Neuroanatomy Flashcards
What is a stroke and two main causes?
Stroke = interruption of blood supply to parts of the brain. 2 main causes:
Ischaemic- blood supply is blocked due to a blood clot (85% of all cases)
Haemorrhagic- where a weakened blood vessel supplying the brain bursts
diff locations of strokes and effects?
Anterior cerebral- loss of blood from anterior cerebral arteries will affect primary motor cortex for lower limb and perineum of contralateral side. Can lead to incontinence due to lack of control of pelvic floor muscles
Middle cerebral- blockage of blood supply here will lead to loss of sensation and motor function of body except for lower limb and perineum. Middle supply also supplies broca’s motor speech area and wernickes sensory speech area. Loss of function can affect how someone speaks and the ability to understand speech
Posterior cerebral- posterior arteries supply primary visual cortex. Blockage here can lead to visual field defects. Posterior supplies hippocampus. Blockage here can lead to memory loss
what is a Intracranial haemorrhage- and the 3 diff types?
Intracranial haemorrhage- result from trauma, cerebral lesions, or haematoma which is the enlargement of a vessel that ruptures. Different types:
Extradural haemorrhage- occurs between skull and dura mater proper. If trauma to the side of the head occurs, haemorrhage will occur in middle meningeal artery, putting pressure on local structures and raises intracranial pressure leading to herniation of cerebellum/damage to brainstem
Subdural haemorrhage- build-up of blood in subdural space (between dura and arachnoid mater). Trauma to the head can cause displacement of the skull which Leads to tearing of veins as they enter superior sagittal sinus (dural venous sinus). This causes a slow build-up of intracranial pressure, hence can appear asymptomatic at the beginning.
Subarachnoid haemorrhage- aneurysms leakage or rupture of circle of willis. Can lead to severe headache and loss of consciousness. Diagnosed by withdrawing heavily blood-stained cerebrospinal fluid through lumbar puncture
Bacterial meningitis-
acute inflammation of the arachnoid and pia with thick, creamy exudate (pus) filling the subarachnoid space
Hydrocephalus-
overproduction of CSF or blockage of ventricular system leads to accumulation of CSF. In neonatal skull increase in pressure will force unfused cranial bones to pull apart leading to cranial abnormalities. In a fused adult skull can lead to rise in intracranial pressure. Treated with shunt draining CSF from ventricular system into a body cavity where it can be reabsorbed
Summary of cerebral artery occlusion
Middle cerebral = paralysis and loss of sensation in trunk and upper limb/ loss of production and interpretation of speech
Anterior cerebral = paralysis and loss of sensation to lower limb and perineum
Posterior cerebral = visual field defects and memory loss
Dyskinesias-
excessive dopamine leads to unwanted involuntary movements
Parkinsons disease , symptoms and causes?
Parkinson’s disease- degeneration and death of neurons. Disorder of basal ganglia
Symptoms- bradykinesia, resting tremor, postural impairment/instability, lead-pipe rigidity, constipation, cognitive impairment, and psychiatric symptoms
Causes- degeneration of dopaminergic neurons of SN = low dopamine level = overactivity of indirect pathway = difficult to initiate movement.
Huntingtons disease , symptoms and causes?
Huntington’s disease- basal ganglia disorder. Inherited, progressive neurodegenerative disorder.
Symptoms- hyperkinetic and unwanted abnormal movements, impairment in co-ordination and balance, cognitive and psychiatric symptoms like psychosis and depression
Causes- Degeneration of caudate nucleus of putamen
Increase direct pathway, decrease indirect pathway = inhibition of unwanted movements
Anxiety/PTSD/Bipolar/panic disorder/depression-
amygdala disorder
Alzheimer disease-
severe atrophy of hippocampal formation leading to amnesia for recent events and inability to learn new info of an autobiographical kind i.e. loss of episodic memory
Semantic dementia-
atrophy of middle and inferior temporal neocortical gyri. Patients lose meaning of words and percept’s i.e. their knowledge of the world (semantic memory). Other symptoms include associate agnosia (don’t remember names/recognise people), episodic memory is preserved
Parkingsons vs huntingtons
Parkinsons disease - bradykinesia:
death of dopaminergic neurons of SNpc = low dopamine = decreased direct pathway and increased indirect pathway = slow movement and tremor.
other symptoms - postural impairment, lead-pipe rigidity, constipation, psychiatric and neurological symtpoms
Hungtingtons disease - excessive unwanted movements:
Degeneration of neostriatum = increased direct pathway and decreased indirect pathway = increased unwanted movement
other symptoms - hyperkinesia, dyskinesia, balance impairment, psychosis, depression. also is inherited.
Frontotemporal dementia (FTD)-
atrophy of prefrontal neocortex and amygdala, symptoms include cognitive deficits (planning/organisation/personality change), loss of primary and social emotions
Clinical testing for somatic sensory pathways?
Dorsal column pathway- fine touch, proprioception (i.e., knowing where limbs are without looking), vibration sense
-Tested using tuning fork on toe (last clin skills)
Spinothalamic tract- pain, temp, crude touch, general touch, pressure
- Transmitted via myelinated A-delta fibres and unmyelinated C-fibres
- Pin prick test (last clin skills)
