cortiospinal tract

Question 1

Corticospinal tract

Answer 1

• The major neuronal pathway providing voluntary motor function
• This tract connects axons to carry this information from the cortex to the spinal cord to enable movement

Question 2

Pathway of the cct

Answer 2

• The CCT Starts in the cortex where Upper motor neurons are sent down through the cerebral cortex through the brain stem and synapse on cell bodies located in the spinal cord.
• These axons then come out of the spinal tract ( lower motor neuron) and innovate a skeletal muscle.
• As these fibres go down the spinal tract, the fibres can go out into different cranial nerves.

Question 3

What four areas help to control the motor movement of descending fibres

Answer 3

1. The primary motor cortex is when voluntary movement comes from.
2. Pre motor cortex, associated with repeated learned motor movements. Both of these have descending axons.
3. Supplemental motor area, associated with motor movements
4. Primary somatosensory cortex, most of the motor fibres come from this area

Question 4

How do we know when the fibres need to move down?

Answer 4

• The prefrontal cortex ( located in the frontal cortex), this is where the thought comes from e.g. wanting to flex your bicep.
• The prefrontal cortex sends signals to different motor areas to stimulate their descending fibres.
• The basal nuclei in the cerebrum receives this information and adapts it to provide the right level of force for example for the movement.
• The cerebellum also communicates with the cerebral cortex to ensure homeostasis and sends back to the cerebral cortex.

Question 5

Neuromuscular junction

Answer 5

• For a neuron to cross from pre-synapse to post synapse an action potential must travel down the neuron causing depolarization.
• This causes there to be a charge change which will force sodium channels to open
• Sodium then diffuses into the cell causing a positive charge opening calcium gated channels causing an influx of calcium.
• Calcium cases the neurotransmitters to bind with the vesicles on the presynaptic neuron.
• These vesicles release the neurotransmitters over the synaptic cleft and bind to specific receptors on the post-synaptic neuron.
• These receptors open sodium channels to open, sodium enters the cell
• Travels to t-tubules
• Sodium depolarises and causes the sarcoplasmic reticulum to release calcium
• Calcium is needed for muscle contraction as well as ATP

Question 6

What does the lateral corticospinal tracts cause

Answer 6

Lateral corticospinal tracts
- Coming from the motor cortex
- Fine motor skills e.g. drawing = signal for the lateral corticospinal tract
- If moving right hand, it comes from the left hemisphere and crosses at the medulla