Motor Systems ll Flashcards
Corticospinal and corticobulbar axons
descend from cortex as the: (4)
- Corona radiata (axons streaming from
cortex) - Internal capsule (at level of basal
ganglia) - Cerebral peduncles (at level of
midbrain) - Pyramidal tract (at level of medulla)
What consists the indirect (extrapyramidal) pathway?
Consists of cortical and brainstem
projections that have many synaptic
connections before reaching spinal cord
motor neurons.
What is the indirect (extrapyramidal) pathway controlled by? (2)
-Basal Ganglia (i.e., caudate, putamen,
globus pallidus)
–Cerebellum
What makes the basal ganglia a complex circuitry? (5)
- Reciprocal connections to cortex
- Reciprocal connections to substantia
nigra - Projections to thalamus
- Output to brainstem & spinal cord
- Modulates activity in direct pathway
The basal ganglia has ______________ and __________________ pathways.
Excitatory and inhibitory pathways
What are the functions of the basial ganglia? (2)
Functions in controlling & coordinating
movement patterns for large groups of
muscles
Damage to the basal ganglia can result in? (2)
–hypokinetic symptoms (e.g.,
Parkinson’s disease)
–hyperkinetic symptoms (e.g.,
Huntington’s disease)
What is the role of the cerebellum?
Involved in movement coordination (i.e.,
timing, accuracy), motor learning, balance
Where does the cerebellum receives sensory input from? (3)
spinal cord
(spinocerebellar pathways), brain stem &
cortex
The cerebellum provides output (indirectly) to ____________________
spinal motor neurons
What in the cerebellum allows it to adjust movements to match intentions?
- Feedback circuit
Organization of the cerebellum: Contains about ______ of all the neurons in he entire central nervous system
half
Organization of the cerebellum: Divided into ___________________ with multiple __________
Two hemispheres
Lobes
Organization of the cerebellum: __________ projects from the _______________ (eye movements, balance)
Flocculus
Ventral Surface
Organization of the cerebellum:___________ protrudes along dorsal midline (termination site of spinocerebellar pathways)
Vermis
Characteristics of Lower motor neurons (LMN) (4)
- PNS
- Originate in brainstem as cranial nerves
- Originate in spinal cord as spinal nerves
- Terminate at muscles
Characteristics of Upper motor neurons (UMN) (4)
- CNS
- Originate in cortex and terminate in brain stem
(corticobulbar tract) or spinal cord (corticospinal tract) - Pyramidal system (CB & CS tracts) directly controls
LMN’s - Extrapyramidal system influences pyramidal system &
therefore indirectly controls LMN’s
