Motor Systems and Movement Production

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Questions and Answers

What are the three main types of movement?

Voluntary muscle actions, unconscious movements, fine motor skills

Static movements, dynamic movements, rhythmic movements

Involuntary movements, reflex responses, cognitive actions

Reflex responses, voluntary movements, rhythmic motor patterns (correct)

Which of the following best describes the function of the pyramidal tracts?

Regulate emotional responses

Control conscious/voluntary movements (correct)

Manage balance and posture

Control involuntary movements

What muscles do the corticobulbar tract control?

Muscles in the head, face and neck (correct)

Eyes and tongue

Limbs and trunk

Core muscles

Where are the cell bodies of the upper motor neurons of the pyramidal tracts primarily located?

Motor cortex Signup and view all the answers

Which tract primarily controls voluntary muscles?

Corticospinal tract Signup and view all the answers

Which of the following is NOT a function of the frontal lobe?

Breathing control Signup and view all the answers

Which descending pathway is involved in controlling unconscious movements?

Extrapyramidal pathway Signup and view all the answers

What are the two tracts involved in voluntary movements?

Corticobulbar and corticospinal tracts Signup and view all the answers

What type of neurons are Betz and non-Betz cells, and where are they primarily located?

Upper motor neurons located in layer 5 of the primary motor cortex Signup and view all the answers

Which statement accurately describes the role of the premotor cortex?

It plays a key role in the spatial planning of movement and understanding others' actions. Signup and view all the answers

What function is primarily associated with the supplementary motor area (SMA)?

Stabilizing body posture and coordinating movements of both sides of the body Signup and view all the answers

Which of the following brain regions does the motor cortex send axons to, directly or indirectly?

Basal ganglia, cerebellum, and thalamus Signup and view all the answers

What aspect of motor function do Betz and non-Betz cells primarily influence?

Control of voluntary movements Signup and view all the answers

Why is feedback from the basal ganglia and cerebellum important for the motor cortex?

It allows for correction and refinement of the planned movements. Signup and view all the answers

The primary function of the motor cortex is to:

Control movement and motor functions. Signup and view all the answers

Which area is located anterior to the primary motor cortex and is involved in movement planning?

Premotor cortex Signup and view all the answers

What does the somatic motor system primarily control?

Voluntary contraction of skeletal muscles Signup and view all the answers

Which type of muscle is controlled by the autonomic motor system?

Smooth muscle and cardiac muscle Signup and view all the answers

What is the function of cardiac pacemaker cells?

To initiate and maintain the heartbeat Signup and view all the answers

How does the autonomic motor system differentiate neurotransmitters?

According to the sympathetic or parasympathetic nature Signup and view all the answers

Which of the following statements is true regarding the diaphragm?

It is classified as a skeletal muscle and has both voluntary and involuntary control. Signup and view all the answers

What is a key similarity between the somatic and autonomic motor systems?

Both contain cholinergic motor neurons that extend axons out of the spinal cord or brainstem. Signup and view all the answers

Which muscle types are involved in the esophagus's control?

Both smooth and striated muscle Signup and view all the answers

How do the autonomic and somatic systems control their target tissues?

The somatic system directly innervates target tissues, while the autonomic system uses post-ganglionic neurons. Signup and view all the answers

What regions of the brain does the motor cortex send axons to in order to control movement?

Basal ganglia, cerebellum, thalamus, and brainstem nuclei Signup and view all the answers

Which voluntary movements are specifically controlled by the corticobulbar tracts?

Movements of the head, neck, face, mouth, and tongue Signup and view all the answers

Where are the lower motor neurons associated with the corticobulbar tract located?

Brainstem motor nuclei Signup and view all the answers

How do the corticospinal tracts decussate and what types are formed?

They decussate at the pyramids of the medulla, forming lateral and anterior CSTs Signup and view all the answers

Which of the following cranial nerves does NOT have a somatic motor component?

VIII (vestibulocochlear) Signup and view all the answers

What is the role of the axons sent by the motor cortex to other brain regions?

To compare planned movements with actual movements Signup and view all the answers

What white matter areas do the corticospinal tracts travel through as they descend?

Internal capsule, corona radiata, and cerebral peduncles Signup and view all the answers

How does the corticobulbar tract connect to the lower motor neurons?

With synapses on lower motor neurons in brainstem motor nuclei Signup and view all the answers

What role does the prefrontal cortex play in motor control?

It is involved in the coordination, goal setting, and execution of motor actions. Signup and view all the answers

How does the posterior parietal cortex contribute to motor output?

It transforms multisensory information into motor commands. Signup and view all the answers

What is the primary function of the somatosensory cortex in relation to motor control?

To receive sensory inputs and assist in planning and feedback for movements. Signup and view all the answers

What role does the cerebellum play in motor control?

It contributes to coordination, precision, and timing of movements. Signup and view all the answers

Which function is NOT associated with the basal ganglia?

Integration of sensory information for movement. Signup and view all the answers

How does the thalamus contribute to motor systems?

It serves as a relay station for feedback to the motor cortex. Signup and view all the answers

Which area provides sensory information that is crucial for guiding movements?

Posterior parietal cortex. Signup and view all the answers

What function does the prefrontal cortex NOT directly perform?

Providing sensory inputs for motor planning. Signup and view all the answers

Study Notes

Motor Systems

Somatic Motor System: Controls voluntary and involuntary contraction of skeletal muscle.
Autonomic Motor System: Controls involuntary contraction of smooth muscles, cardiac muscles, and gland secretions.
Diaphragm: A skeletal muscle under voluntary and involuntary control for breathing.
Esophagus: Contains both smooth and striated muscle, controlled by both the autonomic and somatic nervous systems.

Movement Production

Movement is produced by contraction and relaxation of skeletal muscles.
Three Types of Movement:
- Reflex Responses: Automatic responses like breathing, coughing, knee jerk, and withdrawal.
- Voluntary Movements: Consciously controlled movements like playing an instrument, peeling fruit, and typing.
- Rhythmic Motor Patterns: Repetitive movements like walking, running, and chewing.

Descending Motor Systems

Pyramidal/Direct System: Controls conscious/voluntary movements through the corticobulbar and corticospinal tracts.
Extrapyramidal/Indirect System: Controls unconscious/involuntary movement through three tracts and the rubrospinal tract for voluntary muscle control.

Pyramidal Tracts

Corticobulbar Tract: Controls muscles of the head, face, and neck.
Corticospinal Tract: Controls muscles below the neck, including limbs and trunk.
Origin: Both tracts originate in the motor cortex (primarily primary motor cortex, but also premotor cortex and supplementary motor area).

Motor Cortex Function

Controls voluntary movements.
Provides input to involuntary movements.
Receives input from:
- Prefrontal Cortex
- Somatosensory Cortex
- Posterior Parietal Cortex
- Thalamus (indirect input from basal ganglia and cerebellum)

Betz and Non-Betz Cells

Upper motor neurons in layer 5 of the primary motor cortex, but likely present in other motor regions as well.
Premotor Cortex: Located anterior to the primary motor cortex; plays a role in planning movement, spatial guidance, and understanding actions.
Supplementary Motor Area (SMA): Located anterior to the primary motor cortex and dorsal to the premotor cortex; involved in posture stabilization, coordination of both sides of the body, and controlling movement sequences.

Motor Cortex Output

The motor cortex sends axons to:
- Basal Ganglia
- Cerebellum (via the corticopontine tract)
- Thalamus (corticothalamic tract)
- Brainstem nuclei in the extrapyramidal tracts
Function: Controls movement, potentially by sending a copy of planned movements for feedback and coordination.

Motor Input to Motor Cortex

Prefrontal Cortex: Role in goal setting, decision-making, motivation, and cognitive control, providing some direct connections to the premotor cortex.
Posterior Parietal Cortex (PPC): Plays a role in planning, sensory guidance, and motor commands.
Somatosensory Cortex (Area 3a): May be functionally part of motor control circuitry, with direct connections to the motor cortex for sensory input.
Cerebellum: Contributes to coordination, precision, and timing of movements.
Basal Ganglia: Involved in the control, selection, and initiation of voluntary movements, procedural learning, and motivation.
Thalamus: Relay station for information, including motor commands and feedback from the cerebellum.

Corticobulbar Tract

Controls voluntary movements of the head, neck, face, mouth, and tongue.
Upper motor neurons synapse on lower motor neurons and local circuit neurons in brainstem motor nuclei of cranial nerves III, IV, V, VI, VII, IX, X, XI, and XII.

Corticospinal Tract

Travels through the corona radiata, internal capsule, and midbrain cerebral peduncles.
Splits at the pyramids of the medulla.
Lateral Corticospinal Tract: About 85-90% of axons cross over at the pyramids.
Anterior Corticospinal Tract: About 10-15% of axons do not cross over.
Both tracts descend separately in the spinal cord.

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Description

Explore the intricacies of the motor systems in the human body, including the somatic and autonomic motor systems. This quiz covers how movement is produced and the types of movements such as reflex responses, voluntary movements, and rhythmic motor patterns. Test your knowledge on the roles of various muscles involved in movement.