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.
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.