22 Questions
What is a consequence of damaged descending cortical fibers?
Repetitive, sequential contraction of ankle flexors and extensors
Which of the following is NOT a condition in which clonus may be seen?
Parkinson's disease
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
What is the primary location of damage causing decorticate posturing?
Upper midbrain
What is a key difference between decerebrate and decorticate posturing?
Extension vs. flexion of upper limbs
Which of the following is a feature of decorticate posturing?
Flexed upper limbs
What is the relationship between clonus and upper motor neuron lesions?
Clonus is a characteristic of upper motor neuron lesions
Which of the following conditions is LEAST likely to exhibit decerebrate posturing?
Epilepsy
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
What is the characteristic feature of clonus?
Regular, repetitive, rhythmic contractions of a muscle
What is the neurotransmitter released at the central synapse in a monosynaptic reflex?
Glutamate
What is the term for a reflex arc with a single synapse between the afferent and efferent neurons?
Monosynaptic reflex
What is the response to the stretch of a skeletal muscle with an intact nerve supply?
Contraction of the muscle being stretched
What is the typical example of a monosynaptic reflex?
Knee jerk reflex
What is the characteristic feature of states with increased motor neuron activity?
Clonus
What is the minimum number of beats required to consider ankle clonus as abnormal?
5
What is the primary mechanism that contributes to ankle clonus?
Inverse stretch reflex sequence without Golgi tendon organ activation
What type of injury can disrupt the descending cortical input to the Renshaw cell?
Spinal cord injury
What is the function of the Renshaw cell in the neural circuitry?
Inhibition of alpha motor neurons
What is the role of cortical fibers in the neural circuitry?
Activation of Renshaw cells and type Ia inhibitory interneurons
What is the result of synchronized motor neuron discharge in ankle clonus?
Rhythmic plantar flexion
What is the consequence of spindle discharge in ankle clonus?
Spindle discharge cessation
Learn about the simplest reflex arc, monosynaptic reflexes, and how they differ from polysynaptic reflexes. Understand the response of skeletal muscles to stretching.
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