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.
Description. The concept of gender constancy, influenced by the cognitive development theory of French psychologist Jean Piaget (1896â1980), was introduced by Lawrence Kohlberg (1927â1987). In 1966, Kohlberg presented a revolutionary new view of early gender role development.