A largely archaic, and now rarely used, term denoting the parts of the cerebral hemisphere directly related to the sense of smell: the olfactory bulb, olfactory peduncle (together still listed as the first cranial nerve or olfactory nerve even though they form part of the central nervous system), olfactory tubercle, and olfactory or piriform cortex including the cortical nucleus of the amygdala. The term originally also encompassed the hippocampus, the entire amygdala, and the fornicate gyrus, all of which are no longer believed to be specifically related to the sense of smell.
[rhin- + G. enkephalos, brain]
See Also: limbic system
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Examples: glitazone, GI cocktail, etc.