What is the glossopharyngeal nerve?

What it is

• The glossopharyngeal nerve contains both motor and sensory fibers, and is distributed, as its name implies, to the tongue and pharynx. It is the nerve of ordinary sensation to the mucous membrane of the pharynx, fauces, and palatine tonsil, and the nerve of taste to the posterior part of the tongue. It is attached by three or four filaments to the upper part of the medulla oblongata, in the groove between the olive and the inferior peduncle.
• The sensory fibers arise from the cells of the superior and petrous ganglia, which are situated on the trunk of the nerve, and will be presently described. When traced into the medulla, some of the sensory fibers, probably sympathetic afferent, end by arborizing around the cells of the upper part of a nucleus which lies beneath the ala cinerea in the lower part of the rhomboid fossa.
• Many of the fibers, probably the taste fibers, contribute to form a strand, named the fasciculus solitarius, which descends in the medulla oblongata. Associated with this strand are numerous nerve cells, and around these the fibers of the fasciculus end. The somatic sensory fibers, few in number, are said to join the spinal tract of the trigeminal nerve.
• The somatic motor fibers spring from the cells of the nucleus ambiguus, which lies some distance from the surface of the rhomboid fossa in the lateral part of the medulla and is continuous below with the anterior gray column of the medulla spinalis. From this nucleus the fibers are first directed backward, and then they bend forward and lateralward to join the fibers of the sensory root.
• The nucleus ambiguus gives origin to the motor branches of the glossopharyngeal and vagus nerves, and to the cranial part of the accessory nerve.