Monosynaptic Reflexes and Stretch Reflex

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What is a consequence of damaged descending cortical fibers?

Absence of clonus

Repetitive, sequential contraction of ankle flexors and extensors (correct)

Isolation of motor neuron lesions

Enhanced inhibition of antagonists

Which of the following is NOT a condition in which clonus may be seen?

Epilepsy

Parkinson's disease (correct)

Amyotrophic lateral sclerosis (ALS)

Spinal cord damage

What is the characteristic posture of decerebrate posturing?

Extended lower extremities with toes pointed inward and upper extremities extended with fingers flexed and forearms pronate (correct)

Flexed neck and extended head

Flexed upper limbs and extended lower limbs

Extended upper limbs and flexed lower limbs

What is the primary location of damage causing decorticate posturing?

Upper midbrain Signup and view all the answers

What is a key difference between decerebrate and decorticate posturing?

Extension vs. flexion of upper limbs Signup and view all the answers

Which of the following is a feature of decorticate posturing?

Flexed upper limbs Signup and view all the answers

What is the relationship between clonus and upper motor neuron lesions?

Clonus is a characteristic of upper motor neuron lesions Signup and view all the answers

Which of the following conditions is LEAST likely to exhibit decerebrate posturing?

Epilepsy Signup and view all the answers

What is the primary function of the muscle spindle in a monosynaptic reflex?

To sense the stretch of the muscle and transmit the signal to the CNS Signup and view all the answers

What is the characteristic feature of clonus?

Regular, repetitive, rhythmic contractions of a muscle Signup and view all the answers

What is the neurotransmitter released at the central synapse in a monosynaptic reflex?

Glutamate Signup and view all the answers

What is the term for a reflex arc with a single synapse between the afferent and efferent neurons?

Monosynaptic reflex Signup and view all the answers

What is the response to the stretch of a skeletal muscle with an intact nerve supply?

Contraction of the muscle being stretched Signup and view all the answers

What is the typical example of a monosynaptic reflex?

Knee jerk reflex Signup and view all the answers

What is the characteristic feature of states with increased motor neuron activity?

Clonus Signup and view all the answers

What is the minimum number of beats required to consider ankle clonus as abnormal?

5 Signup and view all the answers

What is the primary mechanism that contributes to ankle clonus?

Inverse stretch reflex sequence without Golgi tendon organ activation Signup and view all the answers

What type of injury can disrupt the descending cortical input to the Renshaw cell?

Spinal cord injury Signup and view all the answers

What is the function of the Renshaw cell in the neural circuitry?

Inhibition of alpha motor neurons Signup and view all the answers

What is the role of cortical fibers in the neural circuitry?

Activation of Renshaw cells and type Ia inhibitory interneurons Signup and view all the answers

What is the result of synchronized motor neuron discharge in ankle clonus?

Rhythmic plantar flexion Signup and view all the answers

What is the consequence of spindle discharge in ankle clonus?

Spindle discharge cessation Signup and view all the answers