1. Direct motor pathway Corticospinal pathway

3. Motor Units – Large Versus Small Text Fig. 24-3

4. Spinal cord Reflexes

5. Major receptors involved in spinal cord reflexes: muscle spindle and golgi tendon organ Text Fig. 17-1 Muscle spindle sense change and rate of change in muscle length Golgi tendon organ sense the force of muscle contraction (tension)

6. Muscle stretch reflex

7. Muscle stretch reflex / Reciprocal inhibition

11. Tendon reflex (autogenic inhibition)

12. Flexor (withdrawal ) reflex (nociceptive reflex)

13. Flexor (withdrawal ) reflex (nociceptive reflex)

14. Text Fig. 9-11 Crossed Extension Reflex

15. Text Fig. 9-11 Crossed Extension Reflex

17. Organisation of the motor system Brainstem Extrapyramidal Motor pathways Cerebellum Basal ganglia Supplementary motor cortex Pyramidal tract Premotor cortex Primary motor cortex Visual cortex Somatosensory cortex Motor nuclei of the thalamus Prefrontal cortex

18. Motor system includes Tracts Corticospinal tract (Pyramidal tract ) Extra-pyramidal system Basal Ganglia (regulator) Cerebellum (regulator)

20. Corticospinal pathway

24. Extra-pyramidal System, Basal Ganglia and Cerebellum

25. Extra-pyramidal System Definition: Tracts other than corticospinal tract are known as Extra-pyramidal tract.

28. vestibular apparatus & vestibular nuclei Spinal motor neuron Innervating axial & postural muscles (trunk muscles) Function : maintain Posture & balance “head &eye” and balance reflexes Vestibulospinal tract

29. Red Nucleus in Midbrain Pass down through Pons & Medulla Ends in ant. Horn of spinal cord Control motor neurons Functions. Control Distal muscle of limbs “especially upper limb” Rubrospinal tract

30. Superior & Inferior collicili in midbrain Trunk and head moving muscles Cervical spinal motor neuron of anterior horn Function: Allow turning of the head in response to visual or Auditory stimuli. Tectospinal tract

31. Reticulospinal Tract The reticular formation in the brainstem. It contains many different nuclear groups. Pontine and medullary nuclei projects to the anterior horn of the spinal cord. Functions: is responsible for regulating muscle tone and maintain posture.

32. Motor regulators Motor control systems outside the cortex Basal ganglia - a group of subcortical forebrain nuclei (caudate nucleus, putamen (= striatum), globus palludus, subthalamic nucleus) - modulate patterns of motor activity Cerebellum -controls neural ‘programs’ for the executionl of skilled movements

34. Forebrain Midbrain Input to basal ganglia

35. Output to thalamus and cortex Forebrain Midbrain

36. MOVEMENT DISORDERS  Parkinson disease  Huntingtons disease

37. PARKINSONS DISEASE Effects dopaminergic neurons Neurons are lost from substantia nigra Rarely presents before 50 years Neurodegenerative disease

38. Striatum DopamineGlutamate GABA Neuropathology of Parkinson’s disease nigro-striatal pathway degeneration leading to a depletion of striatal dopamine some degeneration of other dopamine pathways too X

39. CLINICAL FEATURES Characterized by: Tremors Rigidity bradykinesia

40. Huntington’s disease Onset of symptoms usually at 30 to 45 years Genetically determined (single dominant gene) Causes degeneration of the output neurones from the striatum, reducing inhibitory modulation of motor function Progressive disease causing involuntary muscle jerks Striatum DopamineGlutamate GABA X

41. HUNTINGTONS DISEASE Inherited disorder Autosomal dominant Males females equally affected Presents during the 4 th decade Chorea which worsens with time Cognitive disorders Dementia

42. Motor control systems outside the cortex Basal ganglia - a group of subcortical forebrain nuclei (caudate nucleus, putamen (= striatum), globus palludus, subthalamic nucleus) - modulate patterns of motor activity Cerebellum -controls neural ‘programs’ for the executionl of skilled movements

43. GROSS STRUCTURE

44. Organisation of the motor system Brainstem Extrapyramidal Motor pathways Cerebellum Basal ganglia Supplementary motor cortex Pyramidal tract Premotor cortex Primary motor cortex Visual cortex Somatosensory cortex Motor nuclei of the thalamus Prefrontal cortex

45. Feed-back and feedback control circuits

46. Cerebellar connections Input: –Sensory cortex (somato, visual) –Vestibular system –Spinocerebellar tract Output: –Motor cortex –Thalamus motor nuclei –Extra-pyramidal tracts

47. The main functions of cerebellum: body equilibrium regulation of muscle tone coordination of movements

48. A t a x i a means disturbances of equilibrium of the body and coordination of movements. Cerebellum lesion produces cerebellar ataxia

49. Cerebellar ataxia Attactic gait – patient can’t to walk Disorders of equlibrium – patient can’t to stand Intention tremor – is dynamic tremor (it is more expressed while moving and disappears while rest) Nystagmus Dysmetria (disturbed ability to gauge distances)