Nervous System Flashcards
What are the two main sulci seen in the lateral view of the brain?
Central sulcus and lateral fissure
In the brain, is grey matter on the inside or the outside?
Grey matter is on the outside, it is the nerve cell bodies, white matter is the axon tracts and it is on the inside
Where is the primary motor cortex?
Precentral gyrus
How is the primary motor cortex organised?
Somatotopically
Where is the primary sensory cortex?
Postcentral gyrus
How is the primary sensory cortex organised?
Somatotopically
What are of the brain is responsible for reading and writing?
Supramarginal and angular gyri
Which lobe of the brain are the supramarginal and angular gyri found in?
Parietal lobe
Which lobe of the brain is the primary sensory cortex found in?
Parietal lobe
Which lobe of the brain is the primary motor cortex found in?
Frontal lobe
What is the Wernicke’s area responsible for?
Allows for the interpretation of speech
What does a lesion in the Wernicke’s area result in?
Fluent aphasia - the patient can form words and speech but cannot understand speech
What is the Broca’s area responsible for?
Allows for the formation of speech
What does a lesion in the Broca’s area result in?
Non fluent aphasia - the patient can understand speech but cannot form words
What is the arcuate fasciculus?
A bundle of fibres connecting the Wernicke’s area and the Broca’s area
What does a lesion in the arcuate fasciculus result in?
Connectional aphasia - the patient can understand and form speech but is unable to form a coherent response to a question
What is the Exner’s area responsible for?
Planning area for reading and writing
What is the frontal association cortex responsible for?
Intelligence, personality, behaviour, mood, cognitive function
What is the parietal association cortex responsible for?
Spatial skills, 3D recognition (faces, shapes), abstract perception
What is the temporal association cortex responsible for?
Memory, mood, aggression, intelligence
Which hemisphere of the brain is dominant?
Left
What is the right hemisphere of the brain responsible for?
Non verbal language, emotional expression, spatial skills (3D), conceptual understanding, artistic/musical skills
How many pairs of spinal cord nerves are there?
31 pairs 8 cervical 12 thoracic 5 lumbar 5 sacral 1 coccygeal
In the spinal cord is the grey matter on the outside (like the brain)?
No, it is on the inside, the opposite to the brain
What are the three protective structures of the spine?
1 - vertebral column
2 - meninges
a - dura mater (outside)
b - arachnoid mater (middle)
c - pia mater (inside)
3 - space between the meninges filled with cerebrospinal fluid for shock absorptionWhat is discriminitive sensation?
Touch and pressure
What kind of sensation is touch and pressure?
Discriminitive
Is discriminitive sensation (touch/pressure) fast or slow and why?
Fast, 50m/s because the nerves are myelinated
What is non discriminitive sensation?
Pain and temperature
What kind of sensation is pain and temperature?
Non discriminitive
Is non discriminitive sensation (pain/temperature) fast or slow and why?
Slow, 1m/s because the nerves are not myelinated
Which pathway of sensation has a small capsule of connective tissue encasing the nerve endings (corpuscle)?
Discriminitive sensation (touch/pressure) has a small encasement of connective tissue known as a corpuscle surrounding the nerve ending.
Touch - Meissner’s corpuscle
Pressure - Pacinian corpuscle
The corpuscles mean that the stimulus is more precise which is why the sensation is discriminitive
What effect does the free nerve ending have on the non discriminitive pathway?
The free nerve ending means that the stimulus is more diffuse and so the detection of sensation is less exact
What is the name of the pathway that discriminitive sensation uses?
Dorsal column medial lemniscal pathway
Describe the dorsal column medial lemniscal pathway?
Stimulus detected at skin > travels along 1st order neuron through dorsal root (cell bodies form dorsal root ganglion) > gracile fasciculus (lower body) or cuneate fasciculus (upper body) > 2nd order neuron passes through medial lemniscus *crosses over > pons > midbrain > ventral posterior nucleus of thalamus > 3rd order neuron goes through internal capsule > postcentral gyrus
What are the effects of a lesion on the right side of the brain stem along the dorsal column medial lemniscal pathway?
Loss of sensation of discriminitive sensation (touch/pressure) on the left side of the body
What are the effects of a lesion on the left side of the brain stem along the dorsal column medial lemniscal pathway?
Loss of sensation of discriminitive sensation (touch/pressure) on the right side of the body
What are the effects of a lesion on the left side of the spinal cord along the dorsal column medial lemniscal pathway?
Loss of sensation of discriminitive sensation (touch/pressure) on the left side of the body
What are the effects of a lesion on the right side of the spinal cord along the dorsal column medial lemniscal pathway?
Loss of sensation of discriminitive sensation (touch/pressure) on the right side of the body
What is the name of the pathway that non discriminitive sensation uses?
Lateral spinothalamic tract
Describe the lateral spinothalamic tract?
Stimulus detected at skin > 1st order neuron travels through dorsal root > dorsal/posterior grey horn of spinal cord > 2nd order neuron crosses over > travels up spinothalamic tract > joins medial leminscus > pons > midbrain > ventral posterior nucleus of thalamus > 3rd order neuron passes through internal capsule > postcentral gyrus
What are the effects of a lesion on the right side of the brain stem along the lateral spinothalamic tract?
Loss of non discriminitive sensation (pain/temperature) on the left side of the body
What are the effects of a lesion on the left side of the brain stem along the lateral spinothalamic tract?
Loss of non discriminitive sensation (pain/temperature) on the right side of the body
What are the effects of a lesion on the right side of the spinal cord along the lateral spinothalamic tract?
Loss of non discriminitive sensation (pain/temperature) on the right side of the body
What are the effects of a lesion on the left side of the spinal cord along the lateral spinothalamic tract?
Loss of non discriminitive sensation (pain/temperature) on the left side of the body
A lesion in the brainstem is known as what kind of sensory loss?
Associative sensory loss
A lesion in the spinal cord is know as what kind of sensory loss?
Dissocciative sensory loss
What is the corticospinal (pyramidal) tract?
It contains motor neurons which travel from the primary motor cortex to innervate muscle fibres
Describe the pathway of the corticospinal tract?
Primary motor cortex > upper motor neuron travels through internal capsule > midbrain > pyramidal tract > pons > medulla pyramids > 15% ventral corticospinal tract/85% lateral corticospinal tract > ventral grey horn > ventral root > innervates muscle fibres
What causes spastic paralysis?
A lesion that occurs along the upper motor neuron. The lower motor neuron will no longer receive signals from the upper motor neuron (and therefore the brain) so it oly receives other stimuli which causes spastic movements
What causes flaccid paralysis?
A lesion that occurs along the lower motor neuron. The lower motor neuron will not fire at all, and so muscle fibres will not be activated
What is the function of the substantia nigra?
It makes and releases dopamine, a neurotransmitter which allows smooth movement
What is the function of the basal ganglia system?
It is responsible for the initiation of movement, fine motor control and mood expression through body language
What is the function of the cerebellar system?
It is responsible for the termination of movement and ballistic movement
Describe the basal ganglia system pathway of a healthy patient
Substantia nigra releases dopamine into the lower striatum > causes a GABA neuron to fire into the globus pallidus externa > allows firing of of globus pallidus interna neuron > allows firing of neuron into the ventral anterior ventral lateral thalamus > triggers glutamate neuron firing into upper motor neuron in the cerebral cortex
What happens along the basal ganglia system pathway in Parkinson’s patients?
Substantia nigra stops producing dopamine > cells from striatum are unable to fire into globus pallidus externa > increase in GABA neuron firing from globus pallidus to VA-VL > inhibits firing of gllutamate neuron from VA-VL to upper motor neuron > results in Parkinson’s symptoms
What are some treatments for Parkinson’s disease?
L-dopa, lesion on thalamus, lesion on globus pallidus, deep brain stimulation, cell transplantation
Name four key “landmarks” seen in the brain?
Central sulcus, lateral fissure, parieto-occipital sulcus, pre-occipital notch
What is the function of the cerebral aqueduct?
It produces cerebrospinal fluid
