Voluntary Control Of Muscles Flashcards
What are the two methods used to classify somatic motor pathways?
Pyramidal tracts(corticospinal tracts)
Extrapyrimidal tracts
What are the corticospinal tracts?
3/4 of fibers decussate in the medulla and move down the cord in the crossed corticospinal tract located on the opposite side of the spinal cord in the lateral white column and the 1/4 don’t deccussate but move down the same side of the SC as the cerebral area which they cane from
What is the Extrapyramidal tract?
They consist of all motor tracts from the brain to the SC anterior horn motor neurons except the pyramidal tracts
What does the direct descending spinal pathway?
Controls muscle tone and conscious skilled movements
Direct synapse of UMNs of the cerebral cortex with the LMNs in the brain stem or SC
The tracts are the
Corticospinal
Lateral
Anterior corticobulbar
What is the indirect descending spinal pathway?
Synapse in some intermediate nucleus rather than directly with LMNs
The tracts are the rubrospinal
Vestibulospinal
Reticulospinal
Tectospinal
What are upper motor neurons?
Where the cell body lies in the CNS and the UMNs synapses on the Lower and innervates a single motor unit in a skeletal muscle
What is the lower motor neuron?
The cell bodies of the LMN lies in the nucleus of the brain stem or SC and triggers a contraction in innvervated muscle and only axon of lmns extends outside CNS
And damage to the LMN eliminates voluntary and reflex control over innervated motor unit
Where does control of skeletal muscles come from?
Corticospinal
Medial
Lateral pathway
What is the corticospinal pathway?
Called the pyramidal system
Provides voluntary control over skeletal muscles and begins at the pyramidal cells of the primary motor cortex and the axons of these UMN move down into the brain stem and SC and synapse into the LMN that control skeletal muscles
What 3 tracts does the corticospinal pathway contain?
Corticobulbar -move eye,jaw and some muscles of the neck
Lateral and Anterior corticospinal tracts
What are the corticospinal tracts?
The axons synapse on LMN in the anterior gray horn of SC and move down the lateral tracts which are visible along the ventral surface of the medulla as pyramids
The axons in the anterior tracts cross over to opposite side of SC in the anterior commisure before synapsing on LMN in anterior gray horns
What are the medial and lateral pathways?
Components of the medial pathway help control gross movements of trunk and proximal limb muscles
Components of lateral pathway help control distal limb muscles that perform more precise movements
What is the medial pathway?
Control muscle tone and gross movements of neck trunk and proximal limbs
Where are the UMN of the medial pathway located in?
Vestibular nuclei
Superior and inferior coniculi
Reticulated formation
What is the vestibular nuclei?
Recieves Information over the VII from receptors in the inner ear that monitor and movement of head
It is to maintain posture and balance
The descending fibers of SC are the vestibukospinal tracts
