Olfactory brain

The olfactory brain or rhinencephalon is a functionally defined term used to summarize various parts of the endbrain ( telencephalon ) that are used for olfactory perception . The olfactory brain in a narrow sense includes the two olfactory bulbs as primary olfactory areas, their projections and the secondary olfactory areas reached by them. The secondary olfactory areas are located in the basal cortical areas of the endbrain; they show an allocortical structure, are mainly assigned to the palaeocortex and are also referred to as the olfactory cortex .

The olfactory brain includes parts that lie in the human endbrain at the base of the hemispheres : The olfactory bulb (2) and the olfactory tract (3) are visible to the side of the rectal gyrus (1) . This widens to the trigonum olfactorium (4) - where the nucleus olfactorius anterior lies - and branches into medial and lateral striae olfactoriae , which hold the substantia perforata [anterior] (5) between them. Adjacent is the cortex prepiriformis (not marked, near the 7). From the parahippocampal gyrus (7) alone the anterior section is counted as the rhinencephalon.

The rhinencephalon represents ancestral parts of the endbrain. In contrast to non- primates , it is rather poorly developed in humans at the base of the endbrain hemispheres .

In detail, the olfactory brain includes:

• the olfactory bulb (olfactory bulb) as the primary olfactory area ; multi-layer structure,
  • The axons of primary sensory cells of the olfactory epithelium terminate in the layer of the glomeruli
  • The cell bodies of secondary afferent projection neurons lie in the layer of the mitral cells
• Portions of the central olfactory tract
  • the olfactory tract in the olfactory stalk
  • widening to the trigonum olfactorium
  • branching into the medial olfactory stria
  • and the stria olfactoria lateralis
• Switching station to the opposite side
  • the nucleus olfactorius anterior connects via the commissura rostralis
• as secondary olfactory areas of the olfactory cortex
  • the substantia perforata anterior (or the tuberculum olfactorium )
  • the cortex prepiriformis (paleocortical parts of the gyri ambiens and semilunaris in the lobe piriformis ) on the medial side of the temporal lobe
  • the pars corticomedialis ( nucleus corticalis ) of the amygdala ( corpus amygdaloideum , almond kernel)
  • only the foremost section of the entorhinal cortex in the parahippocampal gyrus

Individual evidence

1. ↑ Rhinencephalon in the Lexicon of Neuroscience on Spektrum.de, accessed on July 22, 2019.

literature

• K. Akert: Organ of smell and central olfactory pathways. In: Alfred Benninghoff (term): Macroscopic and microscopic human anatomy . Urban & Schwarzenberg, Munich 1985, Volume 3: Nervous system, skin and sensory organs. ISBN 3-541-00264-6 , chapter 25.