The upper part of the trapezius muscle is the primary target of the shoulder shrug. The trapezius is a triangular muscle that makes up the upper back, running from the back of the neck and down along the spine, lying over the shoulder blades.
In general terms, sex refers to the biological differences between males and females, such as the genitalia and genetic differences. Gender is more difficult to define but can refer to the role of a male or female in society (gender role), or an individual's concept of themselves (gender identity).
Sexual orientation and gender identity are radically different from race and thus should not be elevated to a protected class in the way that race is. First, race manifests itself readily, whereas sexual orientation and gender identity are ambiguous, subjective, and variable traits. Second, sexual orientation and gender identity are linked to actions, which are a proper subject matter for moral evaluation. Race is not.