Cortex & Movement Flashcards
What are the predominate neurotransmitters for LMN and UMN?
LMN: ACh
UMN: glutamate
What are the major cortical UMN tracts?
Corticospinal to spinal nerve LMN, corticobulbar to cranial nerve LMN
What are the brainstem UMNs?
Eye movement: sup colliculus vergence center
Vestibular nuclei, red nucleus, reticular formation nuclei
What are the 2 cortical UMN areas?
Primary motor cortex for focal m contractions, and premotor cortex for planning/sequencing of patterned movements
Describe modulation of the primary motor cortex.
Premotor cortex to plan, somatosensory cortex to integrate, thalamus VPM/VPL somatosensory and VL/VA motor
What is motor apraxia?
Lesion to premotor cortex or parietal lobe, inability to perform a planned movement w/o paralysis or ataxia
What are the neurons of empathy?
Mirror neurons in premotor cortex
What are the 2 modulators of motor thalamus?
Basal nuclei (internal globus pallid us, ipsilateral) and pontocerebellum (coordinating intended movement; contralateral)
What are the locations and functions of lateral and medial premotor cortex?
Lat: planning/sequencing of grasping movements, front precentral gyrus, visual/verbal guide
Med: supp motor area, planning/sequencing of complex movements, bilateral effects, post-medial part sup frontal gyrus
Where does corticobulbar tract project?
Non-ocular CN LMNs bilaterally. There are no cortical UMN projections to ocular CN motor nuclei.
What are symptoms of unilateral UMN lesions?
Little effect on LMN of CN 5, 9, 10, 12. For 7: paralysis of contra lower face, forehead spared
What are LMN signs?
Ipsilateral deficit, atonia, atrophy, areflexia, fasciculations
What are UMN signs?
Positive: spasticity, clasped knife, hyperreflexia, Babinski, clonus, pronator drift, no muscle wasting
Negative: weakness/paralysis, loss of dexterity
What is the underlying cause of spasticity?
Exaggerated m spindle stretch reflexes because of abnormal alpha-gamma activation
What are three proposed mechanisms leading to spasticity?
Loss gamma/alpha neuron inhibition, unopposed action certain brainstem pathways, maladaptive remodeling in cord or brain
What is the lentiform nucleus?
Putamen and globus pallidus
Where in the posterior limb internal capsule are corticobulbar, corticospinal, and thalamocortical fibers located?
Bulb: near genu
Spine: posteriorly
TC: face near genu, body posteriorly
What part of the crus cerebra is corticospinal and corticobulbar tracts? What’s in the other parts?
Middle 3/5
Anterior 1/5: corticopontine fibers from anterior cortex
Posterior/lateral 1/5: corticopontine from posterior cortex
What are the three types of brainstem lesions that affect corticospinal and specific CNs? What are these called? What are the symptoms?
Alternating hemiplegias: corticospinal tract and CN 3 (midbrain lesion), CST and CN 6 (pontine), CST and CN 12 (medulla)
Symp: LMN lesion on 1 side, UMN on alternate side
What is affected by lenticulostriate lacunar capsular stroke?
Internal capsule, caudate, putamen, globus pallidus
What are symptoms of lesion to posterior limb internal capsule?
Contralateral spastic paralysis and loss of conscious somatosensation of body, lower contra face paralysis, contra loss conscious somatosensation face
