Extracolumella

The extracolumella, sometimes called the extrastapes or hyostapes, is an anatomical structure, generally cartilaginous, found in the middle ear of some tetrapods, which connects the columella to the tympanic membrane, or eardrum. It acts as the intermediary between the eardrum and the columella, between which it transfers sound in the form of vibrations. Once mistakenly thought to have played a role in the evolution of the mammalian ear, it is now believed to be a separate structure from the mammalian ossicles. It is, however, believed to be homologous to the mammalian .