1.NounA small muscle of the middle ear that is located in the bony canal just above the bony part of the Eustachian tube, that arises from the canal containing it, from the cartilaginous portion of the Eustachian tube, and from the adjacent greater wing of the sphenoid bone, that is inserted by a long tendon into the manubrium of the malleus near its base, and that serves to adjust the tension of the tympanic membrane.