Motor Systems Flashcards
Where is the primary motor cortex located?
Immediately in front of the central sulcus (area 4)
What happens if there is a lesion in the brain just in front of the central sulcus?
This affects the primary motor cortex (Area 4) and leads to paralysis or paresis of specific muscle groups
What happens if there is damage to the premotor cortex and/or supplementary motor cortex?
Leads to apraxia (inability to perform purposeful actions) but contralateral side may be able to take over to compensate to minimise symptoms
Where are the frontal eye fields located?
In the anterior cerebrum (temporal lobe)
What is the function of the frontal eye fields?
Controls of extra ocular eye muscles
What are the consequences of bilateral lesions of the frontal eye fields?
Oculomotor apraxia (difficulty moving eyes horizontally or following an object)
Where is Broca’s area located?
Adjacent to the promote cortex in the frontal lobe
What is the function of Broca’s area?
Motor to muscles regulating speech
What happens if there is damage to Broca’s area?
Motor aphasia (difficulty verbalising strings of words e.g. complex sentences)
What is the function of the dorsolateral prefrontal cortex (most anterior portion of frontal lobe)
Planning movement and executive functions
What is the consequence of lesions to the dorsolateral prefrontal cortex?
Apathy, personality changes, and an inability to sequence tasks
What is the function of the orbitofrontal cortex?
Controls/inhibits motor responses associated with the limbic system such as hunger, thirst, sexual drive etc.
What is the consequence of a stroke in the proximal middle cerebral artery?
There is loss to all of one side of the frontal lobe as well as blocking of blood supply to the basal ganglia from the lenticulostriate arteries, so this is far more debilitating than a distal MCA occlusion
Which artery supplies the motor cortex portion to the lower limbs?
Anterior cerebral artery
What is the red nucleus?
A large, round nucleus in the midbrain next to the oculomotor nuclei that carries the corticobulbar tract
What is the corticobulbospinal tract?
A tract which passes through the internal capsule on its way to the brainstem and is made up of the corticobulbar and corticospinal portions
Describe the corticobulbar aspect of the corticobulbospinal tract
This tract terminates on various cranial nerve nuclei to the muscles of head/neck as well as the pontine nuclei, reticular formation and red nucleus
Describe the corticospinal aspect of the corticobulbospinal tract
This tract continues after termination of the corticobulbar tract into the lower medulla and decussates to form the lateral and medial corticospinal tracts
What happens if there is damage to the corticospinal tract in the spinal tract?
Loss of control of certain muscles but not a loss of posture and gait ordinarily
What is the tectospinal tract?
Coordinates voluntary head and eye movements: originates in the superior colliculus and projects to the contralateral cervical spinal cord
What is the medial vestibulospinal tract?
Mediates involuntary coordination of the head and neck muscles with the extra ocular eye muscles
Describe the lateral vestibulospinal tract
Projects from the vestibular nuclei (between medulla and pons) and projects ipsilaterally to antigravity muscles to control posture and balance
Describe the reticulospinal tract
Arises in the reticular formation (pons/medulla) and projects bilaterally down the spinal cord to provide general arousal
Describe the rubrospinal tract
Arises in the red nucleus of the midbrain and carries cerebellar commands to the spinal cord
