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137 Cards in this Set
- Front
- Back
- 3rd side (hint)
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What are Spinal Reflexes (SR)?
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Spinal reflexes describe a library of simple postural and movement programs used by an organism.
- They are automatic stereotyped reactions. |
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Spinal Reflexes are responses to what?
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adequate stimulation, without conscious, voluntary actions.
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What is Adequate stimulation ?
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It is the form of energy to which a receptor is most sensitive.
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What is a reflex arc?
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The complete nervous path that is involved in a reflex
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What are the 2 types of reflex arcs?
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1. Monosynaptic reflex
2. Polysynaptic reflex |
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Differentiate between the 2 types of reflex arcs?
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1. Monosynaptic reflex is the simplest reflex arc, and it consists of a single central synapse between the afferent fiber and the motoneuron
2. Polysynaptic reflex has one or more interneurons between the afferent fiber and the motoneuron. The majority of the spinal reflexes are polysynaptic in nature. |
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What is an example of a monosynaptic reflex?
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stretch or myotatic reflex
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1. Any type of receptor structure sends information to where?
2. What should you consider when naming a reflex arc ? |
1. the CNS
2. only the number of synapses in the CNS (ignore synapses at the effector organ) |
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Whay may happen to Collaterals from afferent fibers involved in polysynaptic reflexes ?
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They may spread up and down several segments of the spinal cord
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Compare the diffusion of polysynaptic mechanisms and monosynaptic reflexes?
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Polysynaptic mechanisms are more diffuse in influence than the circumscribed monosynaptic reflex and can influence many levels of the spinal cord.
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What is the Bell-Magendie law?
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It states that Afferents enter the spinal cord and Efferents leave the spinal cord.
--This means that the roots of the spinal nerves coming from the ventral portion of the spinal cord are motor in function and those coming from the dorsal portion are sensory |
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Regarding general terms for the elements in a reflex arc, what is the common pattern in nerve transmission from a receptor to an effector?
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Receptor goes to the Afferent path, then to the Central Neuron, then to the Efferent path and finally to the Effector.
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RACEE
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Regarding reflex-arc elements in the monosynaptic stretch reflex, what is the common pattern in nerve transmission from a muscle spindle to a muscle?
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Muscle Spindle goes to Ia fiber then to a Motoneruron then to a Motor axon and then finally to a Muscle.
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MIMMMu
na |
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What is the “transmitter” substance at the monosynaptic reflex?
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Glutamate.
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What is a trisynaptic system?
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a system made of three synapses in the CNS
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When does the Stretch or myotatic reflex occur?
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When the stretch of muscle
with an intact nerve supply results in its reflex contraction |
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What is the receptor for a Stretch or myotatic reflex?
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annulospiral ending.
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What happens when a muscle is quickly stretched?
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it responds by quickly contracting (counteracting the stretch)and this is
demonstrated by tapping a patient’s patellar tendon, which forces the patient to kick as a reflex. |
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What is the net effect of a Stretch or myotatic reflex?
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The net effect is to oppose any stretch of the muscle beyond its present length and this allows for posture.
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What are 2 clinical examples of monosynaptic reflexes?
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1. Knee jerk (patellar reflex)
2. Ankle jerk |
Mo -KA
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What is the Knee jerk (patellar reflex)?
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It is when tapping the patellar tendon causes stretch of the quadriceps femoris muscle and this results in the contraction of the Q. femoris,causing reflex leg extension.
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What is the Ankle jerk?
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It is when tapping the Achilles tendon causes stretch of the gastrocnemius muscle which results in its contraction, producing extension of the limb.
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What is the Muscle Spindle Organ called?
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Stretch Receptor
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What are muscle spindles located within whole muscle called?
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intrafusal fibers (IFF)
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What are intrafusal fibers (IFF)?
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They are specialized muscle tissue which is distinguishable from the extrafusal fiber (EFF) or whole muscle and they are
arranged in parallel with the extrafusal fibers. -- This means that Extrafusal fibers exist OUTSIDE the muscle and IFFs connect with the ends of the muscle mass or sometimes the sides of it. Therefore anything you do with the main muscle mass, the intrafusal fiber follows. It is in parallel with the extrafusal fibers and so anything the EFFs do the IFFs do as well |
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What are the 2 types of IFF?
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1. nuclear bag fiber
2. nuclear chain fiber (smaller than nuclear bag fiber) |
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Where does innervation of the muscle emanate from and where are golgi tendons located?
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Innervation emanates from the muscle spindles and the Golgi tendons are at the ends of the muscle masses.
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What are afferent fibers?
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It is sensory innervation which transmits information from the IFF to the CNS
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What are the 2 types of afferent fibers?
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1. Group 1a
2. Group II |
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What is the role of Group Ia affererent fibers?
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They participate in rate or velocity of stretch (dynamic); and actual amount of stretch (static)
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How do the large primary or Ia fiber wrap around the expanded middle of the nuclear bag?
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By means of its annulospiral ending and by wrapping around the bag, it can detect any stretching performed by the muscle.
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What happens to the nuclear bag fiber when the muscle stretches?
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When the muscle stretches, the nuclear bag fiber surrounding the muscle transmits info into the Ia afferent fiber. The Ia afferent fiber then goes into the CNS and synapses on the motor neuron. The motor neuron innervates the extrafusal fiber and the extrafusal fiber contracts the muscle.
Hence, the extrafusal fiber is in parallel with the intrafusal fiber – Stretching one elicits the contraction of the other. |
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Relating stretching of muscles and generation of action potentials?
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When stretching muscle, the IFF inside the muscle is also stretched, and so, a receptor component is generated. This component sends action potentials into CNS, which eventually allows the muscle to contract.
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What do you do suppose that a patient did not elicit a knee-jerk reflex?
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The patient may be voluntarily controlling his or her reflex, or only one leg elicited the reflex.
If this occurs, try the Jendrassik maneuver. |
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What is the Jendrassik maneuver ?
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It is when you ask patient to hook hands together and pull. The Jendrassik maneuver facilitates the reflex because the response may be “blocked out” by a talkative patient.
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What are 2 potential reasons for why no reflex occurs during a knee jerk or ankle jerk reflex?
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1. A Problem in pathway may exist.
2. A Problem may exist in the dorsal or ventral root component, or a lesion may be present. 3. Muscular or obese patients may not elicit a reflex. |
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What are the 2 factors that the group Ia afferent fibers respond to?
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1) How rapid was the rate of stretching? (how dynamic the stretch was)
2) By how much did it stretch? (how static the stretch was) |
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What is the role of the Primary endings of Group Ia fibers ? and where do they channel their information?
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They also synapse on nuclear chain fibers.Once again, Group Ia fibers are sensitive to the rate (velocity) of stretching and the amount (degree) of stretching.
They channel information over the Ia fiber to the CNS. |
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Why are Group Ia fibers involved in monosynaptic reflexes?
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because they can synapse directly onto alpha motoneurons in the spinal cord.
--From the 1A afferents they go into the spinal cord and synapse directly on the 1A motor neuron NOTE: since 1As wrap around nuclear bag and chain fibers. They may therefore have both dynamic and static fibers |
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Describe Group II (secondary fiber)?
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They are involved in actual stretch (static)and they are
smaller than group Ia. They have flower spray endings on the end portions of the nuclear chain fibers. |
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Endings of Group II (secondary fiber) are sensitive to what?
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the amount (degree) of stretch only.
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What is the difference between nuclear bag fibers and nuclear chain fibers?
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Nuclear bag fibers respond to the rate of stretch (dynamic stretch) and to the actual stretch (static stretch)but nuclear chain fibers respond only to actual (static) stretch only. It wraps around the nuclear bag fibers.
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What are Spinal Reflexes (SR)?
|
Spinal reflexes describe a library of simple postural and movement programs used by an organism.
- They are automatic stereotyped reactions. |
|
|
|
Spinal Reflexes are responses to what?
|
adequate stimulation, without conscious, voluntary actions.
|
|
|
|
What is Adequate stimulation ?
|
It is the form of energy to which a receptor is most sensitive.
|
|
|
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What is a reflex arc?
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The complete nervous path that is involved in a reflex
|
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What are the 2 types of reflex arcs?
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1. Monosynaptic reflex
2. Polysynaptic reflex |
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Differentiate between the 2 types of reflex arcs?
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1. Monosynaptic reflex is the simplest reflex arc, and it consists of a single central synapse between the afferent fiber and the motoneuron
2. Polysynaptic reflex has one or more interneurons between the afferent fiber and the motoneuron. The majority of the spinal reflexes are polysynaptic in nature. |
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What is an example of a monosynaptic reflex?
|
stretch or myotatic reflex
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1. Any type of receptor structure sends information to where?
2. What should you consider when naming a reflex arc ? |
1. the CNS
2. only the number of synapses in the CNS (ignore synapses at the effector organ) |
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Whay may happen to Collaterals from afferent fibers involved in polysynaptic reflexes ?
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They may spread up and down several segments of the spinal cord
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Compare the diffusion of polysynaptic mechanisms and monosynaptic reflexes?
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Polysynaptic mechanisms are more diffuse in influence than the circumscribed monosynaptic reflex and can influence many levels of the spinal cord.
|
|
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What is the Bell-Magendie law?
|
It states that Afferents enter the spinal cord and Efferents leave the spinal cord.
--This means that the roots of the spinal nerves coming from the ventral portion of the spinal cord are motor in function and those coming from the dorsal portion are sensory |
|
|
|
Regarding general terms for the elements in a reflex arc, what is the common pattern in nerve transmission from a receptor to an effector?
|
Receptor goes to the Afferent path, then to the Central Neuron, then to the Efferent path and finally to the Effector.
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RACEE
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Regarding reflex-arc elements in the monosynaptic stretch reflex, what is the common pattern in nerve transmission from a muscle spindle to a muscle?
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Muscle Spindle goes to Ia fiber then to a Motoneruron then to a Motor axon and then finally to a Muscle.
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MIMMMu
na |
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What is the “transmitter” substance at the monosynaptic reflex?
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Glutamate.
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What is a trisynaptic system?
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a system made of three synapses in the CNS
|
|
|
|
When does the Stretch or myotatic reflex occur?
|
When the stretch of muscle
with an intact nerve supply results in its reflex contraction |
|
|
|
What is the receptor for a Stretch or myotatic reflex?
|
annulospiral ending.
|
|
|
|
What happens when a muscle is quickly stretched?
|
it responds by quickly contracting (counteracting the stretch)and this is
demonstrated by tapping a patient’s patellar tendon, which forces the patient to kick as a reflex. |
|
|
|
What is the net effect of a Stretch or myotatic reflex?
|
The net effect is to oppose any stretch of the muscle beyond its present length and this allows for posture.
|
|
|
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What are 2 clinical examples of monosynaptic reflexes?
|
1. Knee jerk (patellar reflex)
2. Ankle jerk |
Mo -KA
|
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What is the Knee jerk (patellar reflex)?
|
It is when tapping the patellar tendon causes stretch of the quadriceps femoris muscle and this results in the contraction of the Q. femoris,causing reflex leg extension.
|
|
|
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What is the Ankle jerk?
|
It is when tapping the Achilles tendon causes stretch of the gastrocnemius muscle which results in its contraction, producing extension of the limb.
|
|
|
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What is the Muscle Spindle Organ called?
|
Stretch Receptor
|
|
|
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What are muscle spindles located within whole muscle called?
|
intrafusal fibers (IFF)
|
|
|
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What are intrafusal fibers (IFF)?
|
They are specialized muscle tissue which is distinguishable from the extrafusal fiber (EFF) or whole muscle and they are
arranged in parallel with the extrafusal fibers. -- This means that Extrafusal fibers exist OUTSIDE the muscle and IFFs connect with the ends of the muscle mass or sometimes the sides of it. Therefore anything you do with the main muscle mass, the intrafusal fiber follows. It is in parallel with the extrafusal fibers and so anything the EFFs do the IFFs do as well |
|
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What are the 2 types of IFF?
|
1. nuclear bag fiber
2. nuclear chain fiber (smaller than nuclear bag fiber) |
|
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Where does innervation of the muscle emanate from and where are golgi tendons located?
|
Innervation emanates from the muscle spindles and the Golgi tendons are at the ends of the muscle masses.
|
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What are afferent fibers?
|
It is sensory innervation which transmits information from the IFF to the CNS
|
|
|
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What are the 2 types of afferent fibers?
|
1. Group 1a
2. Group II |
|
|
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What is the role of Group Ia affererent fibers?
|
They participate in rate or velocity of stretch (dynamic); and actual amount of stretch (static)
|
|
|
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How do the large primary or Ia fiber wrap around the expanded middle of the nuclear bag?
|
By means of its annulospiral ending and by wrapping around the bag, it can detect any stretching performed by the muscle.
|
|
|
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What happens to the nuclear bag fiber when the muscle stretches?
|
When the muscle stretches, the nuclear bag fiber surrounding the muscle transmits info into the Ia afferent fiber. The Ia afferent fiber then goes into the CNS and synapses on the motor neuron. The motor neuron innervates the extrafusal fiber and the extrafusal fiber contracts the muscle.
Hence, the extrafusal fiber is in parallel with the intrafusal fiber – Stretching one elicits the contraction of the other. |
|
|
|
Relating stretching of muscles and generation of action potentials?
|
When stretching muscle, the IFF inside the muscle is also stretched, and so, a receptor component is generated. This component sends action potentials into CNS, which eventually allows the muscle to contract.
|
|
|
|
What do you do suppose that a patient did not elicit a knee-jerk reflex?
|
The patient may be voluntarily controlling his or her reflex, or only one leg elicited the reflex.
If this occurs, try the Jendrassik maneuver. |
|
|
|
What is the Jendrassik maneuver ?
|
It is when you ask patient to hook hands together and pull. The Jendrassik maneuver facilitates the reflex because the response may be “blocked out” by a talkative patient.
|
|
|
|
What are 2 potential reasons for why no reflex occurs during a knee jerk or ankle jerk reflex?
|
1. A Problem in pathway may exist.
2. A Problem may exist in the dorsal or ventral root component, or a lesion may be present. 3. Muscular or obese patients may not elicit a reflex. |
|
|
|
What are the 2 factors that the group Ia afferent fibers respond to?
|
1) How rapid was the rate of stretching? (how dynamic the stretch was)
2) By how much did it stretch? (how static the stretch was) |
|
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The Group Ia afferent fiber has what that allows it to wrap around the expanded middle of a muscle’s nuclear bag?
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It has an annulospiral ending that allows it to wrap around the expanded middle of a muscle’s nuclear bag. By wrapping around the bag, it can detect any stretching performed by the muscle.
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Differentiate btw
1. nuclear bag fibers and 2. nuclear chain fibers |
1. nuclear bag fibers respond to the rate of stretch (dynamic stretch) and to the actual stretch (static stretch).
2. nuclear chain fibers respond only to actual (static) stretch only. It wraps around the nuclear bag fibers. |
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The 3 things that Ia afferent responds to and wraps around are?
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1) The dynamic nuclear bag filter
2) The static nuclear bag fiber 3) The nuclear chain fibers |
SDN
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1. Describe muscle spindles?
2. What are the 2 types of muscle spindles? |
1. Muscle spindles are located entirely inside the muscle; it is a primitive muscle itself
2. The two types of muscle spindles are a. nuclear bag fibers b. nuclear chain fibers |
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Discuss the amount of nuclear bag fibers and nuclear chain fibers?
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There are usually 2 nuclear bag fibers and 5 or 6 chain fibers
Nuclear bag fibers have striated ends; rest of bag is not striates. Same for nuclear chain fibers |
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What are the two types of nuclear bag fibers?
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They respond to actual stretch or rate of stretch– how fast or slow you stretch it and the 2 types are:
1. Those responding to actual stretch = static fibers. 2. those that respond to rate of stretch = dynamic fibers |
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Are Nuclear chain fibers static or dynamic?
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Nuclear chain fibers are always static!!
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Compare the endings of:
1. Group 1a 2. Group II |
1. Group I 1a Aff. = Primary with annulospiral ending
2. Group II = Secondary with flower spray endings |
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What do sensory neurons deal with on the muscle?
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Sensory neurons deal with spindles only.
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What are the are two types of motor fibers?
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1) gamma motor neurons of Leksel (make 30% of ventral horn fibers), which act on the spindles
2) alpha motor neurons, which acts on the extrafusal fiber or main muscle mass. |
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Describe the route that the gamma motor neuron can take?
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Gamma motor neuron can divide into :
1. Plate 2. Trail The plate will then go to the nuclear fiber bag where it will then divide into: 1. Static 2. Dynamic The trail will go the nuclear fiber chain and then go to the static chain division. |
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Where are Nuclear chain fibers attached to?
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They are attached to the ends of the nuclear bag fibers and nuclear chain fibers are shorter and thinner than nuclear bag fibers.
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How do you get the diameter of the CNS fiber? and how do you get the conduction velocity?
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-Divide the conduction velocity by 6 to get the diameter of fiber.
-Multiply the diameter by 6 to get the conduction velocity so a 4-12 micron diameter = 24 to 72m/sec conduction velocity NOTE: the conduction velocity of the Ia afferent fibers is indicated here: 70-120 m/s. Also,For every two nuclear bag fibers, we have 4 nuclear chain fibers. |
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What are the Motor neurons coming off ventral horn and where do they go to bring about contraction of the spindle?
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The motor neurons are gamma motor neurons of leksel and they go to striated ends of the spindle to bring about contraction of the spindle.
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Compare the endings of:
1. Dynamic gamma 2. Static gamma |
1. Dynamic gamma—endings are plate endings (they look like neuromuscular end plates)
2. Static gamma– trail endings |
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What is the sensory component?
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Sensory component: Ia (primary) fibers act due to static and dynamic stretching events of the muscle in the diagram. The II (secondary) fibers only act on the static events.
NOTE: Secondary endings are located towards the ends of the fibers. |
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Why is there a high density of spindle per unit tissue in small muscles?
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Because, in small muscles like muscles of the eye, they are needed for fine movement like fingers; The distribution per unit tissue is much less for trunk muscles.
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Dynamic and static fibers adjust to what?
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sensitivity of movements that are taking place (EFF and IFF adjust to changes in movement)
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What happens when there is Pre-stretching of EFF (bringing it closer to threshold)?
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It adjusts to threshold of sensitivity (lowering threshold) and this allows for changes in terrain and in movement. It is important in POSTURE AND MOVEMENT
note: They are type A fibers! (gamma?) |
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What do group Ia afferent fibers respond to?
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both static and dynamic stretching of muscle.
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Muscle spindle is in parallel with what?
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with the extrafusal fibers
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What happens Whenever you stretch the muscle spindle by tapping the patella (stretches quadriceps femoris) ?
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They are stretched also in passive (assisted) stretch of the muscle
-When muscle is stretched info travels from annulospiral endings by 1A fibers to direct directly on the alpha motor neuron (blue circle)—synapse is in the ventral horn. -Alpha motor neuron then causes the EFF to shorten (stereotypical shortening of the muscle) = monosynaptic reflex |
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What does the small gamma motor neurons of Leksel innervate and what is the consequence of this innervation?
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They innervate the ends of the IFF (contractile ends) and this causes shortening of the spindle– not a full firing or contraction but a little tease of the spindle. This then modifies the sensitivity of the threshold to adjust to the terrain.
That brings about facilitation to adjust to different terrains and movements. |
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Describe the gamma loop?
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It is the gamma motor neuron from the ventral horn that acts on the 1A fiber to stimulate a change via the alpha motor neuron. It is important in lesions in the spinal cord and postural muscle
-So, to test the gamma loop– do no cut anything ventral because then you cannot have muscle contraction. With lesions of the dorsal horn you can find out if you have a gamma problem. |
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Describe the role of the alpha motor neuron?
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It is the final common pathway to the effector organ so if it is cut there will be no more effect = flaccid paralysis of the muscle
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Describe the motorneuron?
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The excitatory and inhibitory influences converge onto a motoneuron and the motoneuron is the “final common path”.
-so this is like an algebraic sum of effects gives you a combined outcome |
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What is reciprocral innervation?
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It is when there is innervation so that the contraction of a muscle or a set of muscles (as of a joint) is accompanied by the simultaneous inhibition of an antagonistic muscle or set of muscles
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illustrate an example of reciprocral innervation?
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If you tap the patella tendon, you expect a kick
because shortening of the muscle leads to contraction of the quad femoris but the flexor muscle is prevented from contracting by the inhibitory interneuron pathway. |
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What neurotransmitter is used in the inhibitory pathway that inhibits the flexors’ alpha motor neuron?
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GLYCINE
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What is the patella tendon reflex and how does it affect other muscles?
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The reflex is monosynaptic but it affects other muscles via the inhibitory interneuron
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Describe the golgi tendon organ?
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-It is in the tendon of the muscle and its nerve endings scattered around.
-It also has collagen fibers that wrap around the axon and influence its activity |
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What afferents are involved in the golgi tendon organ?
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1B afferents are involved .
-When muscle gives in under excessive weight is because of this or else you would tear the muscle |
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Differentiate between:
1. 1A afferent 2. IB afferent |
1.1A afferent gives contraction by way of alpha motor neuron.
1. 1B afferent from tendon inhibits the alpha motor neuron via an inhibitory interneuron but the threshold for 1B afferent to bring about inhibition is low (but it works with high exertion of muscle– muscle stretch must be over come before you trigger the inhibitory pathway for the alpha motor neuron |
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What happens when weight causes passive stretch of the EFF?
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There is an increase in Action Potentials (frequency modulation)– this is with muscle spindles
-Likewise, |
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Compare in terms of action potentials (AP) generated:
1. A2 2. B1 3. B2 |
1. A2 = golgi tendon organ passive stretch = increase in APs
2. B1 = muscle spindle = nerve stimulation of associated muscle = not much AP generated. Therefore the spindle is quiet…why? 3. B2 = golgi tendon organ = nerve stimulation of associated muscle = increased APs. Therefore the golgi tendon organ responds to passive stretch less than muscle spindle, but reacts MORE to tension in the muscle |
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Why is there a marked response in the golgi tendon organ when it is stimulated?
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Because golgi tendon organ is in series
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What are the 2 things that the golgi tendon organ (GTO) responds to?
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1. Passive stretch
2. Active stretch |
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Differentiate between regulation in:
1. Spindle 2. Golgi tendon organ (GTO) |
1. Spindle regulates muscle Length
2. GTO regulates muscle Force Tension |
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Describe:
1. Threshold of GTO 2. Lengthening reaction of GTO |
1. Threshold: Low
2. Lengthening Reaction (clasp knife effect) |
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What happens when you stretch a muscle with spastically increased tone?
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There is increased muscle tension (stretch reflex)
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What happens when there is extreme stretching of a muscle?
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It causes sudden decrease in muscle tone due to GTO
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What is a renshaw cell?
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It is an internuncial neuron in the ventral horn of gray matter of the spinal cord that has an inhibitory effect on motoneurons
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1.Describe the polysynaptic reflex?
2. The final Final common pathway or output neuron may be what? |
1. It has an Input neuron with several branches.
2. the alpha motor neuron |
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What happens when you have more synapses?
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There is a quicker response time because there is less synaptic delay to deal with
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Describe a reverberating circuit?
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They are are never-ending cyclical pathways so after you get effect there is an after discharge because the stimulation keeps going round and round with some activating themselves over and over again
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What happens when there are inhibitory pathways included?
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It will cause a delay but not a cessation in transmission of the information
Note: Renshaw pathway! |
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Describe the flexor withdrawal reflex?
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It is a simple polysynaptic reflex that results in flexion on the ipsilateral side and extension on the contralateral side.
-The flexors have a nociceptive trigger at the surface of the skin so pain (e.g., touching a hot stove) stimulates the flexor reflex afferents of groups II, III, IV. -Higher center input can overcome this normally overridding reflex to drop hot stuff for ex, if it is important and you want to place it down gently , so you have to hold on to it longer than reflex wants you to. |
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Describe the crossed extensor reflex?
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This happens when stimulus of the skin brings about inhibition of extensors on ipsilateral side(they relax); or inhibit flexors and activate extensors on contralateral side in order to maintain balance.
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Give an example of each:
1. Stretch reflex 2. Golgi tendon reflex 3. Flexor-withdrawal reflex |
1. Stretch reflex = knee jerk
2. Golgi tendon reflex = clasp - knife 3. Flexor-withdrawal reflex = after touching a hot stove |
SGF = KCS
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Compare the number of synapses in:
1. Stretch reflex 2. Golgi tendon reflex 3. Flexor-withdrawal reflex |
1. Stretch reflex = monosynaptic
2. Golgi tendon reflex = disynaptic 3. Flexor-withdrawal reflex = Polysynaptic |
SGF = MDP
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Identify the stimulus for:
1. Stretch reflex 2. Golgi tendon reflex 3. Flexor-withdrawal reflex |
1. Stretch reflex = Muscle is streched
2. Golgi tendon reflex = Muscle is contracted 3. Flexor-withdrawal reflex = Pain |
SGF = SCP
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Identify the afferent fibers for:
1. Stretch reflex 2. Golgi tendon reflex 3. Flexor-withdrawal reflex |
1. Stretch reflex = Ia
2. Golgi tendon reflex = Ib 3. Flexor-withdrawal reflex = II, III, IV |
1 (a, b), 2, 3, 4
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Identify the responses for:
1. Stretch reflex 2. Golgi tendon reflex 3. Flexor-withdrawal reflex |
1. Stretch reflex = contraction of the muscle
2. Golgi tendon reflex = Relaxation of the muscle 3. Flexor-withdrawal reflex = ipsilateral flexion; contralateral extension |
CRIp founder
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2 Characteristics of Polysynaptic Reflexes?
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1. Prolonged – with irradiation or recruitment of motor units
a. prolonged firing of motor units b. reverberating circuits ; spread may extend to all 4 -extremities 2. Pre-potent: i.e., override or preempt spinal pathways from other reflex activity |
P = PP
i r |
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Use the limbs to describe The Crossed Extensor Reflex?
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1. stimulate medial surface of limb: response = abduction
2. stimulate lateral surface of limb: response = adduction NOTE: Local sign – this varies with part of the body stimulated |
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What are 4 events that can occur due to Polysynaptic Reflexes?
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1. After-discharge
2. Spatial and temporal facilitation 3.Reaction time shortened as stimulus strength is increased 4. Occlusion |
ASSO police
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What is After-discharge?
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It is a prolonged response due to repeated firing of motor neurons
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Distinguish between the 4 classification of nerve fibers?
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1. Group I = Primary muscle - spindle afferents and afferents from tendon organs
2. Group II: Cutaneous mechanoreceptors 3. Group III: Deep pressure sensors in muscle 4. Group IV: Unmyelinated pain fibers |
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