Movement Control in the Brain and Corticospinal Pathways

Introduction

• Focus on movement control in the brain.
• Importance of cerebral cortex in complex movements (talking, walking, writing).

Primary Motor Cortex

• Located in the precentral gyrus, frontal lobe.
• Connections:
  • Brainstem and spinal cord.
  • Direct connections to motor neurons for dexterity.
• Controls contralateral body parts.
• Important for movement intention and instructions to muscles.

Movement Planning and Coordination

Posterior Parietal Cortex

• Monitors body position relative to environment.
• Larger in humans, aids complex movements.
• Damage: difficulty locating objects, navigating.

Prefrontal Cortex

• Responds to sensory signals guiding movement.
• Predicts outcomes and plans movements.
• Damage: disorganized movements.

Premotor Cortex

• Active before movements.
• Integrates information about target, body's position, and posture.

Supplementary Motor Cortex

• Active post-error.
• Plans, organizes movements, and inhibits inappropriate actions.

Mirror Neurons

• Active during movement preparation and observation.
• Role in understanding, imitating others, and social behavior.

Corticospinal Pathways

• Major efferent pathways for motor cortex messages.
• Comprised of lateral (dorsolateral) and medial (ventromedial) tracts.

Lateral Corticospinal Pathway

• Controls peripheral body movements (arms, hands, feet).
• Crosses in the medulla; contralateral control.
• Originates from primary motor cortex, surrounding areas, and red nucleus.

Medial Corticospinal Pathway

• Controls medial body movements (neck, shoulders, trunk).
• Bilateral control (both sides of the body).
• Originates from primary motor cortex, midbrain's tectum, reticular formation, vestibular nucleus.

Comparison of Pathways

• Lateral Pathway: Peripheral control (hands, feet).
• Medial Pathway: Medial and bilateral control (neck, trunk).

Motor Disorders

• Overview of disorders from damage to spinal cord neurons.
• Examination of pathways and their respective roles in movement control.