6 - Motor system 2 Flashcards
What part of the internal capsule contains the corticobulbar tracts?
Genu of internal capsule
What area of the internal capsule contains the motor fibres to the head and neck?
Genu of internal capsule
Name the pyramidal fibres which supply the head and neck:
Corticobulbar tracts
Where do the corticobulbar tracts terminate?
Cranial nerve nuclei in the brainstem
Describe the course of the corticobulbar tract:
- Fibres originate from cerebral cortex
- Through corona radiata
- Through genu of internal capsule
- Terminate on both left and right CN nuclei in brainstem (except CN VII, XII)
Name the pyramidal fibres which supply the body:
Corticospinal tracts
Which areas of the cerebral cortex do the pyramidal tracts arise from?
- Motor cortex (pre-central gyrus)
- Premotor cortex
- Supplementary motor area
- Somatosensory cortex
The internal capsule is closely associated with which major artery?
Middle cerebral artery
What is the blood supply to the internal capsule?
Lenticulostriate arteries
Describe the route of the lateral corticospinal tracts:
- Fibres originate from cerebral cortex
- Through corona radiata
- Through posterior limb of the internal capsule
- Through crus cerebri of cerebral peduncles in midbrain
- Decussate just below pyramids of medulla
- Descend contralaterally in lateral white matter of spinal cord
What is the role of the lateral corticospinal tracts?
Voluntary control of the muscles of the limbs
What is the blood supply to the corticospinal tracts in the spinal cord?
Anterior spinal artery
Describe the route of the anterior corticospinal tracts:
- Fibres originate from cerebral cortex
- Through corona radiata
- Through posterior limb of the internal capsule
- Through crus cerebri of cerebral peduncles in midbrain
- Descend ipsilaterally in anterior white matter of spinal cord
- Decussate at exit level of spinal cord
What is the role of the anterior corticospinal tracts?
Voluntary control of the muscles of the trunk
Explain forehead sparing in stroke:
- Stroke is usually a lesion in one hemisphere
- Facial nerve nuclei supplying the upper half of the face receive innervation from both hemispheres
- Therefore can still control all muscles of forehead, even though unilateral UMN lesion
