Motor system Flashcards
What are the 3 basic movement types?
Reflexive responses
Rhythmic motor patterns
Voluntary movements
What is the highest level of motor control?
Programming in cerebellum and basal nuclei
What is the middle level of motor control?
Motor cortex - projection areas
What is the lowest level of motor control?
Segmental motor controls in spinal cord
What is a UMN?
Located within brain or brainstem
Axon travel downs spinal cord
Innervates alpha and gamma motor neurons in ventral horn of spinal cord
What is a LMN?
Alpha and gamma motor neurons located in ventral horn of spinal cord
What layer of the cerebral cortex is almost absent in Brodmann’s areas 4 and 6?
Layer 4 - inner granular
What layer of the cerebral cortex are the cell bodies of the corticospinal tract located?
Layer 5
What will electrical stimulation of Brodmann’s area 4 cause?
Movement of an individual or a few muscles
Lowest threshold of movement
Short latency of movment
The cortical region supplying the lower limb is supplied by what artery?
ACA
The cortical region supplying the hand and face is supplied by what artery?
MCA
What occurs with a lesion to the primary motor cortex?
Contralateral paralysis
What occurs with a lesion to the premotor cortex?
Apraxia - inability to perform voluntary movement in the absence of paralysis
What is the 3 complex process of voluntary movements?
Posterior parietal cortex (areas 5 And 7) - identification of target
Supplementary motor cortex (area 6) - plan movement
Primary motor cortex (area 4) - execute movement
Efferents from the motor cortex form what tract?
Corticospinal tract
What parts of the internal capsule do the corticospinal fibers pass through?
Face near genu
Upper limb, trunk, and lower limb in posterior limb
Occlusion of what arteries can cause internal capsule lesions?
Deep branches of MCA
Anterior choroidal A
What part of the midbrain do the corticospinal fibers pass through?
Cerebral peduncle/crus cerebri
What happens to corticospinal fibers in the pons?
The separate into fascicles in ventral pons
What happens to the corticospinal fibers in the medulla?
Forms pyramids of anterior medulla
Most fibers decussate
What forms the lateral corticospinal tract in the spinal cord?
Crossed corticospinal fibers from medulla
What forms the anterior corticospinal tract in the spinal cord?
Uncrossed corticospinal fibers from medulla
What tract acts on the lateral motor nuclei of ventral horn of spinal cord?
Lateral corticospinal tract
What tract acts on the medial motor nuclei of the ventral horn of the spinal cord?
Anterior corticospinal tract
What can corticospinal axons synapse with in the spinal cord?
Alpha motor neurons - extrafusal muscle fibers
Gamma motor neurons - intrafusal muscle fibers to muscle spindles
Intrasegmental interneurons - project within same segment
Intersegmental interneurons - ascend and descend to different segmental levels
What is the effect of the corticospinal tract on flexor motor neurons?
Facilitatory/excitatory
What is the effect of the corticospinal tract on extensor motor neurons?
Inhibitory
What are the major UMN tracts?
Corticospinal tract
Corticobulbar tract
Rubrospinal tract
Tectospinal tract
Anti-gravity reflex
Lateral vestibulospinal tract
Pontine reticulospinal tract
Medullary reticulospinal tract
What tracts are part of the anti-gravity reflex?
Lateral vestibulospinal tract
Pontine reticulospinal tract
Medullary reticulospinal tract
Where does the rubrospinal tract terminate?
Anterior gray column of spinal cord
Where is the rubrospinal tract located in the spinal cord?
Lateral white column
What is the function of the rubrospinal tract?
Facilitates the activity of the flexor muscles and inhibits the activity of the extensor muscles
Allows for proximal limb flexion
Where is the tectospinal tract located in the spinal cord?
Anterior white column, close to anterior median fissure
What nuclei in the brainstem are related to the anti-gravity reflex?
Lateral vestibular nucleus
Reticularis pontis oralis
Reticularis pontis caudalis
Reticularis gigantocellularis
Where do fibers of the corticobulbar pathway terminate?
Directly onto neurons of CN V, VII, and XII
Both contralateral and bilateral
When will the eyes go to the side of paralysis?
If lesion is in the FEF and CS
When will eyes go to the opposite side of lesion
When will eyes go to the opposite side of paralysis?
If lesion is in the PPRF and CS
What is decorticate regidity?
Lesion above the red nucleus, possibly from bleeding in internal capsule
Pt is paralyzed
Responds to stimulus by flexion of UL and extension of LL
What is decerebrate rigidity?
Site of lesion in superior and inferior colliculi, below red nucleus
Extensive extensor posture of all extremities
