Lecture 14 Descending and Spinal Motor Pathways

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534 Neuroanatomy Flashcards on Lecture 14 Descending and Spinal Motor Pathways, created by Mia Li on 17/10/2017.
Mia Li
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Mia Li
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What are the three main descending spinal motor pathways? 1. Voluntary action 2. automatic action 3. reflex action
Lower motor neurons locate in Rexed _____. It is generally asembled into a _____ (proximal muscles) and _____ (distal muscles). IX Medial motor pool (proximal) Lateral motor pool (distal)
The axons exit the SC at ______ at the respective spinal level. ventral root.
Pre-motor interneuron synapses on motor neurons in the ________. Motor pool.
Locate the relative areas of motor pool for muscles of different proximity. See slide 33
What type of nerves are the motor nerves to 1) muscles, 2) muscle spindles? 1) Alpha motor neurons 2) gamma motor neurons
________ motor pool is present throughout the SC while ______ motor pool only exists at plexi. Medial: throughout. Lateral: at plexi only.
Gamma motor neurons innervates the _________ to adjust the length of ________ to maintain alignment with muscle length. Innervates: intra-fusal muscle fibers Muscle spindles.
alpha-gamma co-activation is only activated by _________. UMN drive of LMN.
T/F: Reflex reaction activates gamma neurons. F.
Direct cortical control of movement has pyramid cells in lamina _______ of cerebral cortex going directly to ______ (below the neck) or _______ (facial muscles). Lamina V. SC or brainstem.
Indirect control has additional synapse in the ________. Brainstem.
corticomotor pathways to lower motorneurons are classified based on ________. Number of synapses. (monosynaptic path, disynaptic path, polysynaptic path.)
Interneuron (premotor neurons) in SC are usually found in Rexed ____, ____ or ____. VI, VII, VIII.
T/F: monosynaptic path is a direct pathway. However, disynpatic and polysynaptic paths are indirect pathways. F. They are all direct as long as there is no additional motor neuron in the CNS.
Location of the intermediate UMN in an indirect pathway. Midbrain, pons, medulla.
List the spinal motor tracts and include there starting/ ending points. 1. corticospinal path (lamina V to cervical or lumbar Rexed VII/ IX) 2. Rubrospinal path (red nucleus to cervical rexed VII) 3. Tectosinal path (superior colliculus to cervival Rexed VII) 4. Pontine reticulospinal path (reticular formation in pons to cervival/ lumbar Rexed VII) 5. Medullary reticulospinal path (reticular formation in the medulla to Rexex VII in the cervical /lumbar Rexed VII. 6. Lateral vestibulospinal path (lateral vestibular nucleus to lumbosacral Rexed VII). 7. Medial vestibulospinal path (medial, interior vestibular nucleusn to lumbosacral Rexed VII)
Lateral motor system consists of the _____ tract and the ____ tract. Lateral corticospinal tract (LCST) Rubrospinal tract (RuST)
LCST is in charge of __________ control. Fine motor control.
________ may cover LCST if there is a damage. Rubrospinal tract.
Medial motor system includes the _______, _______, ______ and ______. Ventral (medial) corticospinal tract (VCST) Reticulospinal tracts (ReST) Vestinulospinal tracts (VST) Tectospinal tract (TST)
The ventral (medial) corticospinal tract is in charge of _________. UE/ proximal control
The reticulospinal tracts are in charge of ___________ and _________. Postural control and Anticipatory control
The vestibulospinal tracts are in charge of _________ and __________. Body posture /gravity and Head posture /gravity
The tectospinal tract is in charge of ____________. Control of neck/head/eye movements.
Locate the tracts on a spinal cross section See slide 41
Decussation of LCST locates in the _______. Medulla-spinal cord junction.
Outline the pathway of LCST. See slides 42
M1 correlates to BA___. It contributes to about ___% of all motor neurons. BA4. 50%
% distribution of upper motor neurons in the cortex. Primary sensory cortex (BA1 and BA3): small contribution Premotor cortex and supplementary motor area (BA6): 30% Primary motor cortex(BA4): 50%
Cells in ______ are more in charge of fine motor control while cells in ______ are more concerned with postural adjustment. Supplementary motor area is in charge of ______ and ________. Fine motor control: M1 (BA4) Postural adjustment: BA6. Supplementary motor area: bilateral movements, non-sensory elicited movements
The axons of corticospinal tracts mostly travel in the ______ of the internal capsule. posterior limb
Area associated with hand movement is located in a more _______ location in the motor homunculus as compared to the legs. ventral
Motor aons in the corticospinal tract going to the neck is (nearer/further) to the genu in the internal capsule. nearer.
In the midbrain, the axons of corticospinal tract lie in the __________, with areas corresponding to the legs more _______ and areas corresponding to the UE more _______. Cerebral peduncles. Legs: more dorsal UE: more ventral.
The the axons of corticospinal tract lie in the _____ of the pons. Basis
The cell bodies of the tectospinal tract lie in the ________ of the midbrain; while the cell bodies of the rubrospinal tract lie in the _______. tectospinal tract: superior colliculi rubrospinal tract: red nucleus
Cell bodies of the pontine reticulospinal tract lie in the ___________. Pontine reticular flrmation.
Identify the corticospinal tracts in the pons. See slide 47.
Identify the corticospinal tracts in the rostral medulla and the decussation fibers in the medullary-spinal junction. See slide 48 and 49.
The LCST terminates in Rexed ___ to synapse with spinal interneurons and in Rexed _____ to synapse with lateral motor neurons. Rexed VII: spinal interneurons. Rexed IX lateral motor pool: LMN
Outline the Rubrospinal tract and ventral corticospinal tract. See slide 51.
The medial motor system (ventral corticospinal tract/medial CST/anterior CST) carries more information from _____________. premotor and supplementary motor cortex.
T/F: VCST terminates in the caudal SC. F. Rostral.
T/F: VCST decussates at caudal medulla. F and T... It is called a bilateral path. It sends bilateral axons to each side of the SC.
Pontine ReST is primarily for ______ while medullary ReST is primarily for _________. Pontine: postural control Medullary: automatic movements
Outline the tectospinal tract See slide 55.
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