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Flashcards in Central Nervous System Deck (46)
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Functions of CNS

basic = sensory + motor (mediated by CNS and PNS, autonomic and somatic)
higher = > consciousness, complex and learned motor skills, memory and planning, communication/language


Brain structure

cerebral hemispheres:
- grey matter
- white matter
- basal ganglia
- ventricular system
brain stem



membranous coverings of the CNS
protective function - important in CSF production
> dura mater
> arachnoid mater
> pia mater


Blood vessels in CNS

cerebral arteries -
- if blood supply to a particular part if the brain is interrupted, the patient will develop symptoms due to the lack of function of the part of the brain supplied by the vessel
cerebral veins -
- venous blood drains eventually to the internal jugular vein


The skull

cannot expand
if the volume of tissue/fluid inside the skull increases the intracranial pressure rises = herniation
herniation is where a part of the brain moves from one part of the skull to the other


Spinal chord

8 cervical nerve pairs
12 thoracic nerve pairs
5 lumbar nerve pairs
5 sacral nerve pairs
1 coccygeal nerve pair


Peripheral NS

spinal and cranial nerves
branches off linking CNS to peripheral sensory receptors and effector organs (muscles and glands)
autonomic and somatic


Name the cells in PNS and CNS

1. neurones - the processors
2. glial cells - supporting functions
> Schwann cells
> astrocytes
> oligodendrocytes


What area of the brain is the motor cortex?

pre-central gyrus


What area of the brain is the sensory cortex?

post-central gyrus


What and where is Broca's area in the brain?

frontal lobe, anterior to the pre-motor cortex
predominantly responsible for speech production


What and where is Wernicke's area in the brain?

temporal lobe, posterior to auditory cortex
responsible for processing speech and comprehension of written and spoken language


Frontal lobe

decision making, emotional reactions, formation of some types of memory, motor cortex, olfactory function, fluent speech


Parietal lobe

sensory cortex, processing of sensory info


Temporal lobe

language functions and auditory cortex, comprehension of written and spoken words, memory


Occipital lobe

visual cortex


Brain stem

conduction of major motor and sensory pathways, cardio-respiratory functions and consciousness, cranial nerve roots



precise motor control, language attention ??


Spinal chord nerve roots

specific spinal nerves innervate defined motor functions and sensory territories
damage to spinal chord at specific level = loss of function of spinal nerves below that level


What are focal neurological signs?

a set of symptoms or signs in which causation can be localized to an anatomic site in the central nervous system


What is generalised neurological abnormality?

Essentially an alteration in level of consciousness


Frontal lobe focal neurological signs
Parietal lobe focal neurological signs
Temporal lobe focal neurological signs

anosmia (loss of smell), inappropriate emotions, expressive dysphasia, motor impairment

receptive dysphagia, sensory impairment

cortical deafness, receptive dysphagia


Spinal chord lesions

Physical examination helps to identify the level of injury in spinal cord lesions
Signs limited to a single dermatome or nerve root suggest either a focal nerve root injury or injury to a peripheral nerve
Signs affecting several nerve roots below a certain level eg. Complete paralysis of body and legs with maintained head and neck movement is caused by injuries to the cervical spine (usually traumatic)


Diffuse neurological injury

Usually manifest as impairment of consciousness
Most often due to increased intracranial pressure
May occur as a primary process or as a secondary to response to a focal injury


How do we assess consciousness?

A: alert
V: voice
P: pain
U: unresponsive


Cerebrovascular diseases

strokes, TIA, intracerebral haemorrhages
2 main pathological processes:
> hypoxia, ischaemia, infarction due to impaired o2/blood supply
> haemorrhage from CNS vessels
if blood flow is decreased to a portion of the brain, survival of tissue depends on:
- collateral circulation
- duration of ischaemia
- magnitude and rapidity of decrease blood flow
reduced blood flow to the whole brain = global hypofusion = generalised neuronal dysfunction



Face (drooping)
Arms (may not be able to raise them)
Speech (slurred)
loss of function lasting greater than 24 hours
2 types;
- ischaemic
- haemorrhagic
risk factors: hypertension, DM, heart disease, hyperlipidaemia


Causes of a stroke

hypoxia of the brain due to blockage of blood vessels by an atheroma or embolus
bleed into the brain caused by hypertension or aneurysm
Left MCA territory infarct -
- damage to speech area in L hemisphere = loss of speech (aphasia)
- damage to L visual pathway = loss of vision to R (hemianopia)
- damage to left motor cortex and internal capsule = weakness of R face, arm and leg


Management of strokes

Aspirin, Clopidogrel
occupational therapy


Transient ischaemic attack (TIA)

temporary loss of function that resolves itself within 24 hours
"mini strokes"
symptoms similar to stroke but rapid recovery
treatment = anti-platelet therapy eg. Aspirin, Clopidogrel, control BP, lower cholesterol