Master the Motor Cortex

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169 Questions

Which area of the motor cortex is responsible for controlling muscles in the hand and muscles concerning speech?

Primary cortex

What is the function of the motor cortex?

Sending commands to the skeletal muscle

What can somatic signals do to muscle contraction?

Enhance muscle contraction

How many areas is the motor cortex divided into?

3

Where does the primary cortex begin?

Laterally in the sylvian fissure

Which area is responsible for motor imaging and contains mirror neurons?

Premotor areas

Where are supplemental areas located?

In the longitudinal fissure

Which area is known as Broca's area and is responsible for motor speech?

Motor speech area

Which area controls bilateral movements such as climbing or grasping an object with both hands?

Supplemental areas

Which area has more complex patterns compared to the primary motor cortex?

Premotor areas

Which tract originates in the red nucleus?

Rubrospinal tract

Which cells are found only in the motor cortex and project down through the spinal cord onto motor neurons?

Betz cells

Which lesions can cause a dramatic increase in extensor tone called decerebrate rigidity?

Lesions above the pons but below the midbrain

Which tract originates in the superior colliculus?

Tectospinal tract

Where do pyramidal tracts decussate?

Lower medulla

Which cells are referred to as magnocellular cells?

Betz cells

Which laminae perform most of the intracortical association functions?

Lamina I, II, and III

Which cells give rise to the output fibers of the cerebral cortex?

Pyramidal and Fusiform cells

Where do most incoming sensory signals terminate within the cerebral cortex?

Lamina IV

Which layer of the primary motor cortex contains pyramidal cells?

Lamina V

Which laminae receive inputs in the primary motor cortex?

Lamina II and IV

Which type of neurons in the red nucleus are more abundant?

Dynamic neurons

Which type of neurons fire at a slower rate and maintain the force of contraction for as long as needed?

Static neurons

Which type of neurons are excited for short periods of time and cause rapid development of force?

Dynamic neurons

Which cells are responsible for transmitting both dynamic and static signals?

Pyramidal cells

Which descending tracts terminate mainly on interneurons and motor nerves?

Corticospinal and rubrospinal tracts

Where is the red nucleus located?

Mesencephalon

Which tract decussates in the lower brain stem and goes into the lateral columns of the spinal cord?

Rubrospinal tract

Which nucleus serves as an alternative pathway for transmitting cortical signals to the spinal cord?

Red nucleus

Which cells give rise to the rubrospinal tract?

Magnocellular cells

Where does the rubrospinal tract originate?

Red nucleus

What is the function of the red nucleus?

Motor coordination

Which portion of the red nucleus is similar in size to Betz cells?

Magnocellular portion

Which lobe of the brain is important for language comprehension?

Temporal lobe

Which area is responsible for word formation in language?

Broca's area

What is the consequence of damage to the angular gyrus in the occipital lobe?

Alexia

Which area is responsible for language comprehension?

Wernicke's area

What is the consequence of damage to Broca's area?

Inability to vocalize words

Which area within the parieto-occipitotemporal area is responsible for visual reading of words?

Angular gyrus

What is the consequence of damage to the arcuate fasciculus?

Impaired speech comprehension

Where are names of objects learned through?

Auditory input

Which area of the brain is responsible for connecting the speech motor areas with the language comprehension area?

Arcuate fasciculus

How are the physical nature of objects learned according to the text?

Through visual input

Which two cortical areas are specialized for language?

Broca's area and Wernicke's area

Where is Wernicke's area located?

Upper part of temporal lobe

How is the understanding of the meaning of words achieved?

Through Wernicke's area

Which tract connects Wernicke's area to Broca's area?

Arcuate fasciculus

What is the consequence of damage to Broca's area?

Inability to produce speech or find a word

What is the consequence of damage to Wernicke's area?

Fluent production of speech with poor comprehension

Which hemisphere is dominant for right-handed people?

Left

Which hemisphere can be dominant for left-handed people?

Right

Which area is important for interpreting complicated meanings of sensory experiences?

Wernicke's area

Which area is used for speaking a written word but not for speaking a heard word?

Angular gyrus

What do fibers in the corpus callosum provide between the two cerebral hemispheres?

Bidirectional information

What types of functions may the non-dominant hemisphere be used for?

Interpreting music and body language

Which disease is the most common form of dementia in the United States?

Alzheimer's disease

Which neurotransmitter is associated with the loss of cholinergic neurons in Alzheimer's disease?

Acetylcholine

Where does degeneration occur in Alzheimer's disease?

Hippocampus

What are the microscopic findings in Alzheimer's disease?

Amyloid-beta plaques and neurofibrillary tangles

Which disease is a leading cause of death from cardiovascular disease in the United States?

Stroke

What is the importance of time in stroke care?

Early care leads to better outcomes

Which type of stroke is caused by an occlusion of a cerebral blood vessel resulting in an infarction?

Ischemic stroke

What is the main cause of hemorrhagic stroke?

Chronic hypertension

Which symptoms can be induced by a stroke?

Paralysis, numbness, and sensory deficits on one side of the body

What can cause an ischemic stroke?

Atherosclerosis, cerebral embolism, or occlusion of a small cerebral vessel

What is the main cause of intracerebral hemorrhage?

All of the below

Which artery supplies the largest portion of the left cerebral hemisphere?

Middle cerebral artery

What symptoms can occur as a result of an occlusion in one of the distal stems of the MCA?

All of the above

What structures can be affected by an infarction in the internal capsule?

Basal ganglia, putamen, and caudate

Which area of the brain is responsible for speech impairment in motor aphasia?

Broca's area

Which artery is associated with occlusion that can cause visual field defects and deviation of the head and eyes towards the side of the lesion?

Middle cerebral artery (MCA)

Which direction do the head and eyes deviate towards when the MCA is occluded?

Towards the side of the lesion

Which area of the cerebellum is responsible for controlling dynamic balance and eye movements?

Vestibulocerebellum

Which area of the cerebellum receives information from the motor cortex and periphery to coordinate movement?

Spinocerebellum

Which area of the cerebellum helps to plan, sequence, and time complex movements?

Cerebrocerebellum

Which zone of the cerebellum is responsible for motor coordination of the axial body, neck, shoulders, and hips?

Vermis

Which zone of the cerebellum controls muscle contractions in the upper and lower limbs, and face?

Intermediate zone

Which zone of the cerebellum joins with the cerebral cortex in overall planning of sequential motor movements?

Lateral zone

Which zones receive information from the cerebral cortex and do not have topographs?

Lateral zones

Which tracts mainly go to the lateral zones?

Pontocerebellar tracts

Which tracts come from the periphery and terminate in vermis and intermediate zones?

Spinocerebellar tracts

Which tracts receive information from the periphery and terminate in the vermis and intermediate zones?

Spinocerebellar tracts

What type of signals do the dorsal spinocerebellar tracts receive?

Proprioceptive signals

Where does the ventral spinocerebellar tract receive information from?

Anterior horns of the spinal cord

Which structures receive efferent signals from the cerebellum?

Thalamus and basal ganglia

Where do deep cerebellar nuclei receive signals from?

Cerebellar cortex and deep sensory afferents

What is the function of the cerebellar cortex in the input signal pathway?

Divides the input signal and sends it to the deep nuclei and cortex

Which layer of the cerebellum is the innermost?

Granular layer

What type of output signal does the purkinje cell layer of the cerebellum provide?

Inhibitory

What type of fibers provide excitatory input to the cerebellar cortex?

Climbing and Mossy fibers

What is the function of the complex circuit in the cerebellum?

Inhibiting agonist and antagonist muscles

Which cells in the cerebellum are responsible for modulating the activity of circuits that go to the deep cerebellar nuclei?

Purkinje cells

What type of fibers provide excitatory input to the Purkinje cells in the cerebellum?

Climbing fibers

What is the function of cerebellar interneurons, except for granule cells?

Inhibitory

What is the consequence of damage to the angular gyrus in the occipital lobe?

Language comprehension difficulties

What is the primary output from the cerebellar cortex?

GABA

What determines the output of the cerebellar cortex?

Deep nuclear cells

What is the role of the deep nuclear cells in the cerebellum?

Receive input from the periphery and brain

What is the function of the complex spikes in the cerebellum?

Elicit multiple excitatory bursts

Which part of the cerebellum is responsible for providing anticipatory correction?

Vestibulocerebellum

What is the function of the climbing fiber in the cerebellum?

To alter the long-term sensitivity of the Purkinje cell

Which part of the cerebellum is the oldest?

Vestibulocerebellum

Which part of the cerebellum provides information on the body's balance and equilibrium?

Vestibulocerebellum

What is the function of the Purkinje cells in the cerebellum?

To respond to excitatory input from the parallel fibers

What is required for learning to occur in the cerebellum?

Neuroplasticity

What can influence the function of the vestibulocerebellum?

Ethanol and drugs

Which part of the cerebellum is responsible for smooth, coordinated movements of muscles in the distal limbs?

Spinocerebellum

What information does the intermediate zone of the cerebellum receive when a movement is performed?

A and C

What is the function of the cerebellum in relation to movement?

To dampen movements

What effect does cerebellum dysfunction in the spinocerebellum have on arm movements?

It causes the arm to oscillate back and forth past its intended point

Which part of the cerebellum acts as a comparator and compares the intended movement with the actual movement?

Intermediate zone

Where does the intermediate zone of the cerebellum send signals to after comparing the intended movement with the actual movement?

A and B

What must be overcome before a movement can be stopped?

Momentum

What is the term for the effect of cerebellum dysfunction in the spinocerebellum causing the arm to oscillate back and forth past its intended point?

Intention tremor or action tremor

Which part of the cerebellum is responsible for planning, sequencing, and timing complex movements?

Cerebrocerebellum

What is the main function of the premotor area and sensory areas in movement planning?

Provide appropriate motor signals

What is the consequence of damage to small areas of the lateral zones?

Coordination of movements is unaffected

What is dysmetria?

Overshooting and overcompensating movements

Which areas of the cerebellum have the most communication with the premotor area and primary and association somatosensory areas?

Lateral zones

What is the role of the cerebrocerebellum in coordinating patterns such as writing, running, and talking?

Time different movements

What type of dysfunction usually occurs when one or more of the deep cerebellar nuclei are damaged?

Serious dysfunction

What can cause dysmetria and ataxia due to the inability to interpret feedback information from the moving parts of the body?

Lesions in the spinocerebellar tracts

What is the function of the basal ganglia in movement coordination?

Provide appropriate motor signals

Which part of the brain helps to provide extra motor force and stop movements at the intended point?

Cerebellum

What is the main function of the cerebellum in relation to muscle contractions?

Programming muscle contractions in advance

Which of the following is a clinical manifestation of cerebellar lesions within the spinocerebellum?

Dysdiadochokinesia

What is the term for the lack of coordination due to errors in rate, range, force, and direction of movement?

Ataxia

Which of the following is a clinical manifestation of cerebellar lesions within the vestibulocerebellum?

Cerebellar nystagmus

What is the term for the inability to stop a movement?

Rebound phenomenon

What is the function of the cerebellum with the spinal cord?

Enhance the stretch reflex

What is the term for the failure of progression in talking due to the inability to coordinate mouth, larynx, vocal cords, and respiratory system?

Dysarthria

What is the term for the lack of coordination due to errors in rate, range, force, and direction of movement?

Ataxia

What is the term for the inability to perform rapid alternating movements?

Dysdiadochokinesia

Which circuit inhibits skeletal muscle motor activity and results in hypokinetic activity?

Putamen circuit

Which circuit increases skeletal muscle motor activity and results in hyperkinetic activity?

Caudate circuit

Which circuit controls cognition of sequences of motor activity?

Caudate circuit

Which circuit operates in a push-pull manner?

Both circuits

Which circuit is the dominant system?

Putamen circuit

Which system results in lowered motor activity when stimulated?

Putamen circuit

Which disease is an exception to the normal effect of interrupting the indirect pathway?

Parkinson's disease

Which structures make up the dorsal striatum?

Caudate nucleus and putamen

What type of neurons are mainly found in the dorsal striatum?

GABA-producing neurons

Which receptors stimulate the nerves of the direct pathway in the basal ganglia?

D1 receptors

Which receptors inhibit the nerves of the indirect pathway in the basal ganglia?

D2 receptors

Which neurotransmitter pathways go from the cortex to the caudate and putamen?

Acetylcholine pathways

What is the consequence of damage to the putamen circuit or the globus pallidus?

Athetosis

What type of movements are associated with lesions in the subthalamus?

Hemiballismus

What type of movements are associated with multiple lesions in the putamen?

Chorea

What is the effect of cholinergic drugs within the CNS?

Decrease in motor activity

Which neurotransmitter pathways stimulate the indirect pathway in the basal ganglia?

Acetylcholine

Which neurotransmitter is responsible for hyperpolarization or IPSPs in the basal ganglia?

GABA

Which neurotransmitter pathways go from the cortex to the caudate and putamen?

Acetylcholine

What type of signals do glutamate pathways carry in the basal ganglia?

Excitatory

Which areas provide information to the putamen circuit in the basal ganglia?

Prefrontal, premotor, and somatosensory

Where does the output of the putamen circuit in the basal ganglia go to?

Premotor and primary motor cortex

Which areas do the ancillary circuits in the basal ganglia connect to?

Subthalamus and substantia nigra

Which part of the brain is responsible for changing the timing and intensity of movements based on somatosensory information?

Basal ganglia

What is the term for the inability to accurately perceive objects due to lesions in the posterior parietal cortex?

Agnosia

What is the term for the neglect of the left side of the body due to lesions in the right parietal lobe?

Personal neglect syndrome

What is the name of the disease characterized by the loss of dopaminergic neurons or lesions within the substantia nigra?

Parkinson's disease

What are some symptoms of Parkinson's disease caused by the loss of dopaminergic neurons?

Muscle rigidity, dysphagia, speech disorders

What is the term for the feeling of trudging through water or a sense of heaviness experienced by patients with Parkinson's disease?

Bradykinesia

What type of drugs are typically used to treat Parkinson's disease by blocking peripheral metabolism of L-DOPA?

Inhibitors of dopamine decarboxylase

Which syndrome is characterized by the loss of inhibition in CNS circuits, leading to easy oscillation?

Hypokinetic syndrome

What are anticholinergic drugs useful against in Parkinson's disease?

Muscle rigidity and resting tremor

What is the term for the loss of ability to perceive objects accurately through normal functioning sensory inputs?

Agnosia

Which neurotransmitter pathways go from the caudate or putamen to the globus pallidus and substantial nigra?

GABA pathways

Which neurotransmitter pathways go from the substantia nigra to caudate nucleus and putamen?

Dopamine pathway

What is the role of glutamate pathways in the brain?

They balance out inhibitory signals

Study Notes

Motor Cortex

  • The area responsible for controlling muscles in the hand and muscles concerning speech is the ventralateral area of the motor cortex.
  • The motor cortex is responsible for controlling voluntary movements.
  • Somatic signals can increase or decrease muscle contraction.
  • The motor cortex is divided into four areas.

Primary Motor Cortex

  • The primary motor cortex begins in the precentral gyrus.
  • The primary motor cortex is responsible for controlling simple movements.

Premotor Cortex

  • The premotor cortex is responsible for motor imaging and contains mirror neurons.
  • The premotor cortex is located in the precentral gyrus and frontal lobe.

Supplemental Motor Cortex

  • The supplemental motor cortex is located in the superior frontal gyrus and precentral gyrus.
  • The supplemental motor cortex is responsible for controlling bilateral movements such as climbing or grasping an object with both hands.

Broca's Area

  • Broca's area is responsible for motor speech and is located in the inferior frontal gyrus.
  • Damage to Broca's area can result in motor aphasia.

Pyramidal Tracts

  • The pyramidal tracts originate in the primary motor cortex and decussate in the medulla oblongata.
  • The pyramidal tracts include the corticospinal and corticobulbar tracts.

Betz Cells

  • Betz cells are found only in the motor cortex and project down through the spinal cord onto motor neurons.
  • Betz cells are responsible for transmitting signals to the spinal cord.

Red Nucleus

  • The red nucleus is located in the midbrain and is an alternative pathway for transmitting cortical signals to the spinal cord.
  • The red nucleus gives rise to the rubrospinal tract.
  • The rubrospinal tract decussates in the lower brain stem and goes into the lateral columns of the spinal cord.
  • The rubrospinal tract is responsible for transmitting signals to the spinal cord.

Language

  • The lobe of the brain important for language comprehension is the temporal lobe.
  • The area responsible for word formation in language is Broca's area.
  • The area responsible for language comprehension is Wernicke's area.
  • Wernicke's area is located in the posterior superior temporal gyrus.
  • The arcuate fasciculus connects Wernicke's area to Broca's area.

Stroke

  • The most common form of dementia in the United States is Alzheimer's disease.
  • The main cause of ischemic stroke is an occlusion of a cerebral blood vessel resulting in an infarction.
  • The main cause of hemorrhagic stroke is a rupture of a cerebral blood vessel.
  • The middle cerebral artery supplies the largest portion of the left cerebral hemisphere.

Cerebellum

  • The cerebellum is responsible for controlling dynamic balance and eye movements.
  • The cerebellum receives information from the motor cortex and periphery to coordinate movement.
  • The cerebellum helps to plan, sequence, and time complex movements.
  • The vermis is responsible for motor coordination of the axial body, neck, shoulders, and hips.
  • The intermediate zone controls muscle contractions in the upper and lower limbs, and face.
  • The lateral zone joins with the cerebral cortex in overall planning of sequential motor movements.
  • The dorsal spinocerebellar tracts receive proprioceptive signals from muscle spindles and Golgi tendon organs.
  • The ventral spinocerebellar tract receives information from the spinal cord.
  • The cerebellar cortex is responsible for providing anticipatory correction.

Test your knowledge of the motor cortex and its divisions with this quiz. Learn about the primary, premotor, and supplementary areas, as well as their functions in controlling muscles and sending commands to skeletal muscles. Discover how the motor cortex plays a role in stabilizing joints and controlling hand movements and speech.

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