A superior nerve simply refers to a nerve anatomically located on top, or at a higher place. Given that many higher order organisms, including humans, have both bilateral and vertical design, many anatomical structures often come either in left and right pairs or upper and lower parts. The term is therefore normally used to identify and distinguish a nerve from its comparative inferior nerve located below or beneath it. The nerves themselves can have different functions, but the superior-inferior distinction is one of orientation defined by the axis of gravity, also called the transverse plane.
Nerves are bundled fibers of elongated neural cells capable of chemically transmitting an electrical signal to each other. Whether their primary functions are sensory or motor, major nerve fibers typically connect to and merge with the central nervous system’s spinal cord or directly with the brain. Some will branch into a superior nerve and inferior nerve, as well as laterally into left and right nerves. Many will fractally branch into increasingly finer nerves to reach nearly the entirety of a body’s organs and tissues. Although some major nerves are bimodal, many are additionally defined by the directionality of their electric signal — afferent nerves carry signals toward the central nervous system, and efferent nerves carry them away.
The vagus nerve, which splits into a right and left pair, is among the most important of the major nerves. About 80-90 percent of the thick bundles are afferent nerves originating from the body’s internal organs, transmitting information on their status directly to the brainstem for it to accordingly adjust the body’s involuntary autonomic functions. More than a dozen major nerves branch from the vagus nerves. One of the first to do so is the superior nerve of the laryngeal, which controls the muscles of the larynx that stretch the vocal cords. Its inferior counterpart, called the recurrent laryngeal nerve, controls all the other muscles of the larynx; and together, they make human speech possible.
Another major nerve distinctively important for humans is the gluteal, which also is paired vertically. They, too, are efferent motor nerves. The inferior gluteal nerve transmits muscle signals to the gluteus maximus, commonly called the buttocks. The superior nerve of the gluteal does the same with the gluteus medius, the minimus and other smaller muscles of the buttocks and hips. The two gluteal nerves, by coordinating the muscles they respectively control, enable humans to stand and walk upright.