Descending Motor Pathways Flashcards
one nerve communicating to the next - comes down from cortex and when gets to sc synapses on one neuron and then goes out to create an action
monosynaptic
comes down and synapses in grey matter on interneuron which then will synapse onto the cell that sends the info out to create the action
interneurons
the pathway that comes out of sc to the final destination - the final path
lower motor neurons
what type of lesion do we see if it is in the LMN?
ispilaterally symptoms
because it stays on that side and has already crossed over in the body since it is in the periphery
stab wound severs dorsal root and neuron = loss of motor and sensory function
these lesions show muscles involved individually and patterns of associated sensory loss follow dermatome patterns
LMN
These lesions result in muscles being affected in groups, an entire extremity or even half of the body (associated sensory loss does not follow dermatome patterns)
UMN
Descending motor pathways from the cortex and brainstem to the spinal cord
Upper motor neurons
what type of symptoms do we see with UMN?
happens before the crossing over so the symptoms we see are usually contralateral
stroke in M1 of area in the arm in the left hemisphere, will have a contralateral issue with my left arm
what is the largest and clinically important descending motor tract
corticospinal tract (pyramidal tract)
what is the function of corticospinal tract (pyramidal tract)
voluntary and fine motor skilled
talk, chew, write, type, sew, = skilled movements of muscles that we need them to do
what is the dorsal horn composed of
lamina I-VI (Projection neurons receiving synapses from primary afferent axons from the dorsal root –somatic and visceral sensory information– and interneurons)
Lamina VII is the intermediate zone (containing autonomic neurons),
what is the ventral horn composed of
Lamina VIII (containing interneurons associated with motor reflexes) and
IX (motor neurons leaving the CNS—not one discrete “ribbon”, but multiple locations in the ventral horn).
Lamina X surrounds the central canal and contains cells important for the perception of visceral pain
function of the rubrospinal tract
Control of dextrous movement
of the upper extremity (mediation of skilled voluntary movements)
describe the reticulospinal tracts
Participating in the control of movement
*Connecting to the spinal cord and cerebellum
*From Nolte text “The reticulospinal tracts are a major alternate route (to the pyramidal tract) by which spinal motor neurons are controlled, both influencing motor neurons directly and regulating the sensitivity of spinal reflex arcs.”
The anterolateral system (also called the Lateral Spinothalamic Tract) of the spinal cord…
is an ascending somatosensory pathway carrying information regarding pain and thermal sensations.