CNS General Overview and Control of Voluntary Movement 2 Flashcards
What is acetylcholine involved in?
cognitive functions, especially memory
What happens with Alzhemer’s disease?
there is damage in the neurons that release ACH
-degeneration of cholingergic neurons
What neurons release ACH?
cholingeric projections in CNS
What is serotonin associated with?
influences sleep, cognition, sensory perception, motor activity, temperature regulation, nociception, mood, appetite, sexual behavior, and hormone secretion
What type of neurons release serotonin?
serotonergic projections
What part of the brain makes serotonin?
raphe nuclei in midbrain
What is involved with dampening ascending pain signals?
nucleus raphe magnus
What does dopamine do in the brain?
reward, emotion, cognition, memory, and motor activity
What neurons release dopamine?
dopaminergic projections in the CNS
What releases dopamine into the basal nuclei?
substantia nigra
What do dysfunctions of the dopaminergic pathway cause?
addiction, schizophrenia, psychoses, and learning deficits
What pathway degenerates in Parkinson’s?
neurons in the substantia nigra compacta that project into the basal nuclei
Where do neurons in the ventral tegmental area project into?
the nucleus accumbens and the prefrontal cortex
What does norepinephrine do?
impact all areas of the brain and facilitates excitatory synaptic transmission leading to attention and arousal
What part of the brain makes norephinephrine?
locus coeruleus
What do all classes of antidepressants do?
appear to enhances the synaptic availability of serotonin, norephinephrine, or dopamine
What are the two groups of upper motor neurons?
brainstem and corticospinal pathways
What is always released onto muscles?
ACH
-to nicotinic receptors
-cause EPSPs only
What do UMNs from the cerebral cortex do?
initiate and direct sequences of voluntary movement
What do UMNs from the extrapyramidal pathways do?
direct subconscious muscle tone, posture, balance, and orientation of head and body
What do lower motor neurons release?
ACH
What type of neurons are lower motor neurons?
cholinergic
Where does the ACH from lower motor neurons bind to?
nicotinic receptors on skeletal muscle
What does damage of the upper motor neuron do?
cause spastic paralysis on muscles on opposite sides of the body
What is the reflex from damage to upper motor neurons?
Babinski Reflex
What does damage to the lower motor neurons cause?
flaccid paralysis of muscles on the same side of the body
What are the three parts of the motor cortex?
-premotor area/cortex
-supplementary motor area/cortex
-primary motor area/cortex
What does the the premotor cortex do?
set posture at the start of planned movement
-determines the over all movement plan
What does the primary motor cortex do?
activates specific muscles to execute the plan
-more than half of the primary motor cortex is devotes to controlling the muscles of the hands and muscles of speech
What does the supplementary motor cortex do?
involved in organizing or planning. motor sequences
What do lesions in the supplementary motor cortex do?
produce awkwardness in preforming complex activities and difficulty with bimanual coordination
What do axons of neurons from supplemental and primary motor cortex make up?
the cortiospinal and corticobulbar
What is another name for the corticospinal tract?
direct motor pathway
Where do fibers that originate in the motor cortex go?
descend through the internal capsule of the cerebrum
What do the axons of the corticospinal tract do in the medulla oblongata?
form bundles known as pyramids
What happens to 90% of the that form pyramids in the medulla?
they cross over to the contralateral side and form the lateral corticospinal tract of the spinal cord and go to the distal muscles of the body
What happens to the other 10% of the axons that form the pyramids in the medulla?
they do not cross over and form the anterior corticospinal tract and go to the proximal muscles
Where do the lateral and anterior corticospinal nerves synapse?
with the lower motor neurons in the ventral horn of the spinal cord
What is the start and end of the corticobulbar tract?
fibers originate in the motor cortex and terminate on nuclei in the brainstem
What cranial nerves receive input from the corticobulbar tract?
oculomotor, trochlear, trigeminal, abducens, facial, glossopharyngeal, vagus, accessory, and hypoglossal
What does the corticobulbar go?
innervates the lower motor neurons that control conscious control over skeletal muscles the move the eye, jaw, face, and some muscles of the neck and pharynx
What are the descending motor pathways that originate in the brainstem and regulate lower motor neurons?
rubrospinal
tectospinal
vestibulospinal
reticulospinal
Where are the upper motor neurons of the rubrospinal tract?
red nucleus in midbrain
Where does the rubrospinal tract cross over?
midbrain
What is the function of the rubrospinal tract?
upper limb muscle tone and movement
Where are the upper motor neurons of the tectospinal tract ?
midbrain (superior and inferior colliculi )
Where does the tectospinal tract cross over?
midbrain
What is the function of the tectospinal tract?
regulation of eye, head, and neck in UL position in response to visual and auditory stimuli
Where are the upper motor neurons of the vestibulospinal tract?
vestibular nucleus (pons and medulla)
where does the vesitublospinal tract cross over?
it doesnt
What is the function of the vestibulospinal tract?
regulation of balance and muscle tone
Where are the upper motor neurons of the reticulospinal tract?
medial RS (Pons+) lateral RS (medulla-)
Where does the reticulospinal tract cross over?
it doesnot
What is the function of the reticulospinal tract?
regulates muscles of the trunk and limbs for maintaining posture and tone in response to ongoing body movements
What is the basal nuclei involved in?
initiating and terminating movements, suppressing unwanted movements and establishing a normal level of muscle tone
What regulates the activity of upper motor neuron?
the basal nuclei via the thalamus
What are two diseases of the basal nuclei?
parkinsons and huntingtons
What is parkinson’s disease?
-hypokinetic disorder
-loss of dopaminergic neurons from substantia nigra
-slow movements, tremor, shuffled gate
What is huntingtons disease?
-hyperkinetic disorder
-autosomal dominant
-loss of GABAergic neurons
