The Probert Encyclopaedia of Heraldry

ESCUTCHEON

In heraldry, the escutcheon is the surface, usually a shield, upon which bearings are marshalled and displayed. The surface of the escutcheon is called the field, the upper part is called the chief, and the lower part the base That side of the escutcheon which is on the right hand of the knight who bears the shield on his arm is called dexter, and the other side sinister.
Research Escutcheon