Anatomy of the Central Nervous System
The brain can be subdivided into several distinct regions:
The cerebral hemispheres can be further divided into four lobes:
The frontal lobe is concerned with higher intellectual functions, such as abstract thought and reason, speech (Broca's area in the left hemisphere only), olfaction, and emotion. Voluntary movement is controlled in the precentral gyrus (the primary motor area).
The parietal lobe is dedicated to sensory awareness, particularly in the postcentral gyrus (the primary sensory area). It is also concernes with abstract reasoning, language interpretation and formation of a mental egocentric map of the surrounding area.
The occipital lobe is responsible for interpretation and processing of visual stimuli from the optic nerves, and association of these stimuli with other nervous imputs and memories.
The temporal lobe is concerned with emotional development and formation, and also contains the auditory area responsible for processing and discrimination of sound. It is also the area thought to be responsible for the formation and processing of memories.
The cerebral hemispheres are supplied by three main arteries:
(the areas supplied by each artery can be seen by clicking on the names above)
Stenosis or occlusion in any of these arteries will have an effect on the area of brain they supply; the effect will depend on the degree of occlusion, and where in the artery the occlusion is (if it is in one of the terminal branches the effect may be fairly small, but if it is at the base of the artery the effect will be very large).
Occlusion results in ischaemic damage to the cerebral tissues- this is called an 'ischaemic stroke'- and will therefore affect whatever system that particular region controls, often leaving a permanent residual deficit even if the cause of the ischaemia resolves.
The brain can be subdivided into several distinct regions:
- The cerebral hemispheres form the largest part of the brain, occupying the anterior and middle cranial fossae in the skull and extending backwards over the tentorium cerebelli. They are made up of the cerebral cortex, the basal ganglia, tracts of synaptic connections, and the ventricles containing CSF.
- The Diencephalon (not shown above) includes the thalamus, hyopthalamus, epithalamus and subthalamus, and forms the central core of the brain. It is surrounded by the cerebral hemispheres.
- The Midbrain (not shown) is located at the junction of the middle and posterior cranial fossae.
- The Pons sits in the anterior part of the posterior cranial fossa- the fibres within the structure connect one cerebral hemisphere with its opposite cerebellar hemisphere.
- The Medulla Oblongata is continuous with the spinal cord, and is responsible for automatic control of the respiratory and cardiovascular systems.
- The Cerebellum overlies the pons and medulla, extending beneath the tentorium cerebelli and occupying most of the posterior cranial fossa. It is mainly concerned with motor functions that regulate muscle tone, coordination, and posture.
The cerebral hemispheres can be further divided into four lobes:
The cerebral hemispheres are supplied by three main arteries:
(the areas supplied by each artery can be seen by clicking on the names above)
Stenosis or occlusion in any of these arteries will have an effect on the area of brain they supply; the effect will depend on the degree of occlusion, and where in the artery the occlusion is (if it is in one of the terminal branches the effect may be fairly small, but if it is at the base of the artery the effect will be very large).
Occlusion results in ischaemic damage to the cerebral tissues- this is called an 'ischaemic stroke'- and will therefore affect whatever system that particular region controls, often leaving a permanent residual deficit even if the cause of the ischaemia resolves.
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