Central Nervous System (Part 1 - Motor System Focused) Flashcards
state what it is meant by the key term - nervous system
the nervous system comprises all of the nervous tissue in the body
state what it is meant by the key term - CNS
the CNS is the ‘control centre’ for human movement; integrating information for coherent action
all CNS elements contain what 2 things ?
- grey matter - neural cell bodies, dendrites, unmyelinated axons
- white matter - myelinated axons
what does the CNS do with afferent information
basic afferent information is processed into meaningful perceptions within the CNS
what does the CNS have control over
the CNS has control over the body systems that govern our movement
what does the forebrain consist of ?
the forebrain consists of elements you would most readily associate with cognition, our ability to think, plan, feel and act
state 2 facts about general brain structure
- makes up approx. 2% of total body weight (130-150g)
2. consists of approx. 86 billion neurones
what percentage of the brain consists of the cerebrum ?
85%
what are the two major cell types within the CNS
- pyramidal cells - major output cells
2. non-pyritical cells - major input cells
state 3 facts about the Cerebrum
- the largest and most prominent brain structure
- includes the cerebral cortex, basal ganglia and other structures
- consists of 2 hemispheres and is connected by the corpus collosum (bundle of fibres)
state what it is meant by the key term - cerebral cortex
the cerebral cortex is a folded sheet (2-4 mm) of grey matter; the outer layer covering the cerebral hemispheres
what does the cerebral cortex consist of ?
gyri (crest of folded tissue) and sulci (grooves that divide gyri)
each hemisphere is divided into 4 lobes, what are the names of these lobes ?
- frontal
- temporal
- parietal
- occipital
state a general fact about the 4 lobes
Each lobe receives input from different sensory systems involved in different processes. However, there is significant cross talk between lobes
state what it is meant by the key term - motor cortex
the motor cortex is the area in the frontal lobe, anterior to the central sulcus, fundamental for voluntary motor control and deciding/planning actions
state what it is meant by the key term - Broca’s area
a region of the prefrontal cortex concerned with the production of speech
what does damage to the Broca’s area do ? (2 points)
- Damage in this area causes Broca’s aphasia
2. characterised by hesitant and fragmented speech with little grammatical structure
state what it is meant by the key term - frontal eye field (FEF)
the frontal eye field (FEF) is the area in dorsolateral prefrontal cortex that signals the location of targets and controls the execution of goal-directed movements of the eyes
state what it is meant by the key term - primary motor area
sends motor commands to motor neurones; initiation and co-ordination of voluntary movements
state what it is meant by the key term - pre-motor area
concerned with the organisation of movements before they are initiated
state what it is meant by the key term - supplementary motor area
concerned with the preparation and control of sequential movements
what does the primary motor area contain ?
the primary motor area has large pyramidal neurones
what proportion of the motor cortex is related to hand movement ?
1/3 of the motor cortex is concerned with hand movement
state 2 additional facts about the motor cortex as a whole
- has both dorsal and ventral promotor areas
2. has somatotopic organisation
state what it is meant by the key term - basal ganglia
basal ganglia are a set of subcortical nuclei that are strictly interconnected with the cortex and the brainstem
what are the 5 types of basal ganglia (stop going stupidly slowly nan)
- striatum (caudate and putamen)
- globus pallidus
- substantia nigra
- subthalmic nucleus
- nucleus accumbens
the basal ganglia play an important role in what 4 things ?
- control of voluntary movements
- motor learning
- cognition
- emotion
state, and explain, what the two pathways in the basal ganglia are
- direct pathway - involved in the excitation of a desired motor programme
- indirect pathway - involved in the inhibition of competing motor programmes
explain what the basal ganglia and motor cortex form
form a process loop, whereby basal ganglia enable the desired MP represented in the motor cortex to be excited via the direct pathway and inhibits competing MP’s via the indirect pathway
the appropriate motor programme is selected via the basal ganglia and motor cortex based on the integration of what 3 parameters ?
- motor planning
- sensory information
- predicted consequences of action based on previous experiences
state what it is meant by the key term - Parkinson’s disease
Parkinson’s disease is the degeneration of neurones in the substantia nigra
explain how Parkinson’s disease works (3 points)
- loss of dopaminergic neurones in the substantia nigra
- imbalance in pathways occur, and it deteriorates the ability to choose the correct motor programme
- loss of dopaminergic pathway tips balance towards indirect pathway, reducing the excitatory activity in the motor cortex, reducing voluntary movements
state the 4 symptoms of Parkinson’s disease
- increased likelihood of falling, suffering gait, tremor at rest
- bradykinesia (slowness of voluntary movements)
- akinesia (difficulty in initiating movements)
- hypometria (inadequate amplitude of movements)
state what it is meant by the key term - bradykinesia
slowness of voluntary movements
state what it is meant by the key term - akinesia
difficulty in initiating movements
state what it is meant by the key term - hypometria
inadequate amplitude of movements
state what it is meant by the key term - Huntington’s disease
Huntington’s disease is the selective loss of stratal neurones
explain how Huntington’s disease works
balance is tipped in favour of the direct pathway, without normal inhibitory response of the thalamus, random firing causes inappropriate execution of motor programmes
state and explain the major symptom of Huntington’s disease (2 points)
- cuneiform movements/dyskinesia - continuous movement of the body, especially of the extremities and the face
- resemble adaptive movements, but occur involuntarily and incoherently
state what it is meant by the key term - cerebellum
the cerebellum is the prominent structure situated at the back of the pons (brainstem) and is concerned with motor co-ordination, posture and balance
what does the cerebellum play a key role in ?
the execution of smooth and accurate movements
what is the cerebellum also known as ?
the ‘little brain’
state 2 structural facts about the cerebellum
- accounts for approx. 10% of brain volume
2. accounts for > 50% of the brains neurones
state 4 cerebellum functions
- maintenance of balance and posture
- coordination of voluntary moments
- motor learning
- cognitive functions
what does the cerebellum really do ?
modifies motor programmes of the descending pathway to make movements more adaptive and accurate
what is damage to the Broca’s area called ?
Broca’s aphasia
