1 / 69

MOTOR SYSTEMS

MOTOR SYSTEMS. Muscles and Joints Muscles Moving The Spinal Cord Spinal Reflexes Reciprocal Control of Opposing Muscles Polysynaptic Adaptations and Reflexes The Motor Cortex The Basal Ganglia Limbic System The Cerebellum Cranial Nerves.

perdy
Télécharger la présentation

MOTOR SYSTEMS

An Image/Link below is provided (as is) to download presentation Download Policy: Content on the Website is provided to you AS IS for your information and personal use and may not be sold / licensed / shared on other websites without getting consent from its author. Content is provided to you AS IS for your information and personal use only. Download presentation by click this link. While downloading, if for some reason you are not able to download a presentation, the publisher may have deleted the file from their server. During download, if you can't get a presentation, the file might be deleted by the publisher.

E N D

Presentation Transcript

  1. MOTOR SYSTEMS • Muscles and Joints • Muscles • Moving • The Spinal Cord • Spinal Reflexes • Reciprocal Control of Opposing Muscles • Polysynaptic Adaptations and Reflexes • The Motor Cortex • The Basal Ganglia • Limbic System • The Cerebellum • Cranial Nerves

  2. Muscle groups are complex; attach bone to bone via tendons and ligaments

  3. A muscle group has many fibers

  4. The Neuromuscular junction (NMJ): The receptive portion of muscle-the motor end-plate

  5. The NMJ ( sometimes called the motor end-plate)

  6. nACHr

  7. End-plate potential • Larger • Longer • Leads to Ca+ influx in sarcolema of muscle • Ca+ causes muscle contraction

  8. Disease of the NMJ? MG

  9. MG

  10. muscle fibers encase myofibrils. The casing is called the sarcolema Muscle group myofibril Muscle fiber

  11. End-plate potential causes ca+ influx into sarcolemma

  12. Myofibrils in turn contain “Actin and Myosin” filaments

  13. When the NMJ is activated Actin-myosin interact to shorten the length of a muscle fiber

  14. Sliding filament model of muscular contraction

  15. Muscle shortens=work

  16. Goal-directed Complex Higher levels of control Plastic Numerous reflexive behaviors are involved Reflexive Simple Automatic inplastic Cortical vs Spinal control of behavior

  17. Spinal reflex ARCs • Monosynaptic • stretch • Polysynaptic • Withdrawal • Antagonist muscle groups • Synergistic muscle groups • Polysegmental relexes • Cross-spinal reflexes

  18. A “monosynaptic” spinal reflex arc- the Stretch reflex

  19. The stretch reflex involves neuromuscular “spindles”

  20. Stretch reflex regulates muscle tension in every muscle group

  21. The polysynaptic part of stretch reflexes: inhibition of Antagonist muscles

  22. Spinal inhibition of antagonist muscles require inhibitory interneurons

  23. The “withdrawal reflex arc” a polysynaptic spinal reflex

  24. Also involves interneurons

  25. And may involve more than one spinal cord segment

  26. And/or Cross spinal reflex arcs

  27. The Goli tendon organ (GTO) reflex

  28. Neural activity of spinal neurons related to whole muscle group activity

  29. Lower motor neurons “the final common pathway”

  30. Goal-Directed Behavior and Reflexive Behavior

  31. Goal-Directed Behaviors Require: • Goal selection and prioritization • Resistance to distracters -Cross-modal Sensory integration • Perception of target • Awareness of location of movable body part • Ability to aim movement of body part • Ability to detect errors and re-adjust, (use feedback) • Ability to use feedback to control movement of body part

  32. Sensory-Motor Integration in the frontal lobes

  33. THE DLPFC: “The conductor” Integrates cross modal input- may initiate goal-directed behaviors Lesions of the dorsolateral frontal areas results in a number of “executive” motor impairments. These include perseveration, incoordination, motor impersistence, apraxias and hypokinesia.

  34. The premotor and supplementary motor ctx: “The sections” Stimulation= complex sequences of behavior (aimless behavior)

  35. Damage to the secondary Motor Cortex? • Ideomotor Apraxia • This apraxia is associated with great difficulty in the sequencing and execution of movements. A common test of apraxia is to request the patient to demonstrate the use of a tool or household implement (e.g., "Show me how to cut with scissors"). Difficulties are apparent when the patient moves the hand randomly in space or uses the hand as the object itself, such as using the forefinger and middle finger as blades of the scissors. They have additional trouble sequencing the correct series of movements and make errors in orienting their limbs in space consistent with the desired action. Imitation of the movements of others will usually improve performance but it is still usually defective. • Memories for skilled acts are probably stored in the angular gyrus of the parietal lobe in the left hemisphere.

  36. The primary motor cortex; “the instrument” Stimulation = relatively simple fragments of behavior

  37. TWO MAJOR DESCENDING PATHWAYS FROM THE PRIMARY MOTOR CORTEX: The Dorsolateral pathway

  38. And the VM Path. • The VM pathway does not discretely decussate, but does branch and innervate contra lateral segments in the spinal cord.

  39. Dorsolateral Decussates at medullary pyramids Distal muscle groups More direct More volitional control Higher resolution of control Ventromedial Does not cross Medial muscle groups Gives off spinal collaterals Yoking Lower resolution of control DL vs VM descending motor paths

  40. Other Motor Pathways • In addition there are other motor paths that have relays in the brainstem • These other paths innervate nuclei of the RAS, cranial nerve nuclei, etc…

  41. Descending paths get additional inputs

  42. Both pathways terminate in spinal cord segments

  43. According to part of the body they control

  44. On lower motor neurons (alpha motor neurons)

More Related