neuro lec 4 Flashcards
what are the 3 parts of the basal ganglia?
- caudate nucleus
- putamen
- globus palidus
what is the caudate nucleus + putamen called? what about putamen + globus pallidus?
- caudate nucleus + putamen = “striatum”
- putamen + globus pallidus = “lenticular nucleus”
functions of the basal ganglia? (4)
- facilitating desired movements and Inhibiting competing/undesired movements.
- cognitive functions.
- timing of automatic movements.
- contains motor homunculus in motor regions.
if the basal ganglia is a facilitator, which part of the brain is the initiator?
superior motor area
name 3 disorders of the basal ganglia
- parkinson’s disease (difficulty initiating movements).
- huntington’s disease (difficulty inhibiting involuntary movements).
- tourette syndrome (inhibiting undesired movements, tics, verbal, and thoughts)
describe the DIRECT pathway of the basal ganglia-thalamic-cortical system (4)
- the thalamus excites the cortex (more motor activity).
- GPint inhibits the thalamus.
- striatum inhibits the GPint.
- net result: more excitation of the cortex.
describe the INDIRECT pathway of the basal ganglia-thalamic-cortical system (4)
- subthalamic neurons are firing, increasing GPint neurons.
- net result: inhibition on cortex.
- firing of GPext neurons inhibits the subthalamic neurons, making the GPint neurons less active.
- net result: inhibiting the thalamus.
which pathway does parkinson’s disease affect? what about huntington’s disease?
- parkinson’s: direct pathway (net result of inhibition = difficulty initiating movements, slowness…)
- huntington’s: indirect pathway (net result = difficulty inhibiting movements…)
what are the 3 nuclei related to the basal ganglia?
- substantia nigra
- subthalamic nucleus
- nucleus accumbens
where is the substantia nigra located? what does it produce? what does a loss of these cells result in?
- midbrain
- dopamine
- parkinson’s disease
T or F: the nigrostriatal pathway only excites the direct pathway.
false – has the dual effect of exciting the direct pathway while simultaneously inhibiting the indirect pathway.
what brain part is the subthalamic nucleus part of? what does it play a role in?
- diencephalon
- movement regulation
what is deep brain stimulation? who is it used on? what are its benefits?
- pulse generator sends impulses to subthalamic nucleus
- medically intractable parkinson’s patients
- may alleviate side effects of medication + increase medication tolerance
where is the nucleus accumbens? what does it mediate?
- between caudate and putamen
- mediates goal-directed behaviour and plays a role in addiction
what are the 5 subcortical tracts?
- superior longitudinal fasciculus
- arcuate fasciculus (part of SLF?)
- corpus callosum
- internal capsule
- corona radiata
what is the function of the arcuate fasciculus?
- connects broca’s with wernicke’s area
- basically language processing
what is the function of the corpus callosum? what are its 2 main parts? by what age is it developed?
- integrates info between two hemispheres
- forceps major (“splenum” near occipital lobe) and forceps minor (“genu” near frontal lobe)
- complete by age 4 but growth continues until 30
what is the function of the internal capsule? is it afferent or efferent?
- separates caudate from lenticular nucleus and connects cortex with subcortical structures/brain stem/spinal cord
- bidirectional (efferent AND afferent)
what is the corona radiata?
- fibers of internal capsule radiate to various parts of the cerebral cortex and BG
why is the cerebellum called “little brain”?
bc it has its own cortex and subcortical structures
what are the parts of the cerebellum (3)? which part of the brain is the cerebellum part of?
- vermis (worm): separates cerebellar hemispheres
- primary fissure
- horizontal fissure
- metencephalon
what are the 3 cerebellar nuclei? describe the function of each + what happens when there is a lesion.
- fastigial nucleus: vestbiular, motor, gait, and posture. lesions = loss of balance and involuntary movements.
- interpositus nucleus: motor coordinating agonist and antagonist muscles. lesions = tremor.
- dentate nucleus: fine motor control of voluntary movements. lesions = ataxia.
what are the 3 cerebellar peduncles? what kind of input is each related to?
- superior: output from Cb.
- middle: input to Cb via pons (movement + cognition).
- inferior: input to Cb via pons (vestibular).
unlike the cerebral cortex, the cerebellum receives input from, and controls output to, the____ side of the body, and damage to the cerebellum therefore results in deficits to the ____ side of the body.
ipsilateral
ipsilateral
which output zone is each cerebellar nucleus related to?
- fastigial nucleus = medial zone (vestibular spinal cord and thalamus)
- interpositus nucleus = intermediate zone (midbrain and thalamus)
- dentate nucleus = lateral zone (cortex and thalamus)
function of the brainstem? what is it made of? what are its main 3 structures?
- connects spinal cord + cerebrum
- external = white matter, internal = gray matter
- midbrain, pons, medulla
which -cephalon is the midbrain, pons, and medulla related to?
- midbrain = mes
- pons = met
- medulla = mye
what makes up the ventral part of the midbrain? (1)
- cerebral peduncles/crus cerebri (white matter)
what makes up the dorsal part of the midbrain? (2)
- superior colliculi: integrates visual, auditory and somatosensory info for eyes and head
- inferior colliculi: relays auditory stimuli from cochlea to cortex
what is the function of the rostral part of the midbrain?
merges with diencephalon
what are the components of the internal part of the midbrain? (3)
1.substantia nigra
2. cerebral aqueduct
3. periaqueductal gray (involved in involuntary vocalization and pain sensation)
what makes up the dorsal part of the pons? (2)
- 4th ventricle which widens into medulla
- pineal gland (epiphysis) and produces melatonin
what makes up the lateral part of the pons? (1)
large root of trigeminal nerve (CN V)
what makes up the internal part of the pons? (2)
- lateral lemniscus: auditory pathway… connects to inferior colliculus
- medial lemniscus: touch, vibration, proprioception… connects to thalamus and cortex
what makes up the ventral part of the medulla? what is crucial about this part?
- pyramids (white matter)
- crucial: 85-90% or the fibres cross the midline in the decussation of the pyramids
what makes up the internal part of the medulla?
cranial nerve nuclei (9, 10, 11, 12)
what makes up the dorsal part of the medulla?
- fourth ventricle
- fasciculus gracilis (legs)
- fasciculus cuneatus (arms)
- olive (sound)
- central pattern generator (chewing, swallowing, respiration)
T or F: the spinal cord is longer than the vertebral column
false – shorter!
spinal cord ends at the ____ and nerves continue to the ____
- conus medullaris
- cauda equina
in the spinal cord, ___ matter is on the periphery, ___ matter is centrally
- white
- grey
what input does the dorsal vs ventral horn receive?
- dorsal = afferent (sensory)
- ventral = efferent (motor)
what white matter connects dorsally and ventrally?
- dorsally = dorsal columns (afferent)
- ventrally = corticospinal tract (efferent)
motor nerves have their cell body in the ___.
spinal cord
sensory nerves have their cell body in the ____.
spinal ganglion (outside of spinal cord)
damage to upper motor neurons (eg strokes, tumors) can influence the pyramidal tract or extrapyramidal tract. how do symptoms differ?
- pyramidal: impact voluntary movements… increases spasticity, stronger reflexes, hypertonia
- extrapyramidal: reduced reflexes, hypotonia
what does damage to lower neurons do to muscles?
loss of muscle innervation, muscle atrophy
corticospinal/pyramidal tract: where is the upper vs lower neuron located?
- upper: cortex
- lower: spinal cord
corticospinal/pyramidal tract:
fibers that do cross control the ____.
fibers that do not cross control the ____.
- arms/legs
- trunk/head
whats a dermatome vs myotome?
- Dermatome: area inervated by Dorsal root neurons
- Myotome: Muscle innervated by ventral root neurons
what are some health conditions that manifest themselves along dermatomes? (3)
- sciatica
- chickenpox
- shingles
what is referred pain?
when CNS perceives pain coming from one part of the body as pain coming from its associated dermatomes/myotomes
