Wrisberg's Nerve

WRISBERG'S NERVE, s. nervus intermedius, belongs to the cranial nerves (it is considered the XIII); according to its structure and function, it is controversial, but most likely this nerve is mixed. Its motor root originates in the pons Varolii, in the nucleus salivatorius superior, lying dorso-medially from the nucleus of the facial nerve; upon exiting the pons Varolii, it is situated between the VII and VIII nerves, and then enters the internal acoustic meatus together with the VII nerve, from which it separates at the level of the geniculate ganglion and passes into the chorda tympani and the lingual nerve; its fibers terminate in the submaxillary ganglion, from which fibers then proceed for the innervation of the submaxillary gland. The sensory fibers of Wrisberg's nerve arise from the central processes of the cells of the geniculate ganglion, which lies in the geniculum of the facial nerve; the peripheral processes of the ganglion cells are directed toward the chorda tympani and the lingual nerve, where they run together with the motor branch, and then terminate in the tongue and serve as a conductor of taste sensations from the anterior 2/3 of the tongue. The central processes of the ganglion cells, or the sensory root, upon exiting the geniculate ganglion, join with the motor root and are directed toward the pons Varolii; in the pons Varolii, it enters the composition of the tractus solitarius, in which it assumes a descending direction and gradually terminates in the nucleus of the tractus solitarius, which is the primary center of taste; from it begins the second neuron, common with the glossopharyngeal nerve, the fibers of which cross to the other side, decussating in the raphe, assume an ascending direction, and are situated in the substantia reticularis alba, gradually approaching the medial lemniscus; together with it, they terminate in the ventral nucleus of the optic thalamus, from where the third neuron begins, proceeding to the cerebral cortex (for details on the conducting pathways and the center of taste, see Taste). The anatomical structure of the nerve indicates its mixed function: one part of the nerve, running in a centrifugal direction, is secretory, terminates in the salivary gland, and belongs to the parasympathetic system; the other part, running in a centripetal direction, is sensory, carrying taste sensitivity from the anterior 2/3 of the tongue. Involvement of this nerve in a pathological process leads to disorders of taste and salivation in the corresponding regions.

E. Kononov.