There are around 640 skeletal muscles within the typical human body. Almost every muscle constitutes one part of a pair of identical bilateral muscles, found on both sides, resulting in approximately 320 pairs of muscles. Nevertheless, the exact number is difficult to define because different sources group muscles differently, e.g. regarding what is defined as different parts of a single muscle or as several muscles.
The muscles of the human body can be categorized into several groups which include muscles relating to the head and neck, muscles of the torso or trunk, muscles of the upper limbs, and muscles of the lower limbs.