Podcast
Questions and Answers
What is a motor unit?
What is a motor unit?
- Alpha motor neurons and muscle fibers that activate it (correct)
- Signals in the sensory dorsal horn
- Group of muscles innervated by a single spinal nerve
- Muscles activated together in a healthy normal system
Why is communication of sensory, motor & interneurons important?
Why is communication of sensory, motor & interneurons important?
- To inhibit contraction of agonist muscles
- To prevent injury and coordinate muscle action (correct)
- To activate antagonist muscles for fluid motion
- To control the timing and degree of muscle action
What is the function of reciprocal inhibition?
What is the function of reciprocal inhibition?
- To activate synergistic muscles
- To inhibit contraction of antagonist muscles (correct)
- To sense change in muscle spindles
- To send signals to the sensory dorsal horn
What is the role of myotome in the motor system?
What is the role of myotome in the motor system?
Which of the following is a characteristic of the clasp knife response?
Which of the following is a characteristic of the clasp knife response?
What is myoplasticity?
What is myoplasticity?
What can cause contracture leading to further weakness?
What can cause contracture leading to further weakness?
What does hypotonia refer to?
What does hypotonia refer to?
What is a characteristic of spinal shock?
What is a characteristic of spinal shock?
What is the result of complete motor neuron lesions?
What is the result of complete motor neuron lesions?
What is the presentation of upper motor neuron lesions?
What is the presentation of upper motor neuron lesions?
What is the result of a lower motor neuron lesion?
What is the result of a lower motor neuron lesion?
What are the characteristics of deceberate posturing?
What are the characteristics of deceberate posturing?
What is a characteristic of babinski sign in the context of motor neuron lesions?
What is a characteristic of babinski sign in the context of motor neuron lesions?
What is the impact of a lesion affecting motor tracts on muscle synergies?
What is the impact of a lesion affecting motor tracts on muscle synergies?
What type of signaling from the periphery, interneurons, and motor neurons provides proprioception?
What type of signaling from the periphery, interneurons, and motor neurons provides proprioception?
Which structure informs about tendon tension and lengthening, affecting muscle activation through spinal interneurons?
Which structure informs about tendon tension and lengthening, affecting muscle activation through spinal interneurons?
What coordinates a rudimentary stepping pattern by connecting sensory and motor signals at or near the spinal level?
What coordinates a rudimentary stepping pattern by connecting sensory and motor signals at or near the spinal level?
What type of stretch activates afferent nerves to the spinal cord, initiating a reflex?
What type of stretch activates afferent nerves to the spinal cord, initiating a reflex?
Which reflex coordinates muscle activation in response to a noxious stimulus, occurring at multiple spinal levels without the need for cortical input?
Which reflex coordinates muscle activation in response to a noxious stimulus, occurring at multiple spinal levels without the need for cortical input?
What do motor nerve conduction velocity tests help identify?
What do motor nerve conduction velocity tests help identify?
What does electromyography measure in muscles?
What does electromyography measure in muscles?
What does heightened muscle activity with needle electromyography indicate?
What does heightened muscle activity with needle electromyography indicate?
What can be identified through electromyography and nerve conduction studies?
What can be identified through electromyography and nerve conduction studies?
Which tracts within the spinal cord convey signals for movement and muscle activation to different parts of the body?
Which tracts within the spinal cord convey signals for movement and muscle activation to different parts of the body?
Which motor tracts are responsible for controlling posture and muscle innervation?
Which motor tracts are responsible for controlling posture and muscle innervation?
Which tracts form the emotional motor system, impacting movement in response to emotions?
Which tracts form the emotional motor system, impacting movement in response to emotions?
Which motor tract primarily innervates axial and girdle musculature, facilitating posture and core strength?
Which motor tract primarily innervates axial and girdle musculature, facilitating posture and core strength?
Where are the cell bodies for the medial corticospinal tract located?
Where are the cell bodies for the medial corticospinal tract located?
Where does the reticulospinal tract begin?
Where does the reticulospinal tract begin?
Which motor tract responds to signals coming from the inner ear, helping orient the body towards gravity?
Which motor tract responds to signals coming from the inner ear, helping orient the body towards gravity?
Where do the medial motor tracts arise?
Where do the medial motor tracts arise?
Which tracts in the spinal cord are responsible for distal limb movement and fractionation of movements?
Which tracts in the spinal cord are responsible for distal limb movement and fractionation of movements?
Where does the Lateral Corticospinal Tract start?
Where does the Lateral Corticospinal Tract start?
Which tract begins at the red nucleus in the midbrain and plays a smaller role than the lateral corticospinal tract?
Which tract begins at the red nucleus in the midbrain and plays a smaller role than the lateral corticospinal tract?
Which of the following is a motor system dysfunction characterized by repeated, involuntary, rhythmic contractions of a single muscle group?
Which of the following is a motor system dysfunction characterized by repeated, involuntary, rhythmic contractions of a single muscle group?
What is the term for the motor system dysfunction that includes abnormal reflexes like Babinski's sign?
What is the term for the motor system dysfunction that includes abnormal reflexes like Babinski's sign?
What is the term for the motor system dysfunction characterized by heightened muscle activity with needle electromyography?
What is the term for the motor system dysfunction characterized by heightened muscle activity with needle electromyography?
Which motor system dysfunction includes abnormal reflexes like Babinski's sign and tonic stretch reflex?
Which motor system dysfunction includes abnormal reflexes like Babinski's sign and tonic stretch reflex?
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Study Notes
Motor System: Spinal Cord and Nerve Assessment
- Type 2 afferent signaling from periphery, interneurons, and motor neurons provides proprioception, informing about the body's position in space and time.
- The Golgi tendon organ informs about tendon tension and lengthening, affecting muscle activation through spinal interneurons.
- A rudimentary stepping pattern is coordinated by a highway of interneurons connecting sensory and motor signals at or near the spinal level.
- Phasic stretch, such as the reflex hammer stretch to the patellar tendon, activates afferent nerves to the spinal cord, initiating a reflex.
- The withdrawal/crossed extension reflex coordinates muscle activation in response to a noxious stimulus, occurring at multiple spinal levels without the need for cortical input.
- Motor nerve conduction velocity tests locate areas of damage along muscle activation, helping to identify problems in motor nerves, neuromuscular junctions, or muscles.
- Electromyography measures electric activity in muscles, aiding in understanding the location of lesions in the motor nervous system.
- Motor neuron lesions result in heightened muscle activity with needle electromyography, while motor tract lesions may present with degeneration in specific tracts.
- Myopathy, damage to the muscle itself, can be identified through electromyography and nerve conduction studies.
- Vertical motor tracts within the spinal cord convey signals for movement and muscle activation to different parts of the body.
- Medial motor tracts, including the reticulospinal, medial vestibulospinal, and lateral vestibulospinal tracts, are responsible for controlling posture and muscle innervation.
- Nonspecific motor tracts, such as the ceruleospinal and raphespinal tracts, form the emotional motor system, impacting movement in response to emotions.
Motor Tracts and Dysfunctions in the Spinal Cord
- Medial corticospinal tract primarily innervates axial and girdle musculature, facilitating posture and core strength
- Cell bodies for these tracts are located in the medial anterior horn of the gray area of the spinal cord
- Automatic motor control primarily coordinated at the brainstem level, where these 3 tracts derive
- Reticulospinal Tract begins in the reticular formation of the brainstem, sending signals to both ipsilateral and contralateral motor neurons at the spinal level
- Lateral Vestibulospinal Tract responds to signals coming from the inner ear, helping orient the body towards gravity
- Medial Vestibulospinal Tract responds to signals regarding head movement and position, activating and coordinating muscle activity in the neck and upper back
- Medial Motor Tracts arise in the primary motor cortex and supplementary motor area within the cortex, providing signals for bilateral control of axial and upper girdle muscles
- Lateral Tracts in the spinal cord responsible for distal limb movement and fractionation of movements
- Lateral Corticospinal Tract starts at the premotor cortex, descending downwards through the spinal cord
- Rubrospinal Tract begins at the red nucleus in the midbrain and plays a smaller role than the lateral corticospinal tract
- Motor System Dysfunctions include paresis vs paralysis, abnormal reflexes like Babinski's sign, and phasic stretch hyperreflexia
- Motor System Dysfunctions also include tonic stretch reflex and clonus, which are repeated, involuntary, rhythmic contractions of a single muscle group
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