Mascle spindle دوک عضلانی عصبی

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Mascle spindle دوک عضلانی عصبی

  1. 1. Presented by Dr Sadatinejad, Seyyed Mohsen,student of Medicine from Iran,Kashan 19/12/2012
  2. 2.  Middle ear muscles : without any MS Muscle Number of MS Latissimus dorsi 400 soleus 400 abductor pollicis brevis 80 quadriceps 1300 medial gastrocnemius 150 extensor digitorum longus (EDL) 190 lumbrical Muscle Density of MS (per gram) lumbrical 12 soleus 0.4 EDL 3.7 Motor units kind of extrafusal muscle fibers : “red” or slow fiber (Type I)
  3. 3. Afferent nerve fiber (Proprioception) Ia: primery ending (annulospiral) end to nuclear bag fibers or Dynamic fiber II : secendary ending (flower-spray) end to nuclear chain fibers or Static fiber
  4. 4. Fig. 8.6. Responses of afferent fibers from a muscle spindle. A,Length of muscle containing muscle spindle. Muscle length ischanged with various waveforms of stretch. B, Response of typeIa afferent fibers from a primary ending of the muscle spindle. C,Response of type II afferent fibers from a secondary ending of themuscle spindle. Type Ia afferents respond to rapid stretch; type IIafferents respond to length.
  5. 5. Efferent Motor fiber (Fusimotor fiber) γ motor neuron:  Dynamic γ moto-neuron innervate nuclear bag fiber sensitivity of Ia fiber  Static γ moto-neuron innervate nuclear chain fiber sensitivity of II fiber
  6. 6. (Negative )Lenght Feedback
  7. 7. Strech Reflex(Myotatic or Tendon Reflex)
  8. 8. Deep Tendon Reflexes• Biceps brachii tendon reflex C5-6 (flexion of the elbow joint by tapping the biceps tendon).• Triceps tendon reflex C6-7 and C8 (extension of the elbow joint by tapping the triceps tendon).• Brachioradialis tendon reflex C5-6 and C7 (supination of the radioulnar joints by tapping the insertion of the brachioradialis tendon).• Patellar tendon reflex (knee jerk) L2, L3, and L4 (extension of knee joint on tapping the patellar tendon).• Achilles tendon reflex (ankle jerk) S1 and 2 (plantar flexion of ankle joint on tapping the Achilles tendon—tendo calcaneus).
  9. 9. Muscle strength reflexes
  10. 10. Monosynaptic arch and Strech Reflex (Ascending & Descending branch)Unconscious Propericeotion Cerebellumconscious Propericeotion Cerebral Cortec and Basal Ganglia
  11. 11. Conscious PropericeotionAfferent Fiber Post horn of 1from Muscle DRGSpindle 1 1 gray matter Medulla oblongata
  12. 12. Conscious PropericeotionAfferent Fiber Post horn of 1from Muscle DRGSpindle 1 1 gray matter Medulla oblongata
  13. 13. Unconscious PropericeotionAfferent Fiber Post horn of 1from Muscle DRGSpindle 1 1 gray matter Medulla oblongata
  14. 14. Sup peduncle Cerebral Corex Basal Ganglia RED NucleusSubsantial Nigra RubroSpinal Tract Ant Horn Of spinal cord γ motor neuron
  15. 15. Sup peduncle Dentothalamic tract Controlateral Ventrolteral (VL) nucleus of Thalamus Internal Capsule (corona radiata) Cerebral Cortex (Primery Motor Area) CorticoSpinal Tract Ant.CorticoSpinal (Pyramidal Fiber) 20% 80%Dicussation in spinal Segment Lat. Cortico Dicussation Of Pyramids Spinal
  16. 16. Inferior C e r e b e l l a r peduncle Reticular Lat.Vestibular Med.Vestibular Formation nucleus nucleusReticulospinal VestibuloSpinal MLF Tract Tract (med.longitudinal Fasiculus) ↑Cranial III,IV,VI ↓Cranial XI to SCM and Trapezious
  17. 17. CorticoTectal tract SpinoTectal Tract Substantial nigraMed & Lat Geniculate RED Nucleus Spinolivary Tract TectoSpinal Dicussation OlivoSpinal Tract Tract in brain Stem (Dicussation in brain Stem) Ant. Horn of Spinal Cord
  18. 18. Common Terminal Moto r Pat hway(A) The common terminal pathway of all centers involve d in moto r activity is the largeanterior horn cell ( A1) and its a xon (!-motoneuron. The central regions that influencemotor activity via descending pathways a re interconnecte d in many ways. The mostimportant af fe rent pathways ste m from the cereb ellum, which receives the impulsesof muscle receptors via the spinocereb ellar tracts (A2) and the stimuli of the cortex viathe corticopontine tracts (A3). The cereb ellar impulses are transmitte d via theparvocellular part of the dentate nucleus ( A4) and the ventral lateral nucleus of thalamus( A5) to the precentral corte x (area 4) (A6). The corticospinal (pyramidal) tract (A7 )descends from area 4 to the anterior horn and gives of f collaterals in the pons ( A8) thatreturn to the cereb ellum. Additional cereb ellar impulses are transmitte d via theemboliform nucleus ( A9 ) and the centromedian nucleus of the thalamus (A10) to thestriatum ( A11) and via the magnocellular part of the dentate nucleus (A12) to the rednucleus (A13). From here f ib ers run in the central tegmental tract (A14) via the olive(A15) back to the cereb ellum and in the rubroreticulospinal tract (A16) to the anteriorhorn. Fib ers from the globose nucleus (A17) run to the interstitial nucleus of Cajal ( A18)and from there i n the interstitiospinal fasciculus (A19) to the anterior horn. Finally, cereb e llofugal f ib ers are relaye d in the ve stibular nuclei (A20) and in the reticularformation (A21 ) to the vestibulospinal tract (A22) and the reticulospinal tract (A23),respectively.The descending pathways can b e divide d into two groups according to theiref fect on the muscles: one group stimulates the fle xor muscles , and another groupstimulates the e xtensor muscles. The corticospinal tract and the rubroret iculospinaltract activate mainly the neurons of the flexor muscles and inhibit the neurons of theextensor muscles. This cor responds to the functional importance of the corticospinaltract for delicate and precise movements, especially those of hand and f inger muscleswhere flexor muscles play an important role. In contrast, the f i b ers of the ve stibulospinal tract and the f i b ers from the pontine reticular formation inhibit the flexorsand activate the ex tensors. They b elong to a p hylogenetically old motor system that isdirecte d against the ef fect of gravity and, thus, is of special importance for body postureand balance. The peripheral f ib ers that run through the posterior ro ot into the anteriorhorn originate from the muscle receptors. The af ferent f i b ers of the annulospiralendings (A24 ) terminate with their collaterals directly on the !-motoneurons, while the fib ers of the tendon organs (A25) terminate o n interneurons. Many descendingpathways influence the !-neurons via the spinal reflex apparatus. They terminate on thelarge !neurons and on the small "-neurons ( A26). Since the "-neurons have a lowerthreshold of stimulation, they a re stimulate d f irst, which results i n the activation ofmuscle spindles. The latter send their impulses to the !-neurons. Thus, the "-neurons andmuscle spindles have a starter function for voluntar y movements.A27 Accessor y olive . A28 Skeletal muscles. A29 Muscle spindle.

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