Human Anatomy Part 2 - K. A. Dyubenko A. K. Kolomiyytsev Yu. B. Chaykovsky 2008

Special Part
Sense organs, organa sensuum
Vestibulocochlear organ - Pathway of the statokinetic analyzer

The Cell bodies of the first (bipolar) Neurons of the statokinetic analyzer are located in the vestibular ganglion (ganglion vestibulare), situated at the Cytology/practical/108.html">Fundus of the internal acoustic meatus. The vestibular ganglion consists of two parts: the superior part (pars superior) and the inferior part (pars inferior). The peripheral processes of the Cells in the superior part form the utricular nerve (nervus utriculans) and the anterior and lateral ampullary nerves (nervi ampullares anterior et lateralis), which pass through the openings of the superior cribriform macula to reach the receptor Cells of the macula of the utricle, as well as the anterior and lateral ampullae. The saccular nerve (nervus saccularis) and the posterior ampullary nerve (nervus ampullaris posterior) arise from the inferior part and pass through the openings of the middle and inferior cribriform maculae to the receptor cells of the macula of the saccule and the posterior ampulla, respectively. The epithelium of the maculae responds to linear acceleration and deviations from the vertical, whereas the epithelium of the ampullary crests responds to angular acceleration in any of the three planes in which the semicircular canals are located.

The central processes of the vestibular ganglion cells form the vestibular component of the cranial nerve VIII, which enters the Brainstem at the cerebellopontine angle. Before reaching the floor of the Fourth ventricle, the fibers of the vestibular division divide into ascending and descending branches. The ascending fibers terminate in the superior vestibular Nucleus.

It has been established that some of these fibers, after passing through the aforementioned nucleus, continue to the cerebellar fastigial nucleus (nucl. fastigii), where they terminate. Consequently, the fastigial nucleus can be considered the fifth vestibular nucleus.

The descending fibers terminate in the inferior, lateral, and medial vestibular nuclei.

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Fig. 229. Diagram of the Auditory pathway

Fig. 230. Diagram of the statokinetic pathway

The processes of the third-order neurons originate in the thalamus (optic thalami) and project to the cortex of the middle temporal gyrus. However, unlike the Auditory Analyzer, the statokinetic analyzer lacks a strictly localized cortical representation. The processes of its third-order neurons also terminate in the frontal and parietal lobes.

The statokinetic analyzer plays a primary role in the perception of HEAD position, body posture, and direction of movement. Nevertheless, changes in BODY POSITION AND movement are also perceived by other Sensory systems: the visual, exteroceptive, and proprioceptive analyzers. Impulses arising from The stimulation of all these receptors are directed to the Cerebral Cortex, where their integration takes place.