A wearable motion monitoring device including: a housing sized and shaped to be positioned between a body region of a subject and a garment worn by the patient； a marker included in said housing, said marker including at least one light emitter, wherein said light emitter is positioned to emit light from an upper surface of said marker, such that said at least one light emitter is indicative of displacements of said body region； at least one garment holder incorporated in said housing, said holder serves as an anchoring point between said marker and said garment, said garment overlies said marker when anchored by said at least one garment holder.
