Motor Pathways Flashcards
What is meant by the term motor-system heirachy?
Explain the principle
- Several systems with different tasks are involved in a movement
- The tasks in each system are differently complex going from high complexity = high heirachy (Motor cortex) to low complexity = low heirachy (e.g. corticospinal tract)
Where is the primary motor cortex located?
It is located just anteriorly to the central sulcus
What is the function of the primary motor cortex?
It controls + initiates voluntary fine, discrete and precise movements
–> Sends out signals to decending tracts to execute movements
Explain the somatotopic organisation in the primary motor cortex
It looks like a homunculus upside down: feet + legs are more medially, face is more laterally
Explain the route of the Lateral corticospinal tract
- Neurons emerge from primary motor cortex
- Run down brain in internal capsule
- Decussate in the Medulla
- Run down in contralateral corticospinal tract
- Leave the corticospinal tract at level of inntervation + enter the anterior horn
- Synapse in the anterior horn onto lower motor neuron
Explain the route of hte anterior corticospinal tract
- Originate in primary motor cortex
- Run dowin in internal capsule
- enter the medulla on ipsilateral side
- Enter the anterior corticospinal tract at ipsilateral side
- Leave the anterior cortiocospinal tract and Decussate at level of insertion
- Synapse in the Anterior Horn onto 2nd order neurons
What is the function of the corticospinal tracts?
They convey voluntary movement to the
- Anterior corticospinal tract
- Axial muscles (neck movement and thoracic muscles, intercostal muscles)
- Lateral corticospinal tract
- the rest of the body
What is a corticobulbar pathway?
Pathways for motor neurons of cranial nerves
Explain the Corticobulbar tract
- Emerge from head reagion in primary motor cortex
- Travel in internal capsule
- Synapse in nucleus of cranial nerve in brainstem
- Emerge as cranial nerves
Where is the premotor cortex located?
Anterolaterally to the primary motor cortex
What is the function of the premotor cortex?
Planning of movement, requires:
- Knowledge + understanding the intra-personal space (where musces/body parts are in relation to one another)
- Knowlledge of extrapersonal space –> Where the body is in relation to the environment
Where is the Supplementory Motor area located?
Anteromedially to the primary motor cortex
What is the function of the supplementary motor cortex?
- Planning of complex movements and + sequencing movements
- Regulation of internal movements (e.g. speech)
–> area that is active when thinking about a movement
What is the Association cortex?
Which parts are involved in it and what is their function?
Area of the brain that do play a role in movement but not directly involved in output etc
-
Posterior parietal cortex
- Motor learning + planning–> movements are accurately targeted in external space
- Prefrontal cortex
- Selection of appropriate movements
- adds personality to movements –> when having touched a hot plate before you are not likely to do it again
What is a lowe motor neuron?
Motor neuron after synapse
In spinal chord, Brain stem
What is an upper motor neuron?
Motor neuron before synapsing
In corticospinal/corticobulbar tracts
What does pyramidal in relation to motor pathways mean?
Referes to the Lateral corticospinal tract
What does Extrapyramidal in relation to motor function mean?
Basal ganglia, cerebellum
Paresis
Graded wekness of muscle
Paralysis /Plegia
complete loss of muscle activity
Spacticity
increased muscle tone
Hyper-reflexia
exaggerated reflexes
Clonus
abnormal oscillatory muscle contraction
What is…?
Graded wekness of muscle
Paresis
What is…?
complete loss of muscle activity
Paralysis /Plegia
What is…?
increased muscle tone
Spacticity