Anatomy of the Vessels and Nerves of the Head and Neck (Angioneurotomy) - Chornokulskyi S.T. 2009

Nerves of the Head and Neck
Olfactory nerve

[I] (n. olfactorius) Fig. 30.

This is a collection of axons from the neurosensory epithelial Cells of the mucosa in the regio olfactoria, forming 15–30 olfactory filaments that pass through the cribriform plate of the Ethmoid bone to reach the olfactory bulb (see "Olfactory Organ").

Olfactory organ (organum olfactorium)

Through its receptors (olfactory neurosensory epithelial cells — epitheliocytus neurosensorius olfactorius) located in the olfactory region of the nasal mucosa, it initiates the Pathways of the analyzer (1st neuron).

There are about 30 million receptor Neurons, whose axons form 15–30 olfactory filaments (fila olfactoria) that penetrate through the cribriform plate to reach the olfactory bulb. The latter contains The Cell bodies of the second-order neurons (mitral cells), whose axons form the olfactory tract (tractus olfactorius).

Some of the axons of the second-order neurons reach the neurons of the olfactory trigone, the anterior perforated substance, and the septum pellucidum, while a second, larger group of axons divides into three olfactory striae (striae olfactoriae): lateral, intermediate, and medial.

The lateral olfactory stria (stria olfactoria lateralis), after synapsing on the third-order neurons of the olfactory trigone, reaches the cortex of the uncus, branching in part to the subcortical olfactory center—the amygdaloid body.

The intermediate olfactory stria (stria olfactoria intermedia) synapses on the third-order neurons of the anterior perforated substance and continues through the lamina of the septum pellucidum, the fornix, and the fimbria hippocampi to the cortex of the uncus.

The medial olfactory stria (stria olfactoria medialis), after synapsing on the third-order neurons of the subcallosal area, curves around the corpus callosum and runs within the fasciolar and dentate gyri (gyri fasciolaris et dentatus), reaching the cortex of the uncus.

A small portion of the axons of the second-order neurons, as well as third-order neurons (particularly from the olfactory trigone), from both the ipsilateral and contralateral sides, reach the neurons of the subcortical olfactory center—the mammillary body. The axons of the mammillary body neurons reach the anterior thalamic nuclei as part of the mamillothalamic tract (Vicq d'Azyr's bundle), and also pass via the fimbria hippocampi to the cortex of the uncus on their own side, and through the hippocampal commissure to the fornix of the opposite side.

The cortex of the uncus serves as the cortical center (Nucleus) of the olfactory analyzer. It should be emphasized that all Sensory Organs in a unified Organism are interconnected, especially within the Cerebral Cortex, where the centers of all analyzers possess extensive associative contacts. This accounts not only for their interconnection, but also for mutual influence and functional compensation among the various organs.

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Fig. 30. Pathway of the olfactory analyzer (by neurons)

1 - Olfactory neurosensory epithelial cell (epitheliocytus neurosensorius olfactorius)

1st neuron;

2 - dendrites extending to the mucosa of the regio olfactoria;

3 - axons of the 1st-order neurons forming the nervi olfactorii;

4 - cribriform plate (lamina cribrosa);

5 - olfactory bulb (bulbus olfactorius), 2nd-order neuron;

6 - olfactory tract (tractus olfactorius);

7 - olfactory trigone (trigonum olfactorium);

8 - lateral olfactory stria (stria olfactoria lateralis);

9 - uncus;

10 - amygdaloid body (corpus amygdaloideum);

11 - intermediate olfactory stria (stria olfactoria intermedia);

12 - lamina of septum pellucidum (lamina septi pellucidi);

13 - fornix (fornix);

14 - fimbria of hippocampus (fimbria hippocampi);

15 - medial olfactory stria (stria olfactoria medialis);

16 - corpus callosum (corpus callosum):

17 - fasciolar gyrus (gyrus fasciolaris);

18 - dentate gyrus (gyrus dentatus)