Corpus: Olfactory bulb

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AI translation

This text has been translated by an AI and may sound raw. It will be reviewed shortly. Thank you for your patience!

from Latin: bulbus - onion; olfacere - to smell, sense, scent
Synonym: olfactory bulb
English:

1. Definition[Bearbeiten]

The olfactory bulb is a protruding part of the brain that lies directly below the frontal brain and is used for odour perception.

Note: Due to its elongated shape, the olfactory bulb has long been misinterpreted as the olfactory "nerve".

2. Anatomy[Bearbeiten]

The olfactory bulb is part of the olfactory brain (rhinencephalon) and is located on the lamina cribrosa of the ethmoid bone. The olfactory nerves (fila olfactoria) run through the fine bone canals of the lamina cribrosa from the nasal cavity to the dendrites of mitral cells and tufted cells in the olfactory bulb. This can be subdivided into 2 parts:

  • olfactory bulb ("main olfactory bulb")
  • Bulbus olfactorius accessorius ("secondary olfactory bulb")

3. Histology[Bearbeiten]

Histogenetically, the olfactory bulb is an outgrowth of the cerebral cortex. However, the region no longer has a cortical character, as its cell count is significantly smaller than that of the rest of the cerebral cortex. In its structure there are 6 layers from the outside inwards:

  • Nerve layer
  • Glomerular layer (glomerular layer)
  • External plexiform layer (EPL)
  • Mitral cell layer
  • Internal plexiform layer (IPL)
  • Granular cell layer (granule cell layer)

The nerve cells form dense spheroid or ellipsoidal nerve plexuses in the olfactory bulb, which are known as glomeruli olfactorii. In their neighbourhood are inhibitory interneurons, which include the periglomerular cells and the granule cells.

4. Function[Bearbeiten]

The olfactory bulb serves to process the incoming stimuli from the olfactory mucosa and their connection to projection neurones. However, it is not a simple filter station, as it is influenced by incoming "top-down" information from higher brain centres, e.g. from the amygdala, the neocortex, the hippocampus, the locus coeruleus and the substantia nigra. The olfactory bulb probably fulfils the following functions:

  • Amplification of odour perception
  • Differentiation of odour information
  • Filtering out secondary odours
  • Modification of odour perception by higher brain centres

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