).

Question 35

What are the two types of Rigidity seen in the limbs?

Answer 35

• Lead Pipe Rigidity: Consistent resistance to movement throughout the range of motion.
• Cogwheel Rigidity: Resistance to movement that has a stop/start pattern, feeling like a “ratchet” movement.

Question 36

What is Parkinsonian Mask (Mask of Parkinsonism)?

Answer 36

Facial Rigidity where the person does not make automatically responsive facial expressions. This can make it difficult to interpret the patient’s emotional state or discomfort during treatment.

Question 37

What should an RMT be aware of regarding facial expressions in patients with rigidity?

Answer 37

RMTs may not be able to rely on facial expressions to indicate discomfort during treatment. Verbal communication should be used to assess the patient’s response to treatment.

Question 38

What are the respiratory impairments associated with rigidity?

Answer 38

1. Apical Breathing: Breathing primarily from the chest, rather than the diaphragm.
2. Dyspnea: Shortness of breath, especially with exertion or in specific positions.
3. Poor Mucociliary Elevator Function: Increased risk of respiratory infections due to poor mucus clearance.

Question 39

What are the gastrointestinal impairments seen with rigidity?

Answer 39

1. Dysphagia: Difficulty swallowing.
2. Aphagia: Inability to swallow.
   RMT Alert: There is a choking or aspiration risk when the person is in a supine position.
3. Constipation: Atonic constipation due to impaired peristalsis and poor recruitment of reflexive components.

Question 40

What is Festination (also known as Festinating Gait)?

Answer 40

Festination is a shuffling gait where the person has difficulty starting to walk and often throws their upper body forward to create momentum.

• The gait starts slowly but picks up speed, and the person cannot change course, slow down, or stop effectively (may include episodes of freezing).
• The gait lacks arm swing, knee lift, and toe-off reflexes, resulting in a straight-kneed, flat-footed appearance.
• Movement is effortful and clunky, and there may be a postural tremor.
• The person fatigues easily.

Question 41

What are the characteristics of Involuntary Movements?

Answer 41

Involuntary movements are the result of poor inhibition of automatic/reflexive movements. These movements can vary and include the following types:

1. Tic
2. Athetosis
3. Chorea
4. Ballism
5. Dystonia
6. Dyskinesia

Question 42

What is a Tic?

Answer 42

A Tic is a sudden sharp contraction, typically in the face or other body parts, sometimes affecting the whole body.

• Tics often occur singly but can happen in a series.

Question 43

What is Athetosis?

Answer 43

Athetosis refers to writhing, snake-like, or worm-like movements, usually occurring bilaterally at the wrists, ankles, or whole legs.

Question 44

What is Chorea?

Answer 44

Chorea is a movement disorder characterized by a dance-like sequence of movements that travel along the affected body part(s) in a consistent pattern.

Question 45

What is Ballism?

Answer 45

Ballism is a large-scale, explosive sudden movement of a body part(s), often occurring suddenly and violently.

Question 46

What is Dystonia?

Answer 46

Dystonia is a condition where a body part migrates into an extreme position and freezes there for a period of time.

Question 47

What is Dyskinesia?

Answer 47

Dyskinesia is a type of movement where a body part(s) enacts a circular or cyclical swaying movement, usually repeated in a continuous loop.