Successfully reported this slideshow.

Motor functions

9

Share

Upcoming SlideShare
Motor system overview 2011
Motor system overview 2011
Loading in …3
×
1 of 36
1 of 36

More Related Content

Related Books

Free with a 14 day trial from Scribd

See all

Related Audiobooks

Free with a 14 day trial from Scribd

See all

Motor functions

  1. 1. MOTOR FUNCTIONS PRESETED BY SRILOY MOHANTY B.N.Y.S
  2. 2. MOTOR CORTEX • Primary motor cortex ( M1) • Premotor area (PMA) • Supplementary motor area (SMA) Note: All the three projects directly to the spinal cord via corticospinal tract. • Premotor and supplementary motor cortex also project to primary motor cortex and is involved in coordinating & planning complex sequences of movement (motor learning).
  3. 3. PRIMARY MOTOR CORTEX (M-I) Location :- Immediately anterior to the central sulcus and extends to the medial surface of hemisphere also known as Broadmann’s area 4 is a motor homunculus. Description: Body is represented as up side down and stretched on the medial surface where pelvic and leg muscles are represented. Hand and mouth has a greater area of
  4. 4. - It controls the musculature of the opposite side of the body. -Face area is bilaterally represented. Functions:- Is used in execution of skilled movements also in codes the direction, force and velocity of movements. Lesions:- Pure M-I lesions are rare. May have contra lateral weakness in distal muscle (fingers). Ability to control fine movements is gone. Ablation of M-I alone cause hypotonia not Spasticity.
  5. 5. SUPPLEMENTARY MOTOR AREA (M-II) Location: Found on both in lateral and medial aspect of the frontal lobe. It extends from cingulate sulcus on the medial side to reach premotor cortex on the lateral surface of the brain. Function: It works together with premotor cortex. Involved in programming of motor sequences. Lesions: Produces awkwardness in performing complex activity like bimanual coordinated activity.
  6. 6. It function in mental rehearsal of movements before performing a complex motor functions. With premotor cortex it translates the desire to perform a motor task into a series of motor command that will do the task.
  7. 7. PREMOTOR CORTEX (PMC) Location: Broadmann’s area 6. It lies immediately anterior to primary motor cortex. It is more extensive than primary motor cortex (about 6 times) Functions: It works with the help of basal ganglia, thalamus, primary motor cortex, posterior parietal cortex. It plays role in planning and anticipation of a specific motor act.
  8. 8. Premotor cortex – Two-hand Coordination THE MONKEY HAS LEARNED THE TASK PUSH THE OBJECT THROUGH THE HOLE AND CATCH IT WITH THE OTHER HAND; With damage to premotor cortex, cannot coordinate two hands to do the task
  9. 9. Lesion: It results in re-emergence of suckling and grasp reflex in adults. Its lesion do not case paralysis but only slowing of the complex limb movement. Lesion may result in loss of short-term or working memory. When damaged with supplementary cortex it may result in APRAXIA.
  10. 10. VOLUNTARY MOVEMENT: INSTRUCTIONS FROM CEREBRAL CORTEX • Dorsolateral Prefrontal Cortex: directs movement of our limbs (as in reaching) and movements of our fingers. • Actual signal for movement must go through pre-motor cortex, then motor cortex. • From motor cortex, signal travels down spinal cord eventually reaching the alpha motor neuron. • BUT, the instructions for this movement ultimately comes from our Parietal lobe, which receives sensory input.
  11. 11. CEREBELLUM • Vermis • Intermediate zone • Lateral zone • Within are deep cerebellar nuclei: • Fastigial nucleus • Interpositus nucleus • Dentate nucleus
  12. 12. VERMIS Kinesthetic and somatosensory inputs from the spinal cord projections to fastigial nucleus • Damage interrupts posture and walking • In monkeys, unilateral lesions of the fastigial nucleus cause the monkeys to fall (ipsilateral side)
  13. 13. INTERMEDIATE ZONE • Inputs from red nucleus (brain stem & motor cortex) and somatosensory info from the spinal cord • Projects to interpositus nucleus  red nucleus (loop) • Damage produces rigidity and difficulty in moving limbs • Action tremor or intention tremor – a tremor causing movement to occur in a staggered manner during motor act.
  14. 14. LATERAL ZONE • Inputs from motor and association cortices (through pons) • Projections to dentate nucleus  primary motor and premotor cortex 1. Balistic movement – movement that occurs so quickly that it can not be modified by feedback • E.g., swinging of a batter trying to hit a ball moving 140 km/h
  15. 15. LATERAL ZONE 2. Multijoint movements 3. Learning of new movements 4. Timing of motor movements (and cognitive functions)
  16. 16. BASAL GANGLIA • Unlike the cerebellum, which plays a role in rapid balistic movements, the basal ganglia are more important for the accomplishment of movements that may take some time to initiate or stop • Important for internal guiding (rather then external) of movement • Dopamine – nigrostriatal pathway
  17. 17. BASAL GANGLIA Damage to the basal ganglia: • Produces either too much activation (hyperkinetic) responses= twitches, movements bursts, jarring, etc. • Huntington’s Chorea-dominant gene based, increases glutamate in striatum which destroys GABA neurons in BG and loss of inhibition • No cure • Tourette’s OR • Produces too little force (hypokinetic)=rigidity • Parkinson’s disease Pink=inhibition Blue=excitation
  18. 18. BRAIN STEM MOTOR CENTERS • Pontine reticular nuclei – excite antigravity muscles (muscles of the vertebral column and limb extensor muscles) – pontine reticulospinal tract. • Medullary reticular nuclei – inhibit antigravity muscles – medullary reticulospinal tract. Pontine & medullary systems balance each other. • Vestibular nuclei – supplement the excitatory function of the pontine system by integrating vestibular information – lateral and medial vestibulospinal tracts.
  19. 19. Summary of the major descending spinal tracts and their points of origin corticospinal tract rubrospinal tract reticulospinal tracts tectospinal, vestibulospinal tracts
  20. 20. Corticospinal Tract Origin – Sensory cortex, primary Motor Cortex, premotor & supplementary cortex (40%) (30%) (30%) Internal Capsule Cerebral Peduncle (midbarain) Pons Medullary Pyramid Pyramidal Decussation Lat.Cross & Vent. Uncross White matter in spinal cord Ant. Horn of spinal cord through a interconnection α motor neuron of opposite side
  21. 21. MOTOR UNIT…
  22. 22. •Every striated muscle has encapsulated muscle fibers scattered throughout the muscle called muscle spindles. •Extrafusal and intrafusal fibers
  23. 23. organization of motor subsystems
  24. 24. Overview - organization of motor systems Motor Cortex Brain Stem Spinal Cord Skeletal muscle -motor neuron Final common pathway
  25. 25. Steps in Motor Action
  26. 26. THANK YOU…

×