The platysma is a superficial muscle that overlaps the sternocleidomastoid. It is a broad sheet arising from the fascia covering the upper parts of the pectoralis major and deltoid; its fibers cross the clavicle, and proceed obliquely upward and medially along the side of the neck.
For example genetic differences, females inherit X chromosomes from their father giving them a genetic make-up of XX, while males inherit a Y chromosome from their father, thus giving them a genetic make-up of XY.
Children are exposed to many factors which influence their attitudes and behaviours regarding gender roles. These attitudes and behaviours are generally learned in the home and are then reinforced by the child's peers, school experience and the media. The strongest influence on gender role development seems to occur within the family, with parents passing on, both overtly and covertly, their own beliefs about gender (Witt, 1997).