rhinencephalon

A largely archaic collective 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 despite the fact that 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. SEE ALSO: limbic system. SYN: smell-brain. [rhin- + G. enkephalos, brain]

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rhin·en·ceph·a·lon .rī-(.)nen-'sef-ə-.län, -lən n, pl -la -lə the anterior inferior part of the forebrain that is chiefly concerned with olfaction and that is considered to include the olfactory bulb together with the forebrain olfactory structures receiving fibers directly from it and often esp. formerly the limbic system which is now known to be concerned with emotional states and affect called also smell brain

rhin·en·ce·phal·ic .rī-.nen-sə-'fal-ik adj

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n.

the parts of the brain, collectively, that in early stages of evolution were concerned mainly with the sense of smell. The rhinencephalon includes the olfactory nerve, olfactory tract, and the regions now usually classified as belonging to the limbic system.

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rhi·nen·ceph·a·lon (ri″nən-sefґə-lon) [rhin- + encephalon] 1. a term generally applied to certain parts of the brain previously thought to be concerned entirely with olfactory mechanisms, including the olfactory nerves, bulbs, tracts, and subsequent connections (all olfactory in function) and the limbic system (not primarily olfactory in function); it is homologous with the olfactory portions of the brain in certain other animals. Called also olfactory brain and smell brain. 2. a term formerly used in official terminology to designate the area of the brain comprising the substantia perforata anterior, stria diagonalis (Broca), area subcallosa, and gyrus paraterminalis. 3. one of the portions of the telencephalon in the embryo.