Motor system III Flashcards
Which part of brain causes the execution of movements?
primary motor cortex
(although almost all cortical areas input)
These cells are from which motor tract? [1]
Primary motor cortex –> corticospinal tract
Define hemiplagia [1]
loss of voluntary movements on the contralateral side of the body
What makes a region a watershed region in the brain? [1]
Region supplied by both the MCA and ACA: means that if stroke occurs can compensate
Which artery supplies most of the lateral surface of the frontal, parietal and temporal lobes? [1]
MCA
Which arteries do the arrows point to? [1]
Lenticulostiate arteries
Label 5, 6 & 7
1 - superior temporal gyrus;
2 - inferior frontal gyrus; 3 - insular cortex;
4 - temporal stem;
5 - internal capsule;
6 - thalamus;
7 - lentiform nucleus (the internal and external globus pallidus and the putamen)
8 - frontal horn;
9 - superior circular sulcus;
10 - inferior circular sulcus.
The MCA is divided into different segments. Label A-C that depicts this.
A: M1: horizontal section
B: M3: cortical section
C: Sylvian section
Middle cerebral artery:
Describe the difference between an occlusion in M1 v M3
M1: supplies blood supply to the basal ganglia via the lenticulostriate arteries & motor cortex. Causes a very bad lesion
M3: Only supplies motor cortex alone - Less bad lesion
Which part of the body would an occlusion to the MCA not effect and why? [2]
Lower limbs are not affected: supplied by ACA
How is the the somatosensory cortex involved in motor control?
40% of corticospinal and corticobulbar tract axons arise from somatosensory cortex; can modulate somatosensory input (e.g. supress nocicpetive pain)
FYI summary
Where does the corticospinal tract cross decussate in the body? [1]
On the way to the brainstem, which structure does the cortiospinal tract pass through? [1]
Decussates in upper spinal cord: C1-C5
Goes through the internal capsule on way to brainstem
Describe an overview of the corticospinal tract [3]
- Primary motor cortex on l/r signal: upper motor neuron travels in brain to medulla where the lateral corticospinal tract decussates; the ventral corticospinal tract will decussate in the spinal cord just before they synapse with lower motor neurons.
- The lateral corticospinal tract controls distal fine muscle movement.
- The ventral corticospinal tract controls axial movement
- After synapsing at the ventral horn, becomes lower motor neuron. leaves spinal cord to innervate muscle motor
The corticobulbar tracts provide innervation to the musculature of which region of the body?
Head and neck
Upper limbs
Lower limbs
Neck
The corticobulbar tracts provide innervation to the musculature of which region of the body?
Head and neck
Upper limbs
Lower limbs
Neck
Extrapyramidal tracts:
Desribe the path of the medial and lateral reticulospinal tracts [2]
Medial Reticulospinal Tract (Pontine): Descends ipsilaterally
Lateral Reticulospinal tracts (Medullary): Descends bilaterally
Extrapyramidal tracts:
Desribe the path of the medial and lateral reticulospinal tracts [2]
Medial Reticulospinal Tract (Pontine): Descends ipsilaterally
Lateral Reticulospinal tracts (Medullary): Descends bilaterally
Extrapyramidal tracts:
Describe the course of the lateral vestibulospinal tract
Fibres descend ipsilaterally though the anterior funiculus of the same side of the spinal cord, synapsing on the extensor antigravity motor neurons
Describe the function and path of the rubrospinal tract [2]
Function: Controls muscle tone in flexor muscle groups; Inhibits extensor tone
Path:
- Arises from the red nucleus in the brainstem
- crosses at medulla
- terminates primarily in the cervical and thoracic portions of the spinal cord
Path and function of tectospinal tract? [2]
Coordinates voluntary head and eye movements
Involved in both auditory and visual cues, it is primarily understood to orient our eyes and head towards both auditory and visual stimuli. For example, if you were sitting in a quiet room and all of a sudden heard a noise to your right, you would subconsciously turn your head in that direction and orient your eyes towards the direction of the sound, attempting to find the source.
Path:
Originates in the superior colliculus
Projects to the contralateral cervical spinal cord to terminate in Rexed laminae VI, VII, and VIII
Describe the how a patient would present with:
Decorticate posturing [4]
Decerebrate posturing [3]
Decorticate posturing:
* plantar flexed
* internally rotated legs
* flexed hands and elbows
* adducted arms
Decerebrate posturing:
* Plantar flexed
* Pronated hands
* Extended arms
