22 Questions
Which component is primarily responsible for the connection between the CNS and skeletal muscle contraction units?
Alpha motor neurons
What type of atrophy is caused by damage to the nervous system?
Neurogenic atrophy
Which condition is characterized by quick twitches of muscle fibers visible on the surface of the skin?
Fasciculations
What is the term used to describe abnormally low resistance to passive stretch?
Hypotonia
What symptom is typically not visible except in the tongue?
Fibrillations
What does flaccidity indicate in terms of muscle resistance?
Lack of resistance to passive stretch
What is the primary responsibility of the pyramidal system with regards to lower motor neurons (LMNs)?
To carry cortical commands to LMNs for executing voluntary movements.
Which part of the central nervous system do lower motor neurons primarily influence to achieve voluntary movement?
Spinal cord and brainstem
Where are the cell bodies of lower motor neurons located?
Spinal cord or brainstem
What type of neuron must be intact for normal voluntary movements, according to the lecture?
Both upper and lower motor neurons
Through which route do upper motor neurons send impulses to lower motor neurons?
Through descending tracts to synapse with lower motor neurons or interneurons
From where do the anterior horn cells (AHCs) receive motor impulses?
Pyramidal tract
What influences fine-tuning coordination during movement?
Cerebellum connections with motor cortex and brainstem motor centers
What functional role do muscle receptors play during the execution of movement?
They record muscle stretch and send information back to LMNs and cerebellum.
What is the primary function of alpha motor neurons?
To innervate extrafusal muscle fibers
Where are the cell bodies of lower motor neurons located?
Ventral horn of the spinal cord
What type of axons do gamma motor neurons have?
Medium-sized myelinated axons
Which of the following is true about intrafusal muscle fibers?
They are innervated by gamma motor neurons
Which type of neuron is primarily responsible for regulating muscle tone?
Gamma motor neurons
What happens when an alpha motor neuron releases sufficient ACh?
All of the muscle fibers it innervates contract
What is the primary role of the motor nuclei of cranial nerves?
To form the cell bodies of LMN for the cranial nerves
Which pathway do the axons of alpha and gamma motor neurons follow to reach skeletal muscle?
Ventral root, spinal nerve, peripheral nerve
This quiz covers the description and signs of lower motor neuron lesion, and differentiates between upper motor neuron lesion (UMNL) and lower motor neuron lesion (LMNL).
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