Descending tracts (big ppt) Flashcards
Where are the pyramidal tracts?
Originate in the cerebral cortex and carry motor fibres to spinal cord and brainstem
What are the pyramidal tracts responsible for?
Voluntary control of musculature
Where are the extrapyramidal tracts?
They originate in the brain stem and carry motor fibres to spinal cord
What are the extrapyramidal tracts responsible for?
Involuntary and autonomic control of musculature
Where do the corticospinal tracts originate?
In the cerebral cortex
What are the inputs to the corticospinal tracts?
Primary motor cortex, premotor cortex and supplementary cortex
What is the pathway of the corticospinal tract?
- Cortex
- Descends through the internal capsule
- Crus cerebri
- Pons
- Medulla
- In the caudal part of the medulla the tract divides into 2
Where does the lateral corticospinal tract terminate?
Decussates and then descends, terminating in ventral horn
Where does the anterior corticospinal tract terminate after decussating?
Anterior corticospinal tract remains ipsilateral to the spinal cord, then decussates and terminates in the ventral horn of the upper thoracic levels
Where does the corticobulbar tracts begin?
In the lateral aspect of the primary motor cortex
What is the pathway of the corticobulbar tract?
- Cortex
- Descend through internal capsule
- Crus cerebri
- Brainstem
- Terminate on the motor nuclei of cranial nerves (acting on facial and neck muscles)
How do the fibres innervate the motor neurons in the corticobulbar tract?
Bilaterally
Except: facial nerve and hypoglossal nerve
What type of innervation does the facial nerve have?
Contralateral innervation
- Only affects muscles in lower quadrant of the face (below the eyes)
What type of innervation does the hypoglossal nerve have?
Only provides contralateral innervation
Where do the extrapyramidal tracts originate?
In the brainstem
- there is 4 in total
