Lecture by Dr. Mike on how the brain controls motor movement
Focus on spinal cord anatomy and motor information pathways
Spinal Cord Structure
Gray Matter: Deep inside the spinal cord where neurons communicate and integrate information
White Matter: Pathways or tracts that carry electrical signals
Sensory information: Ascends to the brain
Motor information: Descends from the brain
Motor Information Pathways
Types of Signals
Pyramidal Signals: Direct signals to specific muscles for conscious movement
Extrapyramidal Signals: Indirect pathways for unconscious movement and fine-tuning conscious movements
Pyramidal System
Corticospinal Tracts: Highways for conscious movement, originating from the motor cortex
Lateral Corticospinal Tract:
Originates from the motor cortex in the precentral gyrus of the frontal lobe
Controls fine motor movements of limbs
Crosses at the medulla (decussation)
Descends via the lateral corticospinal tract to the appropriate spinal segment
Ventral (Anterior) Corticospinal Tract:
Controls movement of the trunk
Descends down the same side of the brain and crosses at the spinal level it innervates
Stops at the mid-thoracic area
Extrapyramidal Tracts
Rubrospinal Tract:
Plays a role similar to the lateral corticospinal tract
Affects fine motor movement of limbs
Disappears by the cervical region of the spinal cord
Lesions affect flexion and gripping abilities
Reticulospinal and Vestibulospinal Tracts:
Responsible for posture, balance, and coordinated movement
Involves input from the vestibular system (balance, head movement, position)
Tectospinal Tract:
Involved in head and eye movement
Reflexive response to visual or auditory cues
Summary
This overview covers how motor information descends from the brain through various pathways, each with specific roles in controlling different types of movement and posture.