MOTOR SYSTEMS:POSTURE AND LOCOMOTION

1. MOTOR SYSTEMS:POSTURE AND LOCOMOTION D. C. MIKULECKY PROFESSOR OF PHYSIOLOGY AND FACULTY MENTORING PROGRAM

2. CONTROL OF POSTURE BY THE BRAIN STEM • THE VENTROMEDIAL PATHWAY • THE LATERAL RETICULOSPINAL TRACT • THE RUBROSPINAL TRACTH

3. BRAIN STEM CENTERS FOR MOTOR CONTROL TECTUM LATERAL RETICULAR FORMATION RED NUCLEUS MEDIAL RETICULAR FORMATION LATERAL AND MEDIAL VESTIBULAR NUCLEI

4. THE VENTROMEDIAL PATHWAY • VESTIBULOSPINAL TRACT: CARRIES INFORMATION FROM VESTIBULAR NUCLEUS FOR REFLEX CONTROL OF EQUILIBRIUM • TECTOSPINAL TRACT: ORIGINATES IN TECTUM FOR CONTROL OF HEAD AND EYE MOVEMENTS • MEDIAL RETICULOSPINAL TRACT: ORIGINATES IN RETICULAR FORMATION FOR MAINTAINING POSTURE BY ACTIVATION OF EXTENSORS

5. PATHWAYS FROM BRAINSTEM FOR MOTOR CONTROL: VENTROMEDIAL TECTO- SPINAL TRACT VESTIBULO- SPINAL TRACTS RETICULO- SPINAL TRACT

6. LOCATION OF CELL BODIES FOR EXTENSORS AND FLEXORS FLEXORS EXTENSORS

7. THE LATERAL RETICULOSPINAL TRACT • FROM LATERAL RETICULAR NUCLEUS • DESCEND IN LATERAL REGION OF THE SPINAL CORD

8. PATHWAYS FROM BRAINSTEM FOR MOTOR CONTROL:LATERAL RETICULOSPINAL TRACT LATERAL RETICULO- SPINAL TRACT

9. THE RUBROSPINAL TRACTH • FIBERS ORIGINATE IN RED NUCLEUS • DESCEND ALONG DORSAL AND LATERAL BORDERS OF CORD • INNERVATE DISTAL FLEXOR MUSCLES

10. PATHWAYS FROM BRAINSTEM FOR MOTOR CONTROL: RUBROSPINAL

11. SUMMARY OF CONTROL OF SPINAL MOTOR NEURONS BY BRAIN STEM RUBRO- SPINAL TRACT LATERAL RETICULO- SPINAL TRACT (-) (-) (+) (-) (+) TO FLEXORS TO FLEXORS TO EXTENSORS VENTROMEDIAL PATHWAY TO EXTENSORS

12. THE MOTOR CORTEX • ORGANIZATION • DESCENDING PATHWAYS • SENSORY FEEDBACK • CORTICAL CODING OF REACHING MOVEMENTS

13. ORGANIZATION OF THE MOTOR CORTEX • CORTICAL EFFERENT ZONES: VERTICAL COLUMNS OF CELLS • EACH ZONE CONTROLS ONE MUSCLE • SIX DIFFERENT LAYERS OF CELLS • OUTPUT LAYER IS LAYER V • EXCITE BOTH ALPHA AND GAMMA MOTOR NEURONS

14. CORTICAL AREAS INVOVED IN MOTOR CONTROL

16. SOMATOTOPIC ORGANIZATION OF THE MOTOR CORTEX

17. DESCENDING PATHWAYS FROM THE MOTOR CORTEX • CORTICOSPINAL PATHWAY • CORTICOBULBAR PATHWAY • PYRAMIDAL TRACT • LATERAL CORTICOSPINAL TRACT

18. PATHWAYS FROM CORTEX FOR MOTOR CONTROL: LATERAL CORTICOSPINAL TRACT PREMOTOR AREA LATERAL CORTICO- SPINAL TRACT DORSAL COLUMN NUCLEI RED NUCLEUS 1 2 3 4 6 PRIMARY MOTOR CORTEX PYRAMIDAL TRACT

19. PATHWAYS FROM CORTEX FOR MOTOR CONTROL: CORTICOSPINAL TRACTS PREMOTOR AREA LATERAL CORTICO- SPINAL TRACT DORSAL COLUMN NUCLEI RED NUCLEUS 1 2 3 4 6 VENTRAL CORTICO- SPINAL TRACT PRIMARY MOTOR CORTEX PYRAMIDAL TRACT

20. SENSORY FEEDBACK TO THE MOTOR CORTEX • VIA SOMATIC SENSORY CORTEX • CONNECTED IN A TOPOGRAPHIC MANNER • MONITOR MOVEMENT AND SMOOTH AND CORRECT

21. CORTICAL CODING OF REACHING MOVEMENTS • DYNAMIC NEURONS CODE FOR RATE OF FORCE DEVELOPMENT • STEADY STATE FORCE • NEURONS CONTROLLING RATE AND DIRECTION OF MOVEMENT ARE DISTRIBUTED (NO ONE NEURON HAS ALL THE INFORMATION)

22. SUPPLIMENTAL MOTOR AREAS PROGRAM MOVEMENT • HYPOTHALAMUS INVOLVED IN MOTIVATIONAL FACTORS • TRANSMIT INFORMATION TO SUPPLIMENTAL AND PREMOTOR CORTEX • HERE THE DESIGN OF THE MOVEMENT IS EXECUTED • REHERSAL OF MOVEMENTS AS WELL

23. POSTERIOR PARIETAL CORTEX INTEGRATES SENSORY STIMULI FOR PURPOSEFUL MOVEMENT • RECEIVES BOTH SOMATIC AND VISUAL SENSORY INFORMATION • TRANSMITS IT TO SUPPLIMENTAL AND PREMOTOR AREAS

24. CORTICAL AREAS INVOVED IN MOTOR CONTROL

25. THE CEREBELLUM AND BASAL GANGLIA COORDINATE MOVEMENTS • THE CEREBELLUM IS INVOLVED IN PLANNING, COORDINATION, AND POSTURE • ANTERIOR AND POSTERIOR LOBES INVOLVED IN LIMB MOVEMENT • FLOCCULONODULAR LOBE IS INVOLVED IN EQUILIBRIUM AND POSTURE

27. FUNCTIONS OF THE CEREBELLUM • PLANNING OF A MOVEMENT • CONTROL OF POSTURE AND EQUILIBRIUM • CONTROL OF SMOOTH LIMB MOVEMENT

28. CELL TYPES AND CIRCUITS IN THE CEREBELLUM

29. PURKINJE CELLS ARE THE MOST PROMINENT OF ALL THE CEREBELLAR CELL TYPES • TWO INPUTS: CLIMBING FIBERS (FROM OLIVARY NUCLEUS) AND PARALLEL FIBERS FROM GRANULE CELLS • OUTPUT VARIES ACORDING TO INPUT: CLIMING FIBERS LEAD TO COMPLEX PATTERNS WHILE PARALLEL FIBERS GENERATE SIMPLE PATTERNS

30. THE BASAL GANGLIA

31. THE BASAL GANGLIA PLAN MOVEMENTS • PRIMARY INPUT FROM NEOCORTEX • OTHER INPUTS FROM THE THALAMUS AND SUBSTANTIA NIGRA • GLOBUS PALLIDUS PROVIDES OUTPUT • COGNITIVE FUNCTIONS

32. BASAL GANGLIA: AFFERENT CONNECTIONS CORTEX CAUDATE THALAMUS PUTAMEN SUBSTANTIA NIGRA

33. BASAL GANGLIA: INTRINSIC CONNECTIONS CORTEX CAUDATE THALAMUS PUTAMEN GLOBUS PALLIDUS SUBSTANTIA NIGRA

34. BASAL GANGLIA: EFFERENT CONNECTIONS CAUDATE THALAMUS PUTAMEN GLOBUS PALLIDUS SUBSTANTIA NIGRA

35. BASAL GANGLIA OUTPUT TO CORTEX VIA THALAMUS • MODULATE DESCENDING COMPONENTS OF THE MOTOR SYSTEM • ADDITIONAL OUTPUTS TO SUBSTANTIA NIGRA USE DOPAMINE AS NEUROTRANSMITTER: THESE DEGENERATE IN PARKINSON’S DISEASE

36. THE VESTIBULAR APPARATUS • SEMICIRCULAR CANALS: HAIR CELLS SENSE MOTION • THREE COORDINATE PLANES: SUPERIOR, INFERIOR, AND HORIZONTAL • UTRICLE AND SACCULE DETECT LINEAR ACCELERATION IN HORIZONTAL AND VERTICLE PLANES

37. DISEASES OF THE MOTOR SYSTEM • UPPER-MOTOR-NEURON LESIONS • CORTICOSPINAL TRACT LESIONS • LOWER MOTOR NEURON LESIONS • CEREBELLAR LESIONS

38. UPPER-MOTOR-NEURON LESIONS • PARALYSIS ON SIDE OF BODY OPPOSITE LESION • INCREASED MUSCLE TONE • EXTENSION OF BIG TOE AND BABINSKI SIGN • LACK OF MUSCLE ATROPHY

39. CORTICOSPINAL TRACT LESIONS • LOSS OF STRENGTH AND MOVEMENT OF MUSCLE GROUPS • LOSS OF STRENGTH IN VOLUNTARY MUSCLE CONTRACTION • BABINSKI SIGN

40. LOWER MOTOR NEURON LESIONS • IPSOLATERAL HYPOACTIVE REFLEXES • PARALYSIS • FLACID MUSCLES WITH PROMINENT ATROPHY

41. CEREBELLAR LESIONS • IPSILATERAL DISTURBANCES • LATERAL LESIONS RESULT IN COORDINATION LOSS • LESIONS IN THE VERMIS PRODUCE ATAXIA (LOSS OF COORDINATION) • FLOCCULONODULAR LOBE LESIONS PRODUCE EQUILIBRIUM DISTURBANCE AND ATAXIA