Self Assessment 04/07/2024 Flashcards
Which of the following motor subsystems plays an important role in the selection of appropriate motor plans and the suppression of inappropriate plans?
A. Cerebellum
B. Lower motor neurons and local circuit neurons.
C. Descending systems carrying commands generated by upper motor neurons.
D. Basal nuclei
D. Basal Nuclei
Explanation:
The basal nuclei prepare UMN circuits for the initiation of desired movements and the suppression of unwanted movements. Thus, they are the key to the proper gating of the initiation and termination of motor plans.
Which of the following movements would be considered a reflexive movement?
A. Reaching for a can of soda.
B. Removing your hand from a hot stove.
C. Hitting a ball with a baseball bat.
D. Walking down the street.
B. Removing your hand from a hot stove.
Explanation:
Pain receptors would transmit this information from the periphery and stimulate motor neurons at the level of the spinal cord to activate a flexor withdrawal response of the arm, so that the hand is reflexively removed from the hot stimulus.
Voluntary movements are consciously controlled, have a flexible context-dependent association with sensory stimuli, and they can improve with practice or experience.
A. True
B. False
A. True
Explanation:
The above characteristics are consistent with voluntary movements. Reflexive movements are involuntary stereotyped movements made in response to a sensory stimulus
Which of the following statements regarding lower motor neurons (LMNs) is false?
A. LMN pools that innervate the upper extremity are located in the cervical enlargement of the spinal cord.
B. LMN pools located medially in the ventral horn innervate muscles that will control movements of the trunk (axial muscles).
C. LMNs encode the force generated by individual muscles via the rate code and the size principle of recruitment.
D. LMNs receive sensory input from the periphery and modulatory input from upper motor neurons located in the motor cortices and brainstem.
E. There are two types of LMNs. Alpha motor neurons innervate intrafusal muscle fibers and gamma motor neurons innervate extrafusal muscle fibers.
E. There are two types of LMNs. Alpha motor neurons innervate intrafusal muscle fibers (FALSE) and gamma motor neurons innervate extrafusal muscle fibers (FALSE).
Explanation:
The first part of the statement is true: there are two types of LMNs. However, the second part of the statement is false: alpha motor neurons innervate the force generating fibers (extrafusal) of skeletal muscle, while gamma motor neurons innervate the contractile part of the muscle spindle (intrafusal fiber).
Damage to lower motor neurons will result in a combination of clinical signs. Which of the following signs are associated with LMN damage?
A. Fibrillations or fasciculations
B. Hyporeflexia or areflexia
C. Spasticity or hypertonicity
D. Both A & B
E. Both B & C
D. Both A & B
Explanation:
Since fibrillations or fasciculations, and hyporeflexia or areflexia are all LMN signs, both A and B are correct responses.
Which of the following upper motor neuron pathways modulates the activity of lower motor neuron pools that innervate muscles associated with postural control?
A. Lateral corticospinal Tract
B. Anterior corticospinal tract
C. Reticulospinal tract
D. Both B & C
D. Both B & C
Explanation
ACST is an upper motor neuron pathway originating in the motor cortex. It modulates the activity of lower motor neuron pools that innervate axial and proximal limb musculature (e.g., trunk, shoulder, hip). Thus, it is a correct answer, but it is not the only correct answer as the reticulospinal tracks also modulate muscles associated with postural control
The ______________ and the ____________ make up the primary motor cortex.
A. Postcentral and posterior paracentral gyri
B. Precentral and anterior paracentral gyri
C. Middle frontal gyrus
D. None of the above
B. Precentral and anterior paracentral gyri
Explanation:
Both the precentral (face, UE representations) and anterior paracentral (LE representation) make up the primary motor cortex.
Apraxia is the inability to execute actions in the absence of paresis or paralysis.
A. True
B. False
A. True
Which of the following disorders results from damage to the subthalamic nucleus?
A. Huntington’s Disease
B. Parkinson’s Disease
C. Hemiballismus
D. Both A & C
C. Hemiballismus
Explanation:
Hemiballismus is caused by damage to the subthalamic nucleus.
Which of the following statements regarding the direct pathway of the basal nuclei is false?
A. The striatum receives excitatory input from the cortex and the substantia nigra pars compacta.
B. The striatum sends excitatory projections to the internal segment of the globus pallidus.
C. The net effect of the direct pathway is to excite UMNs in the motor cortices.
D. An imbalance in the output of the basal nuclei that favors the indirect pathway will result in a reduction in voluntary motor activity.
B. he striatum sends excitatory projections to the internal segment of the globus pallidus.
Explanation:
Statement C is true because when the striatum is stimulated by the cortex and the pars compacta, it sends inhibitory input to the globus pallidus. This results in the shutting down of the tonic inhibitory input from the globus pallidus to the thalamus. Thus, the thalamus is released from inhibition which results in the excitation of UMNs in the motor cortices.
