Cerebral vasculature Flashcards
What is the blood supply to the brain?
Vertebral artery
Internal carotid artery
Common carotid artery
What is the venous drainage of the brain?
Cerebral veins -> venous sinuses in the dura mater -> internal jugular vein
Which sinus does blood from the great cerebral vein drain into?
Straight sinus
Features of extradural haemorrhage
Trauma
Immediate clinical effects
Features of subdural haemorrhage
Trauma
Delayed clinical effects
Features of subarachnoid haemorrhage
Ruptured aneurysms
Features of intracerebral haemorrhage
Spontaneous hypertensive
Stroke is also known as cardiovascular accident. What is the difference between a CVA and a transient ischaemic attack (TIA)?
TIA resolves within 24hrs, whereas a CVA will be more than 24hrs
What are the risk factors for stroke? (5)
Age Hypertension Cardiac disease Smoking Diabetes Mellitus (CHADS)
Anterior cerebral artery symptoms
Paralysis of contralateral structures
—- leg > arm+face
Disturbance of intellect, executive function and judgement
Loss of appropriate social behaviour
Middle cerebral artery symptoms
"Classic stroke" Contralateral hemiplegia ----- arm > leg Hemianopia Contralateral hemisensory deficits Aphasia if L sided lesion
Posterior cerebral artery symptoms
Homonymous heminopia
Visual agnosia
What are the pyramidal tracts?
Corticobulbar
Corticospinal
Where do the pyramidal tracts travel?
Pass through the pyramids of the medulla
Motor cortex to spinal cord or cranial nerve in brainstem
What do the pyramidal tracts control?
Voluntary movements of the body and face
What are the extrapyramidal tracts?
Rubrospinal
Tectospinal
Reticulospinal
Vestibulospinal
Where do the extrapyramidal tracts travel to?
Brainstem nuclei to spinal cord
What do the extrapyramidal tracts control?
Involuntary movements for balance, posture and locomotion
What innervates the axial musculature?
Anterior corticospinal tract
What innervates limb control?
Lateral corticospinal tract
What is the corticobulbar tract responsible for?
Voluntary movements of the face (and neck)
Function of the vestibulospinal tract
Stabilises head during body movements
Coordinates head movements with eye movements
Mediates postural adjustments
Function of reticulospinal tract
Changes in muscle tone associated with voluntary movement
Postural stability
Function of tectospinal tract
Orientation of head and neck during eye movements
Function of rubrospinal tract
Innervates lower motor neurons of flexors of the upper limb
Negative signs of upper motor neuron lesion
Loss of voluntary motor function
Paresis - graded weakness of movement
Paralysis
Positive signs of upper motor neuron lesion
Increased abnormal motor function due to loss of inhibitory descending inputs Spasticity Hyper-reflexia Clonus Babinski's sign
What is apraxia?
Disorder of skilled movement
Commonly due to lesion of inferior parietal lobe or frontal lobe => motor areas
Common causes include stroke and dementia
Signs of lower motor neuron lesion
Weakness Hypotonia Hyporeflexia Muscle atrophy Fasciculations Fibrillations
What are fasciculations?
damaged motor units produce spontaneous action potentials -> twitch
What are fibrillations?
spontaneous twitching of individual muscle fibres
What is motor neuron disease?
Progressive neurodegenerative disorder of the motor system
What is ALS?
Amyotropic Lateral Sclerosis
What is the function of the basal ganglia?
Decision to move
Elaborating associated movements
Moderating and coordinating movements
Performing movements in order
What is the basal ganglia made up of?
Caudate nucleus Putamen External Globus Pallidus Nucleus accumbens Subthalamic nuclei Substania nigra Ventral pallidum
What is Parkinsons?
Degeneration of dopaminergic neurons that originate in the substantia nigra and project to the striatum
Signs of Parkinsons disease
Bradykinesia Akinesia Hypomimic face Rigidity (cog-wheel) Tremor at rest
What is Huntington’s disease?
Degeneration of GABAergic neurons in the striatum. caudate and then in the putamen
Signs of Huntington’s disease
Choreic movements Speech impairment Difficulty swallowing Unsteady gait Cognitive decline Dementia
What is ballism?
Sudden uncontrolled flinging of limbs and occurs contralaterally
Usually from stoke affecting subthalamic nucleus
What does the vestibulocerebellum do?
Regulates gait, posture and equillibrium
Coordination of head movements with eye movements
A tumour at the vestibulocerebellum can lead to…
Gait ataxia and tendency to fall
What does the spinocerebellum do?
Coordinates speech
Adjusts muscle tone
Coordinates limb movements
Degenerative and atrophy (chronic alcoholism) of the spinocerebellum leads to…
Wide gait and stance
Degenerative and atrophy (chronic alcoholism) of the spinocerebellum leads to…
Wide gait and stance
What does the cerebrocerebellum do?
Coordinates skilled movements Cognitive function Attention Processing language Emotional control
Damage to the cerebrocerebellum leads to…
tremor and affects speech
What is Babinski’s sign?
When the sole of the foot is stimulated with a blunt instrument, the big toe curls upwards
Associated with upper motor neuron lesion
What is clonus?
Involuntary and rhythmic muscle contractions
Loss of descending inhibitions
Associated with upper motor neuron lesion
What is recruitment?
Smaller units are recruited first
As more force is required, more units are required
Allows fine control
What is rate coding?
