20. Pathology of the Central Nervous System- 1 Flashcards
(31 cards)
Functions of the nervous system
Basic : Sensory → Motor
(mediated by central and peripheral nervous system, autonomic and somatic)
Higher : Consciousness Complex and learned motor skills Memory and planning Communication/language etc…
Brain
Cerebral hemispheres Grey matter White matter Basal ganglia Ventricular system Brain stem Cerebellum
Meninges
Membranous coverings of the central nervous system
Protective function and important in production of cerebrospinal fluid
Blood vessels - Arteries
The cerebral arteries supply a defined territory within the cerebral cortex
If blood supply to a particular part of the brain is interrupted, the patient will develop symptoms due to lack of function of the part of the brain supplied by that vessel
The skull
The skull is a bony box which cannot expand
If the volume of tissue or fluid inside the skull increases the intracranial pressure rises
This results in herniation where a part of the brain moves from one compartment of the skull to another
Herniation
Brain herniation frequently presents withabnormal posturing[2]a characteristic positioning of the limbs indicative of severe brain damage. These patients have a loweredlevel of consciousness, withGlasgow Coma Scoresof three to five.[2]One or both pupils may be dilated and fail to constrict in response to light.[2]Vomiting can also occur due to compression of thevomiting centerin themedulla oblongata.
Spinal Cord
Communication of motor and sensory functions between brain and peripheral nervous system
Basic Neuroanatomy
Spinal and cranial nerves
Branches of above linking CNS to peripheral sensory receptors and effector organs (muscles & glands)
Autonomic and somatic nervous systems
Cells…
Neurons - the processors
Glial cells - supporting functions
- Schwann cells astrocytes & oligodendrocytes
Localisation of motor and sensory territories
Post-central Gyrus = Sensory cortex
Pre-central gyrus = Motor cortex
Speech and language
Broca’s area - Frontal lobe, anterior to pre-motor cortex
- Predominantly responsible for speech
production
Wernicke’s area - Temporal lobe, posterior to auditory
cortex
- Speech processing and comprehension
of written and spoken language
Basic functional anatomy of the CNS
Frontal lobe Parietal lobe Temporal lobe Occipital lobe Brain stem Cerebellum
Frontal lobe
Complex executive functions involved in decision making; Emotional reactions: Formation of some types of memory; Motor cortex; Olfactory function; Generation of fluent speech
Parietal lobe
Sensory cortex and processing of sensory information
Temporal lobe
Language functions including auditory cortex and comprehension of written and spoken words; Memory
Occipital lobe
Visual cortex
Brain stem
Conduction of major motor and sensory pathways; Control of cardiorespiratory function and consciousness; Cranial nerve roots
Cerebellum
Precise motor control; ?Others – language, attention (not yet well defined)
Basic functional anatomy of the CNS
Spinal cord nerve roots:
Specific spinal nerves innervate defined motor functions and sensory territories
Damage to spinal cord at a specific level will cause loss of function of spinal nerves below that level
Sensory
Dermatomes:
General and focal abnormal neurology
Focal neurological signs:
a set of symptoms or signs in which causation can be localized to an anatomic site in the central nervous system
Generalised neurological abnormality:
Essentially an alteration in level of consciousness
Clinical application (1)
People who have regular contact with patients are often more likely to notice subtle changes in neurological parameters allowing prompt investigation and treatment
Basic neurological examination often allows localisation of lesion/injury in a patient with focal neurology
Clinical application (2)
Imaging is usually required to confirm and better characterise the nature of the pathological process
Identification of the likely site by examination can assist in the precise radiological identification of a lesion
Assessment of consciousness allows identification of progression of a neurological insult
Examples of focal neurological signs
Frontal lobe
Anosmia
Inappropriate emotions
Expressive dysphasia
Motor impairment
Examples of focal neurological signs
Parietal lobe
Receptive dysphasia
Sensory impairment
