Motor I, II, and III Flashcards
Motoneurons innervating axial and proximal muscles are located (laterally/medially) in the ventral horn of the spinal cord.
Medially
Motoneurons innervating distal muscles are located (laterally/medially) in the ventral horn of the spinal cord.
Laterally
Motoneurons innervating extensor muscles are located (ventral/dorsal) to those innervating flexor muscles.
Ventral
(T/F) Interneuron pools in the intermediate gray that innervate motoneurons are segregated in the same way as motoneurons in the ventral horn.
True.
(T/F) Descending tracts are located in the white matter adjacent to the relevant motoneuron pools they control.
True.
Proprioceptive input to a cortical column arises in the joint (proximal/distal) to the muscle that the column controls.
Distal
Cutaneous input to a cortical column arises where?
From a skin region in the path of limb movement that the column controls.
Inputs to the cortical columns travel through the ______________ and _____________ thalamic nuclei.
Ventroanterior and ventrolateral thalamic nuclei
The standard visuo-motor reflex takes about ___ms.
240ms
The standard cortical reflex takes about ___ms.
120ms
90% of the corticospinal tract arises in the ____________ and ___________ cortices.
Precentral and postcentral
Pathways controlling axial and proximal muscles for use in posture typically undergo (phasic/tonic) innervation.
Tonic
(TPP) = Tonic, Proximal, Posture
Pathways controlling distal muscles for use in discrete movements typically undergo (phasic/tonic) innervation.
Phasic
(PDD) = Phasic, Distal, Discrete
Muscle tracts that make use of tonic innervation include:
- Pontine reticulospinal
- Vestibulospinal
- Tectospinal
Tonic = Control Postuer (Axial and proximal muscle groups)
Muscle tracts that makes use of phasic innervation include:
- Corticospinal
- Rubrospinal
- Medullary reticulospinal
Phasic = Control Discrete Muscle Movement (Distal muscle groups)
The lateral corticospinal tract primarily terminates upon (flexor/extensor) interneurons.
Flexor interneurons
The rubrospinal tract usually (activates/inhibits) flexors and (activates/inhibits) extensors of the upper body.
- Activates flexors
- Inhibits extensors
Massive effect on force (flexor part of emergency control; i.e. grabbing onto tree when you fall)
Acts on alpha motor neurons
The medullary reticulospinal tract usually (activates/inhibits) flexors and extensors.
Inhibits flexors
Inhibits extensors
(T/F) Upon entering sleep, the medullary reticulospinal tract hyperpolarizes the body’s flexor and extensor interneurons. This is a defense mechanism to cause paralysis during sleep and prevent movement during vivid or imaginative dreams.
True.
The vestibulospinal tract primarily activates (flexor/extensor) alpha motor neurons and interneurons. It is important in maintaining balance and prevention of injury while falling.
Extensors
The pontine reticulospinal tract typically (activates/inhibits) extensor interneurons.
Activates extensors
Helps you stand up
The tectospinal tract activates (extensor/flexor) interneurons of the upper cervical areas to track objects on the edges of the field of vision by moving the neck.
Extensor
What path do fibers in the corticospinal tract travel after leaving the motor cortices?
- Corona radiata
- Internal capsule (posterior limb)
- Cerebral peduncle (middle third)
- Pons
- Pyramids
- Decussation into lateral and anterior corticospinal tracts
Glutamate is (excitatory/inhibitory).
Excitatory
Inputs to the striatum (caudate nucleus and putamen) from the cerebral cortices use the neurotransmitter _____________.
Glutamate
Inputs to the striatum (caudate nucleus and putamen) from the thalamus use the neurotransmitter ______________.
Glutamate
Inputs to the striatum (caudate nucleus and putamen) from the substantia nigra use the neurotransmitter ______________.
Dopamine
Inputs to the striatum (caudate nucleus and putamen) from the raphe nucleus use the neurotransmitter _______________.
Serotonin
Outputs from the striatum travel to the _________ and _________.
Globus pallidus and substantia nigra
The ___________ and __________ function to regulate output from the striatum.
Subthalamic nucleus and external pallidum (of globus pallidus)
Outputs travel from the striatum to the globus pallidus and substantia nigra. Outputs leaving the internal pallidum and substantia nigra then ascend to the ______________ and descend to the ____________ simultaneously.
- *Ascend** to the thalamus (VA & VL)
- *Descend** to the midbrain (Subthalamic Nuclei)
What are the key functions of the basal ganglia?
- Preparation and planning of movement
- Organization of sequence of movements
- Learning of hierarchically organized movements
- Sensory and motor modulation
What are the key functions of the cerebellum?
- Unconscious control of movement
- Regulation of rapid (preprogrammed) movements
- Posture, muscle tone, and equilibrium
The archicerebellum (flocculonodular) lobe of the cerebellum is primarily involved in (distance judgments/vestibular balance and eye movements/muscle tone control).
Vestibular balance and eye movements
The paleocerebellum (anterior) lobe of the cerebellum is primarily involved in (distance judgments/vestibular balance/muscle tone control).
Muscle tone control
The neocerebellum (posterior) lobe of the cerebellum is primarily involved in (distance judgments/vestibular balance/muscle tone control).
Distance judgments
The cerebellar cortex has a _____________ outer layer, _____________ intermediate layer, and ____________ inner layer.
- Outer molecular layer
- Intermediate Purkinje layer
- Inner granular layer
Mossy fibers terminate on glomeruli containing _____________ dendrites and _____________ axons.
- Granule cell dendrites
- Golgi cell axons
After receiving excitatory inputs from mossy fibers, granule cells climb to the molecular layer and bifurcate, forming ______________ that run perpendicular to the dendrites of Purkinje cells.
Parallel fibers
Parallel fibers provide excitatory input to ______________, which then travel through the cerebellar white matter and form inhibitory synapses on the cerebellar deep nuclei.
Purkinje cells
Parallel fibers provide excitatory input to what other two types of cells besides Purkinje cells?
- Golgi cells (inhibitory output to mossy fibers cells)
- Basket cells (inhibitory output to Purkinje cell one row on either side of the row that was activated by parallel fibers)
(Basket/Stellate) cells provide inhibition by terminating on Purkinje cell dendrites in the molecular layer.
Stellate
(Basket/Stellate) cells provide inhibition by surrounding the Purkinje cell body.
Basket cells
_____________ fibers provide excitatory input to Purkinje cells by wrapping around its cell body and proximal dendrites.
Climbing fibers
- From inferior olive
An easy way to remember excitatory and inhibitory inputs is that excitatory inputs travel (up/down) and inhibitory inputs travel (up/down).
- Excitatory travels up (Mossy fibers, granule cells that become parallel fibers, climbing fibers)
- Inhibitory travels down (Stellate cells, basket cells, golgi cells, Purkinje cells)
___________ cells provide inhibition by terminating on granule cell dendrites within the glomerulus.
Golgi cells
(T/F) Climbing fibers originate in the superior olivary nucleus.
False. Climbing fibers arise exclusively from neurons in the contralateral INFERIOR olivary nucleus.
Afferent information about limb movements is conveyed to the cerebellum by the dorsal spinocerebellar tract for the (upper/lower) extremities.
Lower
Afferent information about limb movements is conveyed to the cerebellum by the cuneocerebellar tract for the (upper/lower) extremities.
Upper
Information about activity of spinal cord interneurons and intended pattern generator outputs is conveyed to the cerebellum by the ventral spinocerebellar tract for the (upper/lower) extremity interneurons.
Lower
Information about activity of spinal cord interneurons and intended pattern generator outputs is conveyed to the cerebellum by the rostral spinocerebellar tract for the (upper/lower) extremity interneurons.
Upper
Mossy fibers traveling through the dorsal spinocerebellar and cuneocerebellar tract enter the (ipsilateral/contralateral) cerebellum through the (inferior/middle/superior) cerebellar peduncle.
- Ipsilateral cerebellum
- Inferior cerebellar peduncle
(T/F) Olivocerebellar fibers decussate before entering the cerebellum as climbing fibers.
True.
Fibers from the most lateral portion of the cerebellum enter the ______________ deep cerebellar nucleus.
Dentate
Fibers from the intermediate portion of the cerebellum enter the ____________ and ____________ deep cerebellar nuclei.
Emboliform and globose
Fibers from the flocculonodular lobe and vermis, the most medial portions of the cerebellum, enter the ______________ deep cerebellar nucleus.
Fastigial
Most outputs of the cerebellum travel through the (superior/middle/inferior) cerebellar peduncle.
Superior
What cerebellar inputs travel through the middle cerebellar peduncle?
- Pontocerebellar
What cerebellar inputs travel through the inferior cerebellar peduncle?
- Dorsal (posterior) spinocerebellar
- Cuneocerebellar
- Olivocerebellar
- Vestibulocerebellar
- Reticulocerebellar
What cerebellar inputs travel through the superior cerebellar peduncle?
- Ventral (anterior) spinocerebellar
What is the mnemonic to remember the deep cerebellar nuclei in order from most lateral to most medial?
Don’t (Dentate) - Most lateral
Eat (Emboliform)
Greasy (Globose)
Food (Fastigial) - Most medial
All movements of the body have an underlying rhythm of __Hz.
10Hz
(T/F) A long latency reflex that stabilizes the body’s posture will become weaker when elicited repetitively.
False. A long latency reflex that stabilizes the body’s posture will become STRONGER when elicited repetitively.
What lesion will cause an intention tremor?
Lateral hemisphere of cerebellum
- Dentate nucleus is located here
- Dysmetria
