The North American Industry Classification System (NAICS) is a numerical system that classifies business establishments by industry. This system is used by Federal statistical agencies for the purpose of collecting, analyzing, and publishing statistical data related to the U.S. business economy.nd although the NAICS code system is used more often today, the SIC system is still being used by some government bodies, including the Securities and Exchange Commission. NAICS industries are identified by a 6-digit code, in contrast to the 4-digit SIC code.
Trapezius Muscle. The trapezius is one of the major muscles of the back and is responsible for moving, rotating, and stabilizing the scapula (shoulder blade) and extending the head at the neck. It is a wide, flat, superficial muscle that covers most of the upper back and the posterior of the neck.
It covers the majority of the temporal bone and lesser portions of the frontal and parietal bones. The upper margin of the muscle follows the superior temporal line. Insertion: The temporal muscle inserts on the coronoid process of the mandible.Action: The temporal muscle acts in unison with the masseter and internal pterygoid muscles to close the jaws. Very importantly, it also helps to retrude or pull back the mandible.he depressors of the mandible act to open the lower jaw widely, a function which the muscles of mastication cannot perform. MUSCLES OF MASTICATION There are four paired muscles of mastication. They are the masseters, the temporals, the internal pterygoids, and the external pterygoids.