reflexes, clasifications, and functions.

1. REFLEX CONTENTS: DEFINITION REFLEX ARC TYPES/CLASSIFICATION OF REFLEXES STRETCH REFLEX MUSCLE SPINDLE PROPERTIES OF REFLEXES 10-Feb-14 1 Dr. Ashok Solanki

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4. Nerve pathways Ascending Tracts Tract Signal function Dorsal columns Vibration, tactile sensation, conscious proprioception Spinocerebeller Proprioception Spinothalamic (lateral and anterior) Pain, temperature, itch (lateral), crude touch (anterior) Spinoreticular Pain Spinomesencephalic Pain Spino-cervico-thalamic Pain (touch?) Spinohypothalamic Pain

5. Structure of spinal cord 10-Feb-14 Dr. Ashok Solanki 5

6. Fetal 3 rd month: ends at coccyx Birth: ends at L3 Adult position at approx L1-2 during childhood End: conus medullaris This tapers into filum terminale of connective tissue, tethered to coccyx Spinal cord segments are superior to where their corresponding spinal nerves emerge through intervetebral foramina (see also fig 17.5, p 288) Denticulate ligaments : lateral shelves of pia mater anchoring to dura (meninges: more later) Spinal cord http://www.apparelyzed.com/spinalcord.html

7. Spinal nerves continued Divided based on vertebral locations 8 cervical 12 thoracic 5 lumbar 5 sacral 1 coccygeal Cauda equina (“horse’s tail”): collection of nerve roots at inferior end of vertebral canal

8. Classified as According to centre IN THE SPINAL CORD- seg , inter, supra. According to function- flexor, extensor, postural R. Clinically- supreficial , deep, visceral No. of synapse involved. Mono and polysynaptic According to origin– spinal cord, brain stem, cortical etc. Conditional and unconditional – since birth Rapid, stereotyped, invountary response to a sensory stimuli consciouslly or unconsciouslly . 8 10-Feb-14 Dr. Ashok Solanki

9. CLASSIFICATION CONDITIONED (ACQUIRED)/ UNCONDITIONED(SINCE BIRTH) CEREBELLER, CORTICAL, MIDBRAIN, SPINAL SOMATIC:FLEXOR , EXTENSOR VISCERAL: AUTONOMIC MONOSYNAPTIC , POLYSYNAPTIC SUPERFICIAL, DEEP, VISCERAL, PATHOLOGICAL SEGMENTAL, INTERSEGMENTAL, SUPRASEGMENTAL 10-Feb-14 9 Dr. Ashok Solanki

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12. Functions or reflex action Maintain the homeostasis- b.p regulation, heart rate, digestive , autonomic reflexes Automatic actions Balance and posture Reflex maintining the movements -eyes 12 10-Feb-14 Dr. Ashok Solanki

13. REFLEX ARC ANATOMICAL NERVOUS PATHWAY OF REFLEX IS CALLED REFLEX ARC. RECEPTOR SENSORY / AFFERENT NERVE CENTER EFFERENT / MOTOR NERVE EFFECTOR ORGAN * BELL-MAGENDIE LAW: DORSAL ROOTS ARE SENSORY & VENTRAL ROOTS ARE MOTOR. 10-Feb-14 13 Dr. Ashok Solanki

14. SUPERFICIAL REFLEXES CORNEAL AND CONJUNCTIVAL REFLEX PHARYNGEAL REFLEX PALATAL REFLEX ABDOMINAL RELEX PLANTAR REFLEX: Scratch over the outer edge of sole cause plantar flexion and adduction of all toes and dorsiflexion and inversion of foot.( L5,S1) ANAL REFLEX 10-Feb-14 14 Dr. Ashok Solanki

15. DEEP REFLEXES JAW JERK: 5 TH CRANIAL NV NUCLEI BICEPS JERK: C5,6 TRICEPS JERK: C6,7 SUPINATOR JERK: C5,6 KNEE JERK: L2,3,4 ANKLE JERK: S1,2 10-Feb-14 15 Dr. Ashok Solanki

16. Reflex Arc Specific nerve impulse pathway 5 components of reflex arc receptor sensory neuron integrating center motor neuron effector Dr. Ashok Solanki 16 10-Feb-14

17. PROPERTIES ONE WAY CONDUCTION SUMMATION: SPATIAL, TEMPORAL OCCLUSION SUBLIMINAL FRINGE RECRUITMENT AFTERDISCHARGE REBOUND PHENOMENON FATIGUE RECIPROCAL INNERVATION AND RECIPROCAL INHIBITION 10-Feb-14 17 Dr. Ashok Solanki

18. Flexor (withdrawal) Reflex Step on tack (pain fibers send signal to spinal cord Interneurons branch to different spinal cord segments Motor fibers in several segments are activated More than one muscle group activated to lift foot off of tack Dr. Ashok Solanki 18 10-Feb-14

19. Crossed Extensor Reflex Lifting left foot requires extension of right leg to maintain one’s balance Pain signals cross to opposite spinal cord Contralateral extensor muscles are stimulated by interneurons to hold up the body weight Reciprocal innervation - when extensors contract flexors relax, etc Dr. Ashok Solanki 19 10-Feb-14

20. Clinical Considerations Checking a patient’s reflexes may help to detect disorders/injury Plantar flexion reflex -- stroke the lateral margin of the sole normal response is curling under the toes abnormal response or response of children under 18 months is called Babinski sign (upward fanning of toes due to incomplete myelination in child) Dr. Ashok Solanki 20 10-Feb-14

21. Inverse stretch reflex Golgi tendon organ- 2 to 15 in each muscle. Responds to tension and not the length The Golgi tendon reflex is a protective reflex rise in tension is sensed by the Golgi tendon a which stimulates the I-b stimulates the I-b afferents stimulate the inhibitory interneurons inhibit the α- motoneuron discharge to the muscle This reflex relaxation of the extrafusal muscle fibers 21 10-Feb-14 Dr. Ashok Solanki

22. INVERSE STRETCH REFLEX/ AUTOGENIC INHIBITION WHEN A MUSCLE IS STRETCHED, IT CONTRACTS BUT IF THE STRETCH IS MAINTAINED (CONTINUED), THE MUSCLE RELAXES. 10-Feb-14 22 Dr. Ashok Solanki

23. UMN lesions weakness, paralysis spasticity tendon reflexes + Babinski sign little,if any,muscle atrophy no fasiculation LMN lesions weakness, paralysis flaccidity, hypotonia Hypo- /no tendon reflex - Babinski sign muscle atrophy fasiculation of involved muscle 10-Feb-14 23 Dr. Ashok Solanki

24. VISCERAL REFLEXES PUPILLARY REFLEXES : DIRECT LIGHT REFLEX INDIRECT OR CONSENSUAL LIGHT REFLEX ACCOMODATION REFLEX : CONSTRICTION OF PUPIL, CONVERGENCE OF EYE BALLS, INCREASE IN ANTERIOR CURVATURE OF LENS CILIOSPINAL REFLEX : STIMULATION OF SKIN IN NECK –DILATATION OF PUPILS OCULOCARDIAC REFLEX : PRESSURE OVER EYEBALLS - BRADYCARDIA 10-Feb-14 24 Dr. Ashok Solanki

25. PATHOLOGICAL REFLEXES BABINSKI’S SIGN + Dorsiflexion of great toe and fanning of other toes. CLONUS PENDULAR MOVEMENTS 10-Feb-14 25 Dr. Ashok Solanki

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29. Flexor reflex (Withdrawal, "hot stove") 1. receptors sense pain 2. sensory impulse to spinal cord 3. synapse to association neuron, synapse to motor neurons polysynaptic 4. motor neurons to flexor muscles to 5. withdraw offended body part from stimulus 10-Feb-14 Dr. Ashok Solanki 29

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31. Spinal reflexes Static stretch reflex- maintain the tone Maintain constant degree of muscle contraction (Tone) Continuous static receptor signal → transmitted via both primary and secondary neurons → S.C → continuous command by static gamma motor neurons → Tone. Normal tone is due to continuous dischrge of gamma m. n. 10-Feb-14 31 Dr. Ashok Solanki

32. Stretch reflex 2 types -Response that is transmitted: Dynemic : -when there is change in the length of the spindle receptor (stretching of the sensory receptor area of the muscle spindle by stretching of the muscle spindle or the whole muscle). Detect Change in length. -transmitted by the primary fiber A α type Static continuous information about the length of the muscle (not the change in length). transmitted by both the primary A α and secondary (A β and A γ ) 10-Feb-14 32 Dr. Ashok Solanki

33. APPLIED : Decreased (hypoactive) stretch reflex: Destruction of sensory or motor nerve to the muscle Stimulation of inhibitory areas in brain Inhibition of facilitatory areas in the brain Hypothyroidism 10-Feb-14 33 Dr. Ashok Solanki

34. Importance or use of stretch reflex : 1. Tone maintenance 2. Maintenance of posture 3. Control of voluntary movements 10-Feb-14 34 Dr. Ashok Solanki

35. What are the components of reflex action? Components of reflex forms reflex arc involving 1. receptor- sensory organ 2. afferent neuron- 3. centre 4. efferent neuron 5. effector organ 35 10-Feb-14 Dr. Ashok Solanki

36. Reflex arc Diagram showing complete reflex arc 36 10-Feb-14 Dr. Ashok Solanki

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39. 2. 5 Essential Components of the Reflex Arc 39 Dr. Ashok Solanki Stimulus at distal end of neuron Skin Spinal cord (in cross section) Interneuron Receptor Effector Sensory neuron Motor neuron Integration center (a) 10-Feb-14 Dr. Ashok Solanki

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