Lecture 11: Motor Systems Flashcards
Distinguish between direct and indirect corticobulbar fiber
Direct: fibers that project to cranial motor neurons
Indirect: fibers that project to midbrain and pontine reticular formations adjacent to CN nuclei
Where are axons terminating in upper spinal cord levels vs. lower spinal cord levels located in the posterior limb of the internal capsule?
- Axons terminating in upper spinal cord levels are rostral
- Axons terminating in lower levels are caudal
The Supplementary Motor Cortex is in which Brodmann’s area and is involved in what function?
- Medial portion of Area 6
- Involved in organizing or planning the sequence of muscle activation required to make a movement
- M1 will be the one executing the movement
The Premotor Cortex is located in what Broadmann’s area and is closely associated with what other cortex?
- Area 6
- Closely associated with Supplementary Cortex
Premotor cortex receives inputs from where and projects to which areas?
- Receives inputs from sensory areas of the parietal lobe
- Projects to M1, the SC, and RAS
The Premotor cortex is involved with what function of movement?
- The PREPARATION to move
- Organizes those postural adjustments required to produce movement
- Directs control of proximal limb muscles use to position the arm for movement tasks or to orietn the body for movement
What artery may contribute to the catastrophic lesions of the posterior limb of the internal capsule and what deficits will occur?
- Lenticulostriate branches of the M1 segment of the MCA
- Motor symptoms in the contralateral UE and LE’s = weakness and transient flaccid paralysis
- Followed by spastic paralysis (UMN signs) that typically never resolve
What makes up the striatum?
Caudate + Putamen + Nucleus Accumbens + Olfactory Tubercle
What 3 things make up the Corpus Striatum?
Globus pallidus + Caudate + Putamen
What 2 things make up the Lentricular nucleus?
Globus pallidus + Putamen
What 2 things make up the neostriatum?
Caudate + Putamen
What is the Subthalamic Fasciculus (Basal Nuclei Tract); what type of fibers?
- Reciprocal fiber tracts between globus pallidus and subthalamus
- Contain excitatory fibers
What are the Nigro-Thalamic Fibers (Basal Nuclei Tract); where do they terminate and is it the same area as the fibers from globus pallidus?
- Non-dopaminergic fibers that originate in pars reticularis of substantia nigra
- Terminate in VA and VL thalamic nuclei
*Fibers from the globus pallidus and the substantia nigra DO NOT terminate in the same areas of the VL and VA thalamic nuclei
What are the Nigro-striatal fibers (Basal Nuclei tracts); where do they terminate and what disease are they related to?
- Dopaminergic fibers that originate in pars compacta of substantia nigra
- Terminate in the caudate and putamen
- Neurons in this area of the substantia nigra are destroyed in Parkinson’s disease
Neurons in which area are destroyed in Parkinson’s disease?
Dopaminergic fibers that originate in pars compacta of the Substantia Nigra
What are the Striatonigral fibers (Basal Nuclei tract); what disease are they related to?
- GABAergic fibers (INHIBITORY) originate in putamen
- Terminate in the pars compact of the substantia nigra and medial/lateral segments (GP)
- Thought to contribute to Huntington’s disease
Huntington’s disease is caused by loss of what type of neurons; typically recognized on imaging as atrophy where?
- Loss of INHIBITORY GABAergic neurons of the basal ganglia (Striatonigral fibers)
- Atrophy of the caudate nucleus with concomitant enlargement of the frontal horns of the lateral ventricles
What is Syndenham’s Chorea (cause and presentation)?
- Childhood autoimmune disease
- Major manifestation of rheumatic fever (infection with group Aβ-hemolytic streptococci)
- Present with rapid, irregular, aimless movements of the limbs, face, and trunk.
What is Ballismus, how does it present, and what causes it?
- Most typically presents as hemiballismus
- Uncontrolled flinging (ballistic) movements of limb
- Common with vascular lesions localized to contralateral SUBTHALAMIC NUCLEUS or SUBTHALAMIC FASCICULUS
What is Chorea, how does it present, and what causes it?
- Rapid, irregular, involuntary, dance-like movements that flow randomly from one body region to another
- Characteristic of Huntington disease, but may occur as side effect of treatment in Parkinson disease
- Loss of neurons in indirect pathway
What is Athetosis, how does it present, and how is it classified when the movements are more brisk and when more intense?
- Continous writhing of distal portions of one or more extremities
- Slow, sinous, and writhing movements more obvious in the UE and hands/face
- When more brisk and resemble chorea —> choreoathetosis
- When more intense, sustained, and resemble dystonia —> athetotic dystonia
Corticonuclear fibers consist of UMN’s that influence which nuclei of CN’s?
- Motor nuclei of CN V, VII, XII
- Nucleus Ambiguus of CN IX and X
- Accessory nucleus of CN XI
The nucleus accumbens and olfactory tubercle comprise what structure that links the amygdala and hippocampus to the dorsalmedial nucleus of the thalamus and the globus pallidus; what role does this nucleus have in movement?
- Comprise the Ventral Striatum
- Nucleus accumbens plays a role in the motivational and emotional aspects of movements
What are the motor nuclei of the thalamus?
Ventral anterior and Ventral lateral nuclei
