Terms in this set (60)
Motor infor descends through the
motor infor is conveyed through the ____
Motor info is conveyed through the ventral root and _____ to the lower neurons
LMNs transmit signals to _____ to contract
What are the primary components of a motor unit?
-a single alpha neuron
-the muscle fiber it innervates
Why is Ach released in minute amounts?
to prevent muscle atrophy
What is the release of Ach referred to? (to prevent muscle atrophy)
mini end plate potentials
When a muscle is excited, Ach is released by a _____ at the neuromuscular junction
After the Ach is released at the neuromuscular junction, it binds to a receptor known as_____ (on the muscle)
When the Ach binds to the sarcolemma, this causes____
Depolarization (on the sarcolemma) causes/ allows the action potential to be propagated to cause a____
What do alpha and gamma motor neurons have in common?
-cell bodies in the ventral horn
-exit through to a peripheral nerve and innervate that muscle
alpha motor neurons are____ in size.
Alpha motor neurons innervate
Alpha motor neurons function to initiate
Gamma motor neurons are ___ in size.
Gamma axons go to____ fibers in the muscle
monosynaptic phasic stretch reflex
when a muscle is tapped (the brain is not involved, reflexive, not voluntary)
The monosynaptic phasic stretch reflex will not exist when there is damage to the___
The monosynaptic phasic stretch reflex will hyperactivate when there is damage to the ______
UMN (corticospinal tract)
How can movement occur when it is not voluntarily directed from the cortex?
-vestibular connects (posture, activation of eye muscles)
agonist contracts while antagonist is inhibited
stability (2 opposing muscles contracting at once)
Inhibit flexors when a pt. has ___
tract that makes head turn via superior colliculus when there is a noise
Balance in response to head turn (tract)
Neck and upper back response to head movement (tract)
Flexion-extension patters (tract)
Where would a CST lesion have to be to be ipsilateral and affect the moto system
below the pyramidal decussation
2 descending influences on our movement
cerebellum and basal ganglia
What areas of the cortex contribute to planning and exection of our movements?
premotor area and supplementary motor area
UMN lesions occur in the ____
LMN lesions occur after exiting the
spinal cord (in the peripheral nerves)
UMN lesions result in distrubance of the ____
UMN lesions result in disturbance of the CST so you get____
paresis, loss of inhibitory influence on interneurons, spasticity
The muscle spindle is composed of
Intrafusal fibers are specialized to be a
sensory organ in the muscle that respond to stretch
The intrafusal fibers detect___
the length and velocity of change in the muscle
Elongation happens when extrafusal fibers are
Sensory info from the muscle spindle may be sent to___
-the spinal cord (reflexively and to make corrections to small errors )
- brainstem (corrections to movement
-cerebellum and cortex (to provide proprioceptive info)
What is the primary focus of the golgi tendon organ
converts tension in the muscle tendons to neural activity
Where is the golgi tendon organ conveyed?
through the spinal cord and back out to LMNs
What are dermatomes?
they show the distribution of how sensory info is conveyed on the skin according to the level of spinal cord innervation of a single spinal nerve
What is a myotome?
a group of muscles innervated by a segmental spinal nerve
What is a segmental lesion?
interferes with function only at the level of the lesion
What is a ventral tract lesion?
problems in the tract with loss of function below the lesion (ALS, DCML, CST)
Central Cord syndromecrosses
crosses through the anterior white commissure, loss of segmental and ipsilateral ALS infor, large lesion affect CST and affect upper limb function
Anterio Cord Syndrome
lesion to the anterior cord which interrupts ascending ALS pathway and descending motor pathways
pain and temp
Anterior cord syndrome results in loss of ___
contralateral pain and temp and ipsilateral motor loss
Brown Sequard Syndrome
hemisection of the spinal cord
ipsilateral loss of DCML and CST and contralateral loss of ALS
Spinal shock following a spinal cord injury
immediately after a spinal cord injury, cord function, below the injury level are depressed/ lost, deep tendon/ stretch reflexes, autonomic function
lack of sensory and motor function in the lowest sacral segment
Incomplete SC injury
preserved sensory or motor function in the lowest sacral segment
Spinal cord neurologic level
the most caudal level with normal sensory and motor function bilaterally
Spinal region reflexes require____
-connections between primary afferents and LNNs
-Effectors (muscles of glands)
Medial Activation system's four tracts from brain stem:
-medial vestibulospinal and lateral vestibulospinal
Is the Medial activation system unconscious or consious?
Signs of UMN lesions
Abnormal cutaneous reflexes, abnormal timing of muscle activation, paresis, hyperstiffness, clasp knife response/ clonus