Motor cortex and motor pathways Flashcards
What is the primary motor area responsible for
Initiation of voluntary motor activity
What is the premotor area responsible for
Storing programs for learned motor activities
Where are the Frontal eye fields located
In the prefrontal cortex, considered part of the oculomotor system
What is the role of frontal eye fields
Stimulates saccadic (quick, simultaneous) eye movements–> need this to allow both eyes to move separately/together
Role of vestibulospinal tract
Send info from inner ear to monitor position of head
vestibular nuclei responds by altering muscle tone, neck contraction and limbs for posture and balance
Role of tectospinal tract
Send info to the head, neck and upper limbs in response to bright and sudden movements and loud noises
What does tectum area consist of
Superior colliculi–> recieves visual info
Inferior colliculi–> recieves auditory info
Role of Reticulospinal Tract
Sends info to cause eye movements and activate respiratory muscles
Role of Rubrospinal Tract
Sends info to flexor and extensor muscles
How many synapses does the corticospinal tract have
It is monosynatic (only upper and lower motor neuron)
Role of corticospinal tract
Primarily voluntary motor function
Axons arising from the parietal lobe modulate transmission of sensory signals to brain by synapsing with DCS
How many fibres of corticospinal tract decussate
85-90% fibres
Where do these fibres of corticospinal tract cross
At pyramidal decussation in medulla oblongata
What tract do the crossed fibres of corticospinal tract form?
Lateral Corticospinal tract
What tract do the uncrossed fibres of corticospinal tract form?
Ventral corticospinal tract
What is the lateral corticospinal tract responsible for
Responsible for skilled volitional movement (primarily of limbs)
Conscious control over skeletal muscles
Modulates transmission of sensory input via ascending sensory pathways
Where does the ventral corticospinal tract cross?
Decussates at the level of SC in ventral white comissure
What is the vnetral conrticospinal tract responsible for?
Primarily concerned with the conscious control of axial (trunk) muscle
Conscious control over skeletal muscles
Explain the path of the corticospinal tract from the motor cortex to where it decussates at the pyramids
Axons from cerebral cortex
Transverse subcortical white matter and posterior lib of internal capsule
Brainstem:
-Basis pedunculi (cerebral pudenculi) of midbrain
-Small fibres enter pons
-Pyramids of medulla oblongata
Where do most fibres terminate of the corticospinal tract
At intermediate gray matter and Ventral horn of SC
Some fibres that originate from the parietal lobe, terminate in the dorsal horn SC
Where does the LMN synapse with the UMN
In ventral root and then leaves SC
What is the corticobulbar tract responsible for
Conscious control over eye, jaw and face muscles
Carries motor input important for swallowing and speech
How is the Corticospinal tract formed
Arises from the lateral aspect of primary motor cortex
Fibres converge and pass through the internal capsule to the brainstem
Some fibres/corticospinal tract synapse with cranial nerves
Neurons terminate on the motor nuclei of cranial nerves
What is a lesion cranial nerve nuclei called?
Bulbar lesion–> “bulbar palsy”
What are lesions to axons of CNS called
Peripheral nerve lesion
What is the final common pathway
Motor neurons from the ventral horn of the SC that project to the effectors for action
This includes motor nuclei of CNS
