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.
sex-influenced inheritance. Inherited traits for which the genes are on autosomes, but their expression is influenced by the sex chromosomes (e.g., the reproductive organs). See also: inheritance. sex-inÂ·fluÂ·enced inÂ·herÂ·iÂ·tance.