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106 Cards in this Set
- Front
- Back
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what's a A stereotypic reaction evoked in response to a stimulus?
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reflex
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do we have lots of reflexes?
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Many somatic and autonomic functions mediated by cord are reflex in nature
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why are reflexes imp?
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Valuable clinical tool for assessing integrity of both afferent and efferent part of a reflex circuit
General level of excitability of the spinal cord |
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what's a monosynaptic reflex?
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2 neurons (afferent & efferent)
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what's a polysynaptic reflex?
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Polysynaptic reflex: reflex center consists of 1 or more interneurons
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is this:
e.g., flexor withdrawal, cross extensor an ex of monosynaptic or polysynaptic reflex? |
polysynaptic
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is this:
Stretch (myotatic) reflex: e.g., patellar an ex of monosynaptic or polysynaptic reflex? |
monosynaptic
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Stretch (Myotatic) Reflex Mediated by _________________
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Ia Spindle Afferent
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when you stretch a muscle, get contraction of ____________
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same (homonymous) muscle in which muscle spindle resides
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describe a muscle stretch?
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Reflex contraction of muscle and its synergist (observed action)
Relaxation of antagonist muscle (not observed) |
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single Ia afferent synapses on all LMNs innerv __________ in reflex contraction of muscle and its synergist
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homonymous muscle (100s LMNs)
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glycinergic inhib neuron where spindle afferent Ia stims feedforward inhibition that leads to inhib OF _____________
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LMN that goes to antagonist muscle
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what's a good ex of reciprocal inhibition?
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relaxation of antagonist muscle
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what's the stimulus for the patellar reflex?
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tap knee
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what do you cause when you tap knee?
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Stretch quadriceps muscle
Ia afferent phasic discharge |
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what's the reflex of tapping the knee?
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knee extension
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what happens during the knee tap reflex?
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Reflex contraction of homonymous & synergist: MONSYNAPTIC
Relaxation of antagonist (reciprocal inhibition): POLYSYNAPTIC |
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when does Ia afferent phasic discharge happen?
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stimulus of tapping knee
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when does Reflex contraction of homonymous & synergist: MONSYNAPTIC happen?
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reflex extension of knee
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when does Relaxation of antagonist (reciprocal inhibition): POLYSYNAPTIC happen?
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reflex extension of knee
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what is Reflex contraction of homonymous & synergist: mono or polysynaptic?
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monosynaptic
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what is Relaxation of antagonist (reciprocal inhibition): mono or polysynaptic?
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polysynaptic
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what's the observed reflex act: mono or polysynaptic?
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monosynaptic
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what's the unobserved relaxation: mono or polysynaptic?
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polysynaptic
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what are the common types of stretch (monosynaptic) reflexes tested in neuro exam?
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biceps reflex
brachioradial reflex triceps reflex quadriceps (patellar) reflex triceps surae (achilles) reflex |
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which reflex is at C7-8 level?
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triceps reflex
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which reflex is at C5-6 level?
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biceps reflex
brachioradialis reflex |
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which reflex is at S1 level?
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triceps surae (achilles) reflex
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which reflex is at L3-4 level?
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quadriceps (patellar) reflex
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which reflex test extension of elbow thru tap on triceps tendon?
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triceps reflex
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which reflex test shows extension of knee by tapping ligamentum patellae?
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quadriceps (patellar) reflex
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which reflex test shows plantar flexion of foot by tapping Achilles tendon?
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triceps surae (achilles) reflex
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which reflex test shows flexion of elbow by tapping styloid process of radius?
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brachioradial reflex
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which reflex test shows flexion of elbow and supination of forearm by tapping biceps tendon?
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biceps reflex
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how do stretch reflexes related to muscle tone?
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Stretch reflexes underlie muscle tone
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are stretch reflexes in all muscles?
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found in some degree in all muscles
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which muscle groups are stretch reflexes found more prominently?
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anti-gravity muscles
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which reflexes test radial n?
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brachioradialis
triceps : triceps brachii |
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which reflexes test musculocutaneous n?
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biceps : biceps brachii!
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which reflexes test tibial n?
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ankle jerk (Achilles) :
gastrocnemius, soleus |
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which reflexes test femoral n?
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knee jerk (patellar): quadriceps femoris
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the inverse myotatic reflex is mediated by?
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Ib (GTO) afferent
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what does GTO monitor?
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muscle tension
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GTO afferents exert effects readily observed in _________________
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extensor muscles
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GTO afferents exert effects more widespread in _____________________
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SpC than more restricted action of MS afferents
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GTO-Ib afferent system is a ___________________
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tension-feedback system
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High/low -threshold for GTO activation?
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HIGH-threshold for GTO activation
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when you have Muscle fatigue: decreased muscle tension results in ______________
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increased tension!
*less inhibition, so more tension |
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the flexor (Withdrawal) Reflex & Cross-Extensor Reflex is mediated by?
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small diameter afferents
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if touch something electrical, how does body react?
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moves hand and extends limbs for postural control
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what's the benefit of small diameter afferent reflexes?
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These reflexes produce responses that serve to protect or escape
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which flexors and extensors are involved in Flexor (Withdrawal) Reflex & Cross-Extensor Reflex?
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ipsilateral flexors
contralateral extensors |
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which types of afferents are involved in Flexor (Withdrawal) Reflex & Cross-Extensor Reflex?
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III and IV afferents
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where do III and IV afferents come from for Flexor (Withdrawal) Reflex & Cross-Extensor Reflex?
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deep receptors in muscle or cutaneous receptors
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afferents in Flexor (Withdrawal) Reflex & Cross-Extensor Reflex carry info about :
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painful or noxious stimuli
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what's the name of the tract ass w/ flexor withdrawal reflex: stepping on tack?
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Lissauer's tract
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what happens in flexor withdrawal reflex?
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Flexion at knee to avoid painful stimuli
Mediated by multiple spinal levels |
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how do you assess muscle Tone due to Stretch Reflex?
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elicited in passive limb manipulation
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Muscle tone is manifestation of _______________
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normal reflex
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describe what happens in stretch reflex:
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Sensory input elicited by stretch
Resistance due to reflex contraction |
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what's decreased muscle tone- decreased resistance ?
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hypotonia
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what's increased tone- increased resistance?
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hypertonia
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what's flaccid limb? (stiff limb)?
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flaccid- hypotonia
stiff- hypertonia |
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what type of increased resistance is seen in hypertonia?
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clasp-knife
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what's overactive (“brisk”) stretch reflexes?
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hyperreflexia
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what are sustained rhythmic contraction evoked by sudden maintained stretch (differs from fasciculation?
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clonus
*activated by low-threshold stretch reflex |
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spastic muscle is typical of what type of lesion?
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UMN lesion
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what does : clasp-knife, hyperreflexia, clonus and spasticity, rigidity describe?
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hypertonia!!!!!!!!!!!!!!!
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what does Cog–wheel type of increased resistance (lead-pipe rigidity in PD) describe?
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rigidity
*not often associated w/ changes in stretch reflexes |
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what do Supraspinal & Intraspinal Influences on Reflex Activity say about spinal cord and descending pathways?
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Spinal cord contains basic circuitry to generate spinal reflexes
Descending pathways modulate local spinal circuits |
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what happens Immediately after spinal transection (acute condition)?
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areflexia
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what does areflexia result in?
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Loss of all reflexes (incl. sphincteric reflexes)
Flaccid paralysis below lesion; decreased sympathetic tone (vasc. sm) |
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over time, spinal shock disappears and what develops in flexor muscles?
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hyperreflexia
*UMN signs; some sphincteric/erectile reflexes w/o voluntary control |
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what do you see in Transmitter receptors after spinal shock?
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supersensitivity
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what happens to descending (-) influences after spinal shock?
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Removal of descending (-) influences from supraspinal levels
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do any nerves grow after spinal shock?
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Collateral Sprouting!
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what effect does Removal of descending (-) influences from supraspinal levels?
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Reflex arc disinhibited- hyperactive stretch reflexes
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Spinal cats are transected at ______________
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lower thoracic levels
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Spinal cats are transected at lower thoracic levels, but Spinal cat is still able to automatically ___________________
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step with its hindlimbs
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what's the effect when spinal cat?
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Removing descending influences or control of hindlimbs
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Spinal cat is still able to automatically step with its hindlimbs
b/c : |
Sensory feedback in hindlimb from moving treadmill triggers intrinsic spinal-cord circuits for rhythmic locomotor activity
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where are the Pattern generators for locomotion?
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in spinal cord
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what does muscle weakness indicate a deficit in?
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strength
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how does muscle weakness present in LMN paralysis?
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affects individual muscles
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how does muscle weakness present in UMN paralysis?
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affects groups of muscles
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how does atrophy present in LMN paralysis?
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pronounces LMN paralysis
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what does atrophy indicate?
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bulk loss
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how does atrophy present in UMN paralysis?
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slight UMN paralysis, due to disuse
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how does resistance to passive resistance present in LMN paralysis?
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hypotonia
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how does resistance to passive resistance present in UMN paralysis?
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spasticity
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how do tendon reflexes present in LMN paralysis?
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depressed or lost
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how do tendon reflexes present in UMN paralysis?
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increased
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how do plantar reflexes present in LMN paralysis?
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flexor
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how do plantar reflexes present in UMN paralysis?
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extensor (Babinski sign)
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how do fasciculations present in LMN paralysis?
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present: contracting
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how do fasciculations present in UMN paralysis?
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absent or clonus
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if denervated muscle at neuromuscular junc, will you have trophic factors communicating b/w nerve and muscle?
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no! and muscle will atrophy
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if stroke in pyramids, CST won't work and will affect:
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grps of muscles
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what's a normal response when testing testing plantar response?
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plantar flexion
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what's a abnormal response when testing testing plantar response?
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Babinski sign: dorsiflexion of big toe
*CST damage! IF IN NEWBORN: no big deal, CST not fully myelinated |
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what do you see in UMN increased muscle tone?
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brisk reflexes
inc muscle tone muscle stiffness (spasticity) weakness |
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what do you see in clonus UMR?
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keeps twitching as long as muscle stretched
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what do you see in LMN hyporeflexia?
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absent reflexes
*decreased MSRs |
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what do you see in Babinski UMN:
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extension of big toe
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what's seen in LMN: fasciculations.. ALS?
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muscle twitches/spasms --> sustained.. no stretching leads to spasms
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when can you see LMN atrophy?
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diabetes mellitus
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