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In general where do UMN deliver information to?
descending tracts (w/ UMN axons) from cortical and brainstem centers (supraspinal centers) carry movement information from the brain to LMN (alpha and gamma) and to interneurons
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Where are the three places UMNs terminate on and where?
- Alpha (LMN)
- Gamma (LMN)
- interneurons
- all terminate in the ventral cell column (medial, lateral, throughout)
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How is the ventral cell column organized?
- SOMATOTOPICALLY
- distal muscles=later
- proximal muscles=medial
- extensor muscles=anterior
- flexor muscles=posterior
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What are key factors of the medial activating system in general (function, location, etc.)?
- posture and gross movement of the trunk
- primarily in white matter of anterior funiculus
- proximal musculature & extensors
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What are key factors of the lateral activating system in general (function, location, etc.)?
- fine motor movement, fractionation
- descends in lateral funiculus of SC
- distal musculater and flexors
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Which tracts of the Medial Activating system are bilateral?
- Medial Vestibulospinal tract
- Medial (anterior) Corticospinal tract
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What tracts of the Medial activating system are ipsilateral?
- Pontine (medial) reticulospinal tract
- Lateral vestibulospinal tract
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What is the origin, termination, function, & cortical input of the tectospinal tract?
- Origin: tectum
- Termination: cervical medial motor column cells
- Function: orients head toward auditory, visual or somatosensory nuclei
- Cortical Input: rapid fire so doesn't travel all the way to cortex, but it does have some input
- CONTRALATERAL
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What is the origin, termination, and function of the Pontine (medial) reticuospinal tract?
- Origin: reticular formation of pons
- Termination: medial motor column cells
- Function: facilitates axial and proximal muscle extensors
- Cortical Input: input keeps you standing straight up, not falling
- IPSILATERAL
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What is the origin, termination, function, & cortical input of the Medial Vestibulospinal Tract?
- Origin: medial vestibular nucleus of pons
- Termination: medial motor column cells
- Function: facilitates trunk and neck extensors, senses off balance from the ear
- Cortical input: very litte
- BILATERAL
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What is the origin, termination, function, & cortical input of the Lateral Vestibulospinal Tract?
- Origin: lateral vestibular nucleus of the pons
- Termination: medial motor column cells
- Function: facilitates extensors, inhibits flexors, postural musculature to keep you upright
- Cortical input: ---
- IPSILATERAL
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What is the origin, termination, function, & cortical input of the medial (anterior) Corticospinal Tract?
- Origin: trunk area of precentral gyrus
- Termination: medial motor column cells
- Function: facilitates extensors of axial and prximal musculature, prepares postural system for movement (trunk stability for distal mobility)
- Cortical input: ---
- BILATERAL
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What is the origin, termination, and function of the Lateral Corticospinal Tract?
- Origin: premotor (30%), primary motor (40%), and somatosensory (30%)
- Termination: cells controlling limb flexors
- Function: fractionation, discrete muscle activity
- CONTRALATERAL
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What is the origin, termination, and function of the Rubrospinal Tract?
- Origin: red nucleus of midbrain
- Termination: lateral motor column cells
- Function: facilitates upper limb flexor movements
- CONTRALATERAL
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What is the origin, termination, and function of the Medullary Lateral Rectospinal Tract?
- Origin: medullary recticular formation
- Termination: lateral motor column cells
- Function: inhibits spinal mortor neurons and has a role in modification of motor neural pool
- BILATERAL
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What are the five medial activating systems?
- tectospinal tract
- pontine (medial) rectospinal tract
- medial vestibulospinal tract
- lateral vestibulospinal tract
- medial (anterior) corticospinal tract
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What the three lateral activating systems?
- lateral corticospinal tract
- rubrospinal tract
- medullary (lateral) rectospinal tract
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What are the two non-specific systems?
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What is the origin and function of the cerulospinal tract?
- Origin: locus ceruleus in the brainstem
- Function: enhances activity of interneurons and motor neurons of SC
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What is the origin and function of the Raphespinal tract?
- Origin: raphe nucleus in the brainstem
- Function: enhances activity of interneurons and motor neurons of SC
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What tract does the corticobulbar tract travel with?
lateral corticospinal tract
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Where does the corticobulbar tract terminate?
- nuclei of cranial nerves
- III, IV, V, VI, VII, XI, XII, IX, X
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Projections of the corticobulbar tracts are primarily IPSI, CONTRA, or BI- lateral?
BILATERAL
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What are the exceptions to the projections of the corticobulbar tract?
- IV: ipsilateral
- VII: upper face bilateral, lower face contralateral
- XI: contralateral
- XII: contralateral
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What is interesting about the trochlear nerve?
IV: it is the only peripheral nerve to cross the midline
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What does the facial nerve control?
VII: sagging of the face
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What does the Hypoglassal nerve control?
XII: sticking out the tongue
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What does the Spinal Accesory Nerve Control?
XI: SCM and trap
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