1. MOTOR SYSTEM Dr. Zahoor Ali Shaikh

2. TRANSVERS SECTION OF SPINAL CORD

3. MOTOR UNIT

4. Types of motor neuron α – motor neuron γ - motor neuron

5. Types of muscle fibers Extrafusal muscle fibers ( cause muscle contraction supplied by α - motor neuron) Intrafusal muscle fibers or muscle spindle (receptor for stretch reflex, supplied by γ - motor neuron)

6. MUSCLE SPINDLE (INTRAFUSAL FIBERS)

7. MUSCLE EXTRAFUSAL FIBERS MUSCLE INTRAFUSAL FIBERS

8. Muscle spindle Nuclear bag fiber Nuclear chain fiber Sensory innervations of muscle spindle Ia – nuclear bag & nuclear chain fibers II – nuclear chain fibers Motor supply – γ motor neuron Dynamic & Static

9. Reflex Definition Components of reflex arc  Receptor  Afferent pathway  Center  Efferent pathway  Effector organ

10. Components of reflex arc

11. Classification of reflexes Monosynaptic or stretch reflex or tendon jerk eg. Bicep jerk tricep jerk, supinator jerk knee jerk, ankle jerk Polysynaptic reflex eg. Withdrawal reflex Abdominal reflex Plantar reflex Visceral reflex eg. Micturation, defecation reflex Jendressik Phenomenon

12. KNEE JERK – MONOSYNAPTIC REFLEX

15. POLYSYNAPTIC REFLEX

16. WITDRAWEL REFLEX - POLYSYNAPTIC REFLEX

17. DIFFERENT REFLEXES SHOWN

22. Motor cortex corticospinal (pyramidal tract) Upper motor neuron (pyramidal & extrapyramidal tracts) Lower motor neuron Difference between upper & lower motor neuron lesion (UMNL & LMNL)

26. MOTOR TRACTS

28. DIFFERENCE BETWEEN UPPER & LOWER MOTOR NEURON LESION UMN LESION Paralysis affect movement rather than muscles Muscle wasting is only from disuse, therefore slight. Occasionally marked in chronic severe lesions. Spasticity of clasp- knife’ type. Muscles hypertonic. LMN LESION Individual muscle or group of muscles are affected. Wasting pronounced. Flaccidity. Muscles hypotonic.

29. Tendon reflexes increased. Clonus often present. Superficial reflexes diminished or modified. Abdominal reflex absent. Babinski’s sign +ve, Increased jaw jerk. Tendon reflexes diminished or absent. Superficial reflexes often unaltered.