Complex sentence: The Mylohyoid muscle, flat and triangular, is situated immediately above the anterior belly of the digastric muscle, and forms, with its fellow of the opposite side, a muscular floor for the cavity of the mouth.
Split into simpler sentences: The mylohyoid muscle is flat and triangular, and is situated immediately above the anterior belly of the digastric muscle. It forms, with its fellow of the opposite side, a muscular floor for the cavity of the mouth.