Spinal Cord Control Systems: Exploring Movement Patterns

1. Change of location for class as of Monday Jan. 23 Odette Building room 112

2. Central Pattern Generators • Local circuits in the spinal cord • Can control complex timing and coordination of complex movement patterns. • In cats, timing of movements is accomplished at the spinal cord level, but not support.

4. Central Pattern Generators • Each limb has its own cpg • Cpg’s are connected by local circuits • Cpg’s in humans, may have more regulatory input from upper motor neuron pathways.

5. Lamprey cpg’s • Spinal cord innervates muscle segments • Identified mns in stereotyped positions • Intrinsic firing pattern • Know know nt’s, firing patterns, regulation of all components • Reciprocal inhibition across the spinal cord cause alternate sides to contract.

6. Ch. 16 Upper Motor Neuron Control • Posture: vestibular nuclei & reticular formation --> terminal zones in medial spinal cord. • Precise movements of distal parts of limbs: motor cortex --> terminal fields in the lateral parts of the spinal cord gray matter in a few spinal cord segments

7. Upper motor neuron • Gives rise to a descending projection that controls the activity of lower motor neurons in the brain stem and the spinal cord.

10. Brainstem structures • Influence of lower motor neurons to neck muscles: superior colliculus axons project to medial cell groups in the cervical cord. These generate head orienting movements.

11. Red nucleus axons: together with lateral corticospinal tract axons • --> control arms.

12. Brainstem • Upper motor neurons for balance and posture • Vestibular nuclei are upper motor neurons with descending axons that terminate in the medial region of the spinal cord gray matter. • Information from cranial nerve VIII (inner ear)

13. Pathways through vestibular nuclei • Cranial nerve VIII --> vestibular nuclei --> descending axons --> Lateral vestibular tract: most terminate in medial region of spinal cord. OR Medial vestibular tract: some extend laterally to contact muscles.

14. Pathways through vestibular nuclei • Also, pathways from upper motor neurons to lower motor neurons that control eye movements.

15. Reticular Formation • Network of circuits • Located at the brainstem core, from midbrain to medulla. • Descending motor control pathways to the spinal cord - terminate primarily in the medial parts of the gray matter where they influence the local circuit neurons that co-ordinate axial and proximal limb muscles.

16. Reticular formation: functions • cardiovascular & respiratory control. • sensory motor reflexes • org. of eye movements • regulate sleep and wakefullness • * temporal and spatial co-ordination of movement

17. Posture • In response to disturbances in body position (env or self) • -->Vestibular nuclei and reticular formation • --> information to the spinal cord

18. Vestibular nuclei • response from inner ear to change in balance • Inner ear • Vestibular nuclei • Direct projections to the spinal cord • Compensation in stability

19. Adjustments to stabilize posture during ongoing movements • Motor centers in cortex or brain stem • reticular formation • Appropriate neurons are activated

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