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Gray's anatomy online
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The Human brain is the most complex structure in the known universe. It is in control of a plethora of bodily functions; processing sensory information; regulating biochemical processes; coordinating movement and of course, providing us the ability of higher thought/perception. There are three primary areas of the human brain:
• The rhombencephalon
• The mesencephalon
• The forebrain
The rhomencephalon is composed of the brain stem and cerebellum and controls a variety of processes. It is located in the cranial cavity.
One fundamental structure that composes the hindbrain is the medulla. The medulla oblongata is directly above the spine and is so indispensable to life that pathogens disturbing it are quite often fatal.
An additional major part of the brain is the cerebellum. This part is sometimes called the “little brain”. It looks different to the rest of the brain. It has a surface of densely folded gray matter. It is mainly concerned with movement.
The Pons measures in the region of 2cm in size and is located between the midbrain and the lower part of the brain stem (medulla). It is made up of nuclei that deal with sleep, respiration, swallowing, bladder control, hearing, equilibrium, taste, eye movement, facial expressions, facial sensation, and posture.
The midbrain is above the Pons and inferior to the cerebral hemispheres. The rear part of the mesencephalon is known as the tectum, it is significantly involved in reflexes relating to auditory processes and sight (e.g. the eye movement, pupil size, lens shape). The anterior section of the mesencephalon is referred to as the tegmentum, it is in essence an elaborate network of neurones in charge of unconscious homeostatic and reflexive pathways.
The prosencephalon is above both
and the mesencephalon as well as being the most ventral. It has key roles in the following actions:
Directs sensory impulses through the body
The Forebrain is split into 2 fundamental structures:
The neocortex is the folded outer portion of the brain, in humans it is between just less than half a cm deep. It has the highest levels of non- insulated grey matter of any region of the brain. The cortex forms folded bulges (thus significantly increasing the region without expanding the volume) called gyri; so much so that more than 75% of the brain lie in these folds (known as sucli).
The Frontal lobe is the most forward part of the lobes and is additionally superior to the temporal lobe. This section of the brain is linked with some of of the the most crucial traits associated with personality (e.g ability to understand future results of events), learning, impulse control, and priority of actions. It is host to most of the brain’s dopamine receptors (these are the crucial way through which learning is developed).
The temporal lobes are behind the frontal and parietal lobe and behind the occipital lobe. Research suggest they are the critical part of the brain involved in declarative memory; damage to the temporal lobes can result in an incapability to form memory after the event (anterograde amnesia). They contain the hippocampus (long-term memory) and are involved in auditory and higher sight perception (e.g. facial recognition).
The parietal lobe is ahead of the occipital lobe, behind the frontal lobe and above of the temporal lobes. The border between the frontal lobe and the parietal lobe is marked by the central sulcus. The border between the occipital lobe and the parietal lobe is marked by the parieto-occipito sulcus and the border between the temporal lobe and the parietal lobe is marked by the lateral sulcus. The parietal lobe coordinates information from multiple senses in order to establish spatial orientation.
The Occipital lobe is the most posterior of all the main lobes of the brain. Anatomically this portion contains most of the visual cortex (Brodmann area 17) and damage to the occipital lobes results in significant homonomous vision loss (i.e. the effect is the same in both eyes). The occipital lobes are where shape, colour, and like the temporal lobes, facial recognition take place. Projections from the occipital lobe to the superior temporal-parietal section are essential for perceiving motion of objects.
The basal ganglia are a area of the corpus striatum and are in essence a set of interconnected nuclei within the brain. Messages from the cerebrum passes to the basal ganglia where it is processed and then sent back through the thalamus. There are a great deal of connections and pathways within and although the basal ganglia have long been known to be involved in movement; it is known this is not there sole function, though the exact action in relation to behaviour control have yet to be properly established. Evidence suggests that during learning, basal ganglia and medial temporal lobe memory systems are activated simultaneously and that in some learning situations competitive interference exists between these two systems. One theory suggests the basal ganglia decides which out of a number of possible actions the
may be planning, actually gets executed. Fitting this with idea that dopamine is used as a reward system for learning.
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