Control of movement Flashcards
What are the three different kinds of motor neurons?
Somatic
Visceral
Special neurosecretory
What are somatic motor neurons?
Supply voluntary (striated) muscles
What are visceral motor neurons?
Autonomic neurons which supply involuntary (smooth) muscles
Describe upper motor neurons
Above the point where the cerebral cortex and anterior horn synapse
Describe lower motor neurons
Peripheral nerve neurons beyond where the cerebral cortex and anterior horn synapse
What are some signs of defects related to upper motor neurons?
Spastic paralysis
No muscle atrophy
Hyper-reflexivity
Presence of babinski reflex in adults
What are some signs of defects related to lower motor neurons?
Flaccid paralysis
Atrophy of muscles
Hyporeflexivity
Babinski not present
What are three types of reflexes?
Spinal reflexes (e.g. patella tendon reflex) Brain stem reflexes (e.g. vomiting reflex) Cortical reflexes (e.g. pupillary reflex)
What are monosynaptic reflexes?
One synapse only
E.g. stretch reflex
Explain the NS response during the stress reflex.
Tap on the patella tendon detected
Excessive stretch detected
Impulse sent to spinal cord via sensory neuron
Synapse directly with motor neuron
Impulse sent to muscle via motor neuron
Muscle fibres contract - counteracting the original stimulus
What are polysynaptic reflexes?
Two or more synapses involves
E.g. withdrawal (flexion) reflex
Explain the NS response to stepping on a pin
Sensation sent to spinal cord via sensory neuron
Synapses with motor neurons (more than one) [front and back leg muscles]
Allows us to withdraw leg and keep balance
Describe what would occur when there is damage to cranial nerves.
Optic nerve damage
Damage to 3, 4 or 6 - double vision
Shingles in 5 - spots and pain on face
Virus infection in 7 - Bell’s palsy
Streptomycin damage to 8 - loss of hearing and balance
Motor neuron disease in 9, 10, 11 - inability to swallow
What would occur if disease affects the spinal cord
Grey matter damage White matter damage Tertiary syphilis Polio ALS: amytrophic lateral sclerosis
Describe cortical control of movement
Primary motor cortex receives information from other cortical areas.
Sends commands to the brainstem and spinal column
Basal ganglia and cerebellum provide adjustments ot these commands.