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.
One of the main differences regards gender identification. Gender, according to many experts, is a social rather than biological definition. The social structures regarding male and female roles are what define gender, rather than the anatomical and scientific definitions that define what sex a person is.