Inferior Salivary Nucleus: Structure, Function & Diseases

The IX cranial nerve receives its fibers from the inferior salivary nucleus, among others. They continue to the parotid gland and supply it. The parotid gland is an important organ for the production of saliva.

What is the inferior salivary nucleus?

The inferior salivatory nucleus is a cranial nerve nucleus. It is located in the medulla oblangata. As part of the central nervous system, it contributes to the supply of some areas in the mouth and pharynx. Its axons draw with the IX cranial nerve. This is the glossopharyngeal nerve. With its branches, the cranial nerve innervates areas in the head that are important for taste recognition, the swallowing process, and the regulation of breathing. Through the cells of the inferior nucleus salivatorius, the cranial nerve receives efferent fibers. With these, it moves on and eventually supplies the parotid gland. On its way to the parotid gland, the first neurons are recorded in the nucleus salivatorius inferior. Further recording of neurons occurs in the otic ganglion. The parotid gland, weighing 20-30 g, is the largest gland in the human body that produces saliva. This is important in the decomposition of food in the mouth and also in the formation of speech. In addition, saliva provides adequate nourishment to the mucous membranes in the mouth and throat.

Anatomy and structure

The IX cranial nerve derives its fibers from four different nuclei. The glossopharyngeal nerve is fed by the nucleus ambiguus, the nucleus salivatorius inferior, the neuclei tractus solitarii, and the nucleus spinali nervi trigemini. The cells of the nucleus ambiguus innervate the muscles of the pharynx and soft palate. The neuclei tractus solitarii, together with the nucleus spinalis nervi trigemini, innervate the posterior third of the tongue. Some cells also supply the auditory tube and the middle ear. The inferior salivatory nucleus, together with the superior salivatory nucleus, belongs to the parasympathetic nuclei of the brainstem. Its fibers have a complex course. They innervate the parotid gland, the parotid gland. This is one of the largest salivary glands in the human body. It is located on either side of the human head just below the earlobe. The secretion of the parotid gland leads to the supply of saliva to the mouth. It also produces the saliva necessary for the mucous membranes in the throat, oral cavity and lips. Saliva contains important electrolytes, proteins and enzymes.

Function and tasks

The function of the inferior salivary nucleus is to provide neurons. From these, the glossopharyngeal nerve draws its fibers. With them, it innervates important areas of the face. Among other things, the cranial nerve is responsible for supplying the parotid gland. In order to be able to do this to a comprehensive extent, it receives parasympathetic fibers from the inferior salivary nucleus. These fibers continue to the otic ganglion, the so-called ear node. There they undergo further switching until they then reach the parotid gland. Thus, the nucleus salivatorius inferior plays a significant role in enabling subsequent saliva formation in the parotid gland. Saliva has multiple functions. It plays just as important a role in speech formation as it does in supplying the mucous membranes in the mouth and throat. It protects and repairs them. In addition, it is needed for food intake. Saliva in the mouth breaks down carbohydrates and thus performs a predigestive function. Saliva keeps the oral flora in balance and prevents the formation of plaque on the teeth and in the interdental spaces. The existing tooth substance is remineralized by the saliva. In addition, saliva has an important function in the defense reaction in the mouth and throat against various bacteria and viruses. The act of swallowing requires saliva from the parotid gland in addition to various muscles and nerves for a smooth process.

Diseases

Lesions of the various so-called glossopharyngeal nuclei usually lead to impairment of the corresponding functions. A total failure is to be classified as rather unlikely, since a central failure occurs only in exceptional cases. In most cases, a change in sensitivity or partial impairment is to be expected. Lesions of the nucleus salivatorius inferior result in the IX.cranial nerve cannot form fibers from it at all or can no longer do so to a sufficient degree. This means that it must continue on its way when supplying the parotid gland with fewer fibers. As a result, a reduced salivary flow is to be expected. Dry mouth sets in and this leads to impaired speech formation as well as food intake. In addition, taste perception is often impaired. The papillae on the tongue are less sensitive to taste and therefore transmit their signals in a reduced form. Reduced salivary flow leads to bad breath, increased inflammation of the oral mucous membranes and a greater incidence of tooth decay. Food residues can only be removed in a reduced form due to a reduced salivary flow. The acids absorbed through food are no longer sufficiently neutralized and carbohydrates are no longer predigested. This slows down the overall digestive process. Increased dental hygiene is one way to compensate, but can be considered insufficient in establishing a balanced oral flora. The most common diseases of the parotid gland include viral and bacterial inflammation, salivary gland swelling, mumps, and tumor formation.