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).
Gender and Gender Identity at a Glance. 1  Gender is our social and legal status as girls and boys, women and men. 2  Gender identity is how you feel about and express your gender.  Culture determines gender roles and what is masculine and feminine.